Renewable Energy Guide for Highway Maintenance Facilities (2013)

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P A R T I V Case Studies

139 20.1 Background Part IV of the Renewable Energy Guide for Highway Maintenance Facilities integrates a case studies document that was originally a stand-alone document developed under NCHRP Project 20-85. The 11 case studies provide examples of the application of various renewable energy technologies and design strategies to maintenance facilities. The lessons learned and best practices from the case studies should prove valuable to transportation facility planners, designers, and decision makers. 20.2 Approach Candidate projects for case studies were based primarily on two sources that were developed during the preparatory phase of NCHRP Project 20-85: • Literature review summary. This summary provided information on renewable energy tech- nology developments, including projects demonstrating the application of the technologies on various buildings. • Survey of renewable energy technologies at highway maintenance facilities. Under this task, information was obtained on the status of and plans for the use of renewable energy technologies and strategies on highway maintenance facilities. Included was information on specific projects and/or contacts for potential case studies. A total of 35 projects were identified, of which 15 were considered as the most promising for case studies. Key factors in determining the mix of projects to include as case studies were: • Renewable energy technology type and end use, • Building type and application, • Climate region, • Lessons learned, and • Data availability. Ultimately, 11 projects were selected as case studies, which included various types of vehicle- related maintenance facilities—road maintenance, transit, and public works: 1. St. Clair, MO, Maintenance Facility Solar Thermal Systems. 2. Fort Drum, NY, Solar Ventilation Air Heating System on Maintenance Facilities. 3. Plattsburgh, NY, Solar Ventilation Air Heating System on Airport Facilities. 4. Coney Island, NY, Train Maintenance Facility Solar Water Heating System. 5. Denver, CO, Public Works Central Platte Campus. 6. South Bend, IN, Public Transportation Organization Maintenance Facility. C H A P T E R 2 0 Introduction

140 Renewable Energy Guide for Highway Maintenance Facilities 7. Caltrans Clean Renewable Energy Bonds Program, Sunrise Maintenance Station Photovoltaic System. 8. Milford, UT, Highway Maintenance Station Wind Turbine. 9. Ohio Department of Transportation Northwood Outpost Garage Wind Turbine. 10. Elm Creek Park Maintenance Facility (MN), Geothermal Heat Pump System. 11. Kilauea Military Camp, HI, Corrosion-Resistant Roof with Integrated Photovoltaic System. For each case study, information was gathered via interviews with the project principals and a review of the various documents obtained from the contacts interviewed or online sources, including plans/specifications and project reports. We used a data-collection form that mirrored the outline for the case studies. This allowed us to organize the information by the major steps in project development process and outcomes: • Pre-design (project planning) phase. • Design phase. • Construction phase. • Results (post-commissioning project operation phase). • Lessons learned. • Future plans.

141 21.1 Overview of the Case Studies The 11 case studies cover a variety of technologies, building applications, geographic loca- tions, project delivery, and funding mechanisms (see Table 21-1): • Renewable energy technologies. The technologies include solar photovoltaics (four projects), solar thermal for space heating (one project), ventilation air heating (two projects), water heating (two projects), wind energy (two projects), and geothermal (ground source) heat pumps (two projects), as well as design strategies to make better use of site resources to meet the building’s energy requirements (e.g., daylighting—two projects). • New versus existing buildings. Four of the projects are new buildings, while the others are existing facilities that have had renewable energy technologies added. • Locations. The geographical coverage includes nine states—California, Colorado, Indiana, Minnesota, Missouri, New York, Ohio, Utah, and Hawaii—representing seven ASHRAE cli- mate zones (1A, 3B, 4A, 5A, 5B, 6, and 7). • Project delivery mechanisms. Four of the projects are design–build, while the rest are design– bid–build. The designs were developed in-house for three of the projects, while the designs of the other projects were contracted out. • Project funding mechanisms. Four projects required no direct capital funds from the agency or organization. Alternative financing mechanisms included PPAs, utility financing, and bonds. Six of the projects used financial incentives from utilities or federal or state agencies to reduce project capital costs. Table 21-2 briefly characterizes each of the 11 case studies in terms of the renewable energy technologies, performance and economics, and lessons learned/best practices. Some of the key findings regarding renewable energy technology are highlighted in the following: Solar Space Heating. The roof-mounted solar air heating system at the St. Clair, MO, mainte- nance facility appears to be operating well; however, there is uncertainty about savings due to lack of performance monitoring equipment. The sense is that energy is being saved, but due to the relatively high location of the solar-heated air distribution point (near the ceiling), it is not clear whether building occupants are aware of the heat from the solar air collectors. Due to the relatively high costs of the system, it has a long payback period. Solar Ventilation Air Heating. The solar ventilation air heating systems manufactured by Solar- Wall appear to be performing well, based on projections of short-term monitoring results. The Fort Drum, NY, system is an earlier design that has no glazing over the perforated corrugated metal collector wall. The system at Plattsburgh International Airport, NY, has the upper portion glazed to provide higher outlet temperatures. This newer system is providing higher tempera- tures, but as implemented, is not able to make the best use of the available heat. Nonetheless, C H A P T E R 2 1 Summary of Case Studies

142 Renewable Energy Guide for Highway Maintenance Facilities the monitoring indicates significant energy savings, even without the benefits of destratifica- tion (reduction of temperature gradients from floor to ceiling due to better mixing of air in the space). The relatively low capital cost of the system as compared to other solar thermal systems makes this a potentially attractive option where there are substantial ventilation air require- ments. In the case of Plattsburgh, the capital costs were fully covered by incentives. Solar Water Heating. The solar water heating systems at the St. Clair facility, while not moni- tored, appear to be providing substantial amounts of solar-heated water. During the summer months, the electric heating element is not required, indicating that the system is able to meet the entire requirements. The two separate systems serve domestic water purposes and vehicle washing, respectively. The flat plate liquid collectors/drain-back design is well suited for smaller Table 21-1. Renewable technologies, funding, and delivery mechanisms. Project Name and Location ASHRAE Zone Renewable Technology Funding Mechanism Delivery Mechanism St. Clair, MO• • • • • • • • • • • , Maintenance Facility Solar Thermal Systems 4A SH, SWH Direct DBB (agency design) Fort Drum, NY, Solar Ventilation Air Heating 6A SVH Direct DB Plattsburgh, NY, Solar Ventilation Air Heating 6A SVH ARRA grant DB Coney Island, NY, Train Maintenance Facility 4A SWH Utility financing and incentives DBB (NYPA design) Denver, CO, Public Works Central Platte Campus 5B PV, DL PPA, various incentives DB South Bend, IN, Public Transportation Organization (TRANSPO) Maintenance Facility 5A PV, GHP, DL Direct and ARRA grants FTA grants DBB Caltrans CREBs Program, Sunrise Maintenance Station 3B PV CREBs (bonds) and utility incentives DBB (agency design) Milford, UT, Highway Maintenance Station Wind Turbine 5B W Direct and state/fed grant DB (agency design) Ohio Department of Transportation Northwood Outpost Garage Wind Turbine 5A W Direct DBB Elm Creek Park Maintenance Facility (MN), Geothermal Heat Pump System 6 GHP Direct DBB Kilauea Military Camp, HI, Maintenance 1A PV Direct DBB Key: SWH (solar water heating), SH (solar heating), SVH (solar ventilation heating), PV (solar photovoltaics), W (wind turbine generator), GHP (geothermal heat pump), DL (Daylighting), ARRA (American Recovery and Reinvestment Act), FTA (Federal Transit Administration), CREBs (Clean Renewable Energy Bonds), DBB (design–bid–build), DB (design–build), NYPA (New York Power Authority).

Summary of Case Studies 143 Project Name and Location Renewable Technology Performance and Economics Lessons Learned and Best Practices St. Clair, MO• • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • , Maintenance Facility Solar Thermal Systems 2273 North Service Rd. East St. Clair, MO 63077 ASHRAE Zone 4A Solar air collectors for heating vehicle maintenance area. Two solar water heating systems to serve domestic hot water and vehicle washing. Rooftop installation on new 9,000 ft2 maintenance building. Performance is estimated since systems are not monitored. Solar Space Heating: Cost: $138,000 for 1,040- ft2 solar air collector system ($133/ft2). Annual savings: 215 MMBtu gas/$1,505. Payback: 92 years. Solar Water Heating: Cost: $16,000 for 256-ft2 liquid collector systems (two) ($63/ft2). Annual Savings: 16,676 kWh (56.9 MMBtu) elec./$1,156. Payback: 13 years. Solar water heating works well. Maintain design flexibility. Ensure good communication among all members of the project team. Be aware of special code requirements for solar equipment (e.g., wind loads for solar collectors). Install solar system performance monitoring equipment. Placement of solar-heated air output important for occupant comfort. Fort Drum, NY, Solar Ventilation Air Heating Systems Fort Drum, NY 13602 ASHRAE Zone 6A Unglazed transpired solar air collector systems (SolarWall) for ventilation air heating. Solar collectors installed on the facades of 27 existing vehicle maintenance buildings. Performance is estimated. Cost: $3,400,000 for 110,000-ft2 solar air collector systems ($31/ft2). Annual savings: 44,317 MMBtu gas/$398,853. Payback: 8.5 years. Systems appear to be performing well. • • • • Fan noise may be an issue in some cases. Solutions: variable-speed drives to reduce speed, adding silencers, and adding duct insulation for ducted systems. Gravity dampers for outside air intake should be avoided to eliminate the downward flow of cold air. Connect the system to existing direct digital control systems if available. Plattsburgh, NY, Solar Ventilation Air Heating Systems Plattsburgh International Airport 137 Margaret St. Plattsburgh, NY 13642 Two-stage unglazed transpired solar air collector systems (SolarWall) for ventilation air heating. Solar collectors installed on the Cost: $614,219 for 17,800-ft2 solar air collector systems ($34.42/ft2) for four buildings. Annual savings: 521 MMBtu gas (hangar 3)/$6,252 (hangar). Incorporate wall fans and destratification fans to help mix/distribute solar- heated ventilation air. Incorporate control strategy based on solar supply temperature and desired space air facades of three Payback: 19 years. temperature. existing 28,000-ft2 ASHRAE Zone 6A• hangars and one 26,50-ft2 industrial building. • • Output temperatures exceed expectations. No savings from destratification. • • • • • • • • • Coney Island, NY, Train Maintenance Facility Solar Water Heating System Brooklyn, NY 11224 ASHRAE Zone 4A Evacuated-tube collector solar water heating system to serve vehicle (train) wash. • Rooftop installation on existing 300,00-ft2 maintenance building. Cost: $564,905 for 1,762- ft2 solar evacuated-tube collector systems ($320.62/ft2). Annual savings: 104,000 kWh (355 MMBtu) elec./$100,000. Payback: 5.6 years. Water can be used as a good heat transfer fluid with evacuated-tube solar collector systems in colder climates. Ensure that solar collectors are certified to meet wind load specifications. Table 21-2. Summary of case studies. (continued on next page)

144 Renewable Energy Guide for Highway Maintenance Facilities Table 21-2. (Continued). Project Name and Location Renewable Technology Performance and Economics Lessons Learned and Best Practices • • • • • • • • • • • • • • • • • • • • • • System is performing well and close to predicted performance. Ensure good communications of the specifications among the system designer, specifier, solar collector manufacturer, and installer. Denver, CO, Public Works Central Platte Campus 1271 West Bayaud Avenue, Denver, CO 80223 ASHRAE Zone 5B Photovoltaic system for electricity. Daylighting strategies to reduce electric lighting requirements. Rooftop PV installation on new LEED Gold 39,546- ft2 fleet maintenance building. Cost: N/A. 20-year PPA for the 102-kW PV system. Annual savings: 153,506 kWh (524 MMBtu) elec./$5,986. Payback: N/A. Savings is discount of $0.039/kWh for electricity provided by the PV system. System appears to be performing well and exceeded projected output over first 10 months of operation. Get all the key players involved early to ensure that everyone knows the objectives and vision of the project. Plan examiners will bump wind loads/snow loads for untested technology like PV. Roofer must do all the penetrations of roof membrane in order to maintain the warranty. PPA covers all system operations, which benefits an entity like the City of Denver, which has no expertise in the operation and maintenance of a solar PV system. South Bend, IN, Public Transportation Organization (TRANSPO) Maintenance Facility 1401 South Photovoltaics, geothermal (ground source) heat pump and radiant slab heat distribution, daylighting, and super insulated building shell. Photovoltaic System: Cost: $600,000 for 93.5- kW system ($6,417/kW). • Annual savings: 97,259 kWh (332 MMBtu) elec./$5,474. • Payback: 110 years. Having a general contractor or construction manager hired as a team member early in the process would have been extremely valuable. Close coordination and scheduling between the Lafayette Boulevard, Roof-integrated thin- Ground-Source Heat Pump: subcontractors is needed South Bend, IN • • • • • 46612 ASHRAE Zone 5A film PV on a new 167,000-ft2 combination maintenance/office facility – LEED Platinum rating. Cost: N • /A. Annual savings: 38,429 kWh (131 MMBtu) elec./$2,152. Payback: N/A. to avoid problems. Provide real-time performance monitoring for measurement and verification and education purposes. • • • • • • • • • • • Caltrans CREBs Program, Sunrise Maintenance Station Photovoltaic System 11325 Sanders Drive Rancho Cordova, CA 95742 ASHRAE Zone 3B Rooftop PV installation on existing 4,000-ft2 storage building. Cost: $193,402 for 35.6- kW system ($5,433/kW). Annual savings: 46,546 kWh (159 MMBtu) elec./$6,703. Payback: 23 years. System at Sunrise facility is performing as expected, except for some down time due to inverter problems. Make sure to work with the utility before undertaking PV projects. Plan for regulatory reviews early in the design process. Roof-mounted PV panels should be tilted at least 10 degrees to enable dirt to wash off. Specify slightly oversized inverters (about 5% larger) to ensure efficient, reliable operation. All costs of performance monitoring, including ongoing analysis, should be accounted for. •

Summary of Case Studies 145 Table 21-2. (Continued). Project Name and Location Renewable Technology Performance and Economics Lessons Learned and Best Practices • • • • • • • • • • • • • • • • • • • • • • Milford, UT, Highway Maintenance Station Wind Turbine Milford, UT 84751 ASHRAE Zone 5B Wind turbine generator to serve existing 3,434-ft2 maintenance station. Performance is derived from utility meter data, not from separate monitoring system. Cost: $13,500 for 1.8-kW system ($7,500/kW). Annual savings: 3,250 kWh (11 MMBtu) elec./$260. Payback: 52 years. Using maintenance crews to assist with installation is a cost-effective method to match project grants. Keep the key players involved throughout the process. Emphasize energy efficiency as part of the project. Include energy monitoring to encourage occupants to practice conservation. Ohio Department of Transportation, Northwood Outpost Garage Wind Turbine 200 Lemoyne Road, Northwood, OH 43619 ASHRAE Zone 5A Wind turbine generator to serve existing 57,182-ft2 maintenance complex. Cost: $200,000 for 32-kW system ($6,250/kW). Annual savings: N/A. Payback: 12 to 16 years. No performance data yet. Identify and verify any environmental restrictions at the proposed site prior to selecting a particular technology. Researching the companies/contractors involved in the manufacture of equipment and construction of renewable energy projects is critical. Make sure procurement process accounts for risks with new technology— timely repair and parts availability requirements. • Elm Creek• • • • • • • • • • • • • • •• • • • • • • • Park Maintenance Facility (MN), Geothermal Heat Pump System 12400 James Deane Parkway Maple Grove, MN 55369 ASHRAE Zone 6 Geothermal (ground source) heat pump systems that serve new 11,676-ft2 maintenance garage. Cost: N/A. Annual Savings: N/A. Payback: N/A. Do thorough research on equipment manufacturers. Perform soil conductivity tests before considering geothermal heating and cooling. Extreme care needs to be taken in installation of well field loops to prevent contamination. Require VFDs on pumps. Water-to-air units had fewer problems than water-to-water units. Kilauea Military Camp, HI, Corrosion-Resistant Roof with Integrated Photovoltaic System Kilauea Military Camp Volcanoes National Park, HI 96718 ASHRAE Zone 1A Roof-integrated thin- film photovoltaic system on existing 9,000-ft2 vehicle storage structure. Cost: $195,674 for 15-kW system ($5,433/kW). Annual savings: 19,128 kWh (65.3 MMBtu) elec./$6,729. Payback: 29 years. System electricity output is as expected. The permitting process is a critical-path item and more likely to be a cause of delay than technical or construction issues. If breaks occur in the material’s surface, the cells are extremely vulnerable to intra-cell corrosion. This vulnerability within the cells dictates that any breaks should be sealed at once.

146 Renewable Energy Guide for Highway Maintenance Facilities applications. Freeze protection is provided by draining of the water from the collectors when the collector loop pump shuts off. The evacuated-tube liquid collector-based water heating system at the Coney Island, NY, train washing facility has demonstrated performance close to projected during its first year of operation. While the system is considerably more expensive than the flat plate collector system on an installed cost basis, it is capable of providing better performance on cold sunny days, and delivering higher temperatures (if needed). Thus far, there have been no problems with this pressurized all-water system, in terms of any freezing or over-temperature issues. Freeze protection of the collectors is provided by recirculation of heated water when the outside air temperature falls below a specified set point. The economics look attractive in this particular application due to the avoidance of very high electric demand charges ($30 kW). Furthermore, the system is paid for over a 10-year period, structured in a way to ensure positive cash flow. In regions where electricity costs are more typically like the national average, the economics would not be nearly as attractive. Solar Photovoltaic Systems. The photovoltaic systems appear to be working well. The new Central Platte, CO, public works facility PV system exceeded its expected output for the first 10 months of operation. The crystalline silicon PV modules are architecturally integrated in the sawtooth design of this LEED Gold fleet maintenance/office facility and are generating electricity under a PPA. The agreement enables the system to be paid off through power purchases, structured in a way to elimi- nate up-front costs. The savings are assured since the agreed-upon rates are discounted relative to standard electricity rates over the term of the agreement. Performance data from the Sunrise Mainte- nance Facility’s crystalline silicon PV system in Rancho Cordova, CA, indicate that the system output is in line with expectations. There were some issues with the inverters that have been remedied. The CREBs program used to finance the system eliminated initial capital costs, making this an attractive proposition. The roof-integrated thin-film system at the new South Bend, IN, Transportation Orga- nization (TRANSPO) maintenance facility represents a different technology (lower efficiency), but is amenable to a variety of roof integration situations. Performance data from the system are not yet available. The PV system at Kilauea Military Camp (KMC) uses a similar technology. Wind Turbine Generators. The small wind turbine generator at the Milford, UT, maintenance facility appears to be performing well based on analysis of electricity bill data. System costs were able to be reduced from $13,500 to $6,500 due to grant funds that made the project economical. The Northwood, OH, wind turbine is not yet operational, so there is no performance data to report. The main problem was a damaged blade, which has taken many months to replace. The projected payback is 12 to 16 years. Geothermal Heat Pumps. The geothermal heat pumps at the South Bend, IN, TRANSPO facil- ity appear to be working well in terms of meeting heating needs. They are not separately metered, and the savings are based on projections. The Elm Creek Park geothermal system in Maple Grove, MN, is currently working properly, but had a variety of problems due to a combination of design and installation issues. Most of the problems were not unique to the geothermal heat pump system, but were general shortcomings in design and installation (e.g., in-ground piping loops inadequately protected from plugging with debris). 21.2 Lessons Learned Some of key lessons learned across the projects are highlighted in the following (see the indi- vidual case studies in Chapter 22 for details): 21.2.1 Pre-Design (Project Planning) Phase During the planning phase, it is important that the objectives of the project are clearly defined and that provisions are made for determining the project delivery approach, key

Summary of Case Studies 147 organizations involved and roles, procurement process to be used, and monitoring and evalu- ation method. Maintaining flexibility was cited as an important attribute at this stage in the process. In several cases, the selection of the renewable technologies or other features was not predetermined but was an outcome of site evaluations. Evaluations can include resource assessments, such as wind monitoring, soil samples to determine conductivity for geothermal heat pump applications, the impacts of shading due to tree canopies or other structures, and environmental or other site-specific restrictions. Other factors, such as the local utility’s view toward renewable energy projects and the impacts of rates or other regulatory factors, were cited. The availability of financial incentives to help defray system costs is another impor- tant factor in the selection of the technology. Ensuring good communication throughout the process was cited by a number of projects as a key element in successful projects. In particular, there were several instances where a miscommunication resulted in improperly sized equipment being installed, or where there was reworking of systems due to the failure to communicate plans properly. 21.2.2 Design Phase A major lesson learned was to coordinate design efforts and to make sure to properly account for the impacts of the renewable energy components on standard building design. It was found in one project that plan examiners will bump wind loads/snow loads for untested technology. Getting the key players involved early was cited as very important to smooth project devel- opment. For example, in implementing roof-mounted solar thermal or photovoltaic systems, coordination among the roofer, solar equipment installer, and electrical contractors is essential. Where there are third-party arrangements, such as power purchase agreements, the developer buys equipment, the general contractor installs, and the power purchase provider owns, oper- ates, and maintains; thus, there is an issue of coordination between the developer and installer. The determination of who completes the design depends on the capabilities of the sponsor- ing organizations and internal processes. For example, the Caltrans CREBs program found it advantageous to centralize their PV project designs and came up with strategies to expedite plan reviews with regulatory bodies (e.g., permitting authorities, fire marshal). Other organiza- tions contracted out the design and construction of their projects. In some instances, renewable energy specialists were hired as advisers for developing the design specifications. 21.2.3 Construction Phase A major lesson learned from the construction process was that close coordination and scheduling between the subcontractors is needed to avoid sequencing issues. In some instances, completed work had to be removed and then redone. In addition, more attention to testing and balancing requirements of the HVAC system would have been helpful. A major lesson learned in this phase for the Milford wind project was that while in-house staff may be able to accomplish significant portions of a small project, the use of experienced contractors in key areas is critical. 21.2.4 System Commissioning and Operation In a number of instances the desirability of planning for and implementing monitoring and evaluation was cited. This performance monitoring can be used to ensure that systems are operating as intended. It can also be used for educational purposes—to raise awareness on the part of build- ing staff or visitors—in the effectiveness of energy strategies in reducing energy operating costs or meeting environmental goals. The added costs of performance monitoring—including ongoing costs for analysis—were cited as one of the concerns with incorporating performance monitoring equipment.

148 22.1 Case Study: St. Clair, MO, Maintenance Facility Solar Thermal Systems 22.1.1 Overview The St. Clair Maintenance Facility is operated by the Missouri Department of Transportation and consists of six buildings totaling 29,800 ft2. It is located on the service road along I-44 in St. Clair, MO, west of Route 47, which has average daily traffic of 33,100 vehicles. The buildings are primarily of pre-engineered, insulated metal construction. A roof-mounted solar air heating system is used to provide supplementary heat to Building A, a 9,000-ft2 maintenance building. The principal use of Building A is vehicle maintenance (equipment storage and routine repair), with some office space, and an adjacent wash bay for vehicle washing. The facility is occupied 10 hours per day in the summer and 8 hours per day during the rest of the year. The exception is during snow emergencies, where it may operate all hours, and the portion of the facility that houses offices of the Missouri State Highway Patrol, which operates all hours. About 20 to 25 individuals work in the building. The solar air heating system consists of 40 flat plate solar air collectors (1,040 ft2 total array area) that warm air drawn from the building, which is subsequently dis- charged back into the space. In addition to the solar air heating system, there are two solar water heating systems. Each has four flat plate solar liquid collectors (128 ft2) that are mounted on each end of Building A’s roof. (See Figure 22-1.) These serve to displace electricity used by electric water heaters that serve the wash bay and domestic water needs. The solar air heating system cost was $138,000, and the solar water heaters cost $16,000, bringing the total solar project cost to $154,000. The systems are not being monitored, but based on solar panel and system rating information, it is estimated that the solar air heating system saves 215 MMBtu and $1,505 in annual operating costs, assuming natural gas unit costs of $7/MMBtu and a gas heater efficiency of 80%. From an eco- nomic perspective this equates to a payback period of 91.7 years. The water heating systems save 56.9 MMBtu and $1,167 in annual operating costs, assuming electricity unit costs of $0.07/kWh. From an economic perspective this equates to a payback period of 13.7 years. Based on fuel bills, during the summer months, the solar water heating systems supply most of the energy for water heating. Overall there is great satisfaction with the system. A similar solar air heating system has been installed at a nearby Park Service facility based on the experience with this system. C H A P T E R 2 2 Individual Case Studies Site and Building Information: Location: St. Clair, MO • Address: 2273 North Service Rd. East St. Clair, MO 63077

Individual Case Studies 149 22.1.2 Project Development Process 22.1.2.1 Pre-Design (Project Planning) Phase In planning for the construction of the new Building A, it was decided to incorporate green or sustainability features that were considered practical (e.g., economical). Operating cost savings were a major factor in considering various options. The use of renewable energy resources, including wind and solar, were suggested, as were water-retention strategies. Wind was eliminated due to inadequate wind resource, and water retention was eliminated due to the potentially high costs and long paybacks due to difficulties in excavating in a rock shelf. Solar systems for space heat- ing and water heating were evaluated and determined to be economical based on the energy savings of the systems. At the time, natural gas prices had been particularly volatile and were coming down from new highs. Building A was designed to meet the needs of the current fleet Source: J. E. Foster Building Company. Figure 22-1. Solar air collector array (foreground) and one of the solar water heating system collector arrays (rear row). • Tel.: 636-629-2697 • ASHRAE climate zone: 4A • Annual heating degree days (65°F base): 4,758 • Average high temperature/low temperature (summer): 87.3°F/68.0°F • Average high temperature/low temperature (winter): 40.6°F/24.0°F • Average Annual precipitation: 37.5 in. • Building A floor area: 9,000 ft2 (7,950 ft2 conditioned) • Occupancy: 20 to 25 • Schedule: 10 h/day summer; 8 h/day rest of year Renewable Energy Features: • Solar air heating system: Serves Building A maintenance bay area and office. • Solar water heating systems: One system provides domestic water, and the second system is used for vehicle washing. • Solar heating for Building E: Supplies all heat for the 1,500-ft2 fabrication shop. • Daylighting for cold storage buildings: Two pole barns have glazed panels in the upper portion of the exterior walls to allow daylight into the building.

150 Renewable Energy Guide for Highway Maintenance Facilities and Missouri DOT operations, and was most suitable for placement of the roof-mounted solar collectors. The construction of the new building and the solar system was part of an overall site development plan that had been in the works for 11 years. It included the renovation of Building D (including significant energy upgrades) and its conversion from a vehicle maintenance facility to a bridge maintenance facility. A fabrication shop, Building E, was also constructed, which was to be heated by its own solar array. Given the highly visible location of the site (near a major roadway), the addition of the solar systems provided a good opportunity to showcase Missouri DOT’s efforts in incorporating green/renewable energy features. The project team consisted primarily of the Missouri DOT regional staff, which developed the basic functional requirements for the buildings. In general, Missouri DOT uses its in-house designers for all their projects. A design–bid–build approach was used, with in-house Missouri DOT staff being the lead designers with assistance from G2 Power Technologies, LLC, a solar firm, on the design specifications for the solar thermal systems. The solar systems were bid competitively based on performance specifications, although there were no specific energy-monitoring equip- ment requirements. The funding for the project was from Missouri DOT capital improvement budgets, and there was no special financing and no incentives involved. According to Ed Warhol, one of the main designers for the project, “This was a very successful process. The area team, design, and facilities work hard to make this process work. Communication was a very important part of this process.” An important lesson from the planning state is to be flexible and look at various options, recognizing that one size does not fit all. 22.1.2.2 Design Phase The design team consisted of Missouri DOT staff with support from G2 Power Technologies, LLC, for the design and specification of the solar air heating and hot water systems. The solar air heating system capacity (number of panels) was based on the estimated requirements for the floor area being served and the collector output (per manufacturer). The result was a system of consisting of six panels (in pairs) per zone serving five zones within the main maintenance area, and 10 panels (in pairs) serving the office area (see Figure 22-2). Source: Dan Poett, G2 Power Technologies, LLC. Figure 22-2. Layout of solar air collectors on roof of Building A.

Individual Case Studies 151 The solar water system capacities (number of panels and size of storage tanks) were estimated based on the number of people and vehicle washes (see Figure 22-3). There was no information on the amount of hot water used, either for domestic purposes or for vehicle washing. The final system design—solar air heating and water heating systems—was consistent with the design concept. There were no significant changes during the design process. It was not until the construction period—but prior to installation of the solar systems—that some design changes needed to be made. The major lessons learned were to coordinate design efforts and to make sure to properly account for the impacts of the renewable energy components on standard building design. This includes structural considerations such as dead loads and wind loads associated with the collectors, solar collector array attachments, and roof and wall penetrations. Figure 22-3. Schematic of solar water heating system. Source: Dan Poett, G2 Power Technologies, LLC.

152 Renewable Energy Guide for Highway Maintenance Facilities 22.1.2.3 Construction Phase The construction contract was awarded to J. E. Foster for the overall building project. A subcontract was awarded to G2 Power for both the solar air heating system (SolarSheats equipment—by Your Solar Home) and the two solar water heating systems (Eagle Sun Systems by AET Technologies). This covered both the equipment and the installation. Some changes to the design (as-built) were required due to differences in the roofing system and mounting requirements of the solar collectors. These included the following: • Supporting of the panels to the roofing system. Placement of the structural support members for attachment of the solar panels. • Roofing system panel sizes. Due to the penetration of the ducts, the panel sizes were larger than normal to prevent cutting of the ribs. • Attachment of the solar panels to the roofing systems was an issue. The metal building was ordered from one manufacturer and the solar panels from another, and the actual attachment detail was unknown. This was reviewed prior to any installation and worked out before any issues developed. The systems were straightforward in terms of design and operating requirements. There were no complicated control systems and interfaces to deal with. Formal commissioning was not performed. The J. E. Foster Building Company performed a complete walk-through with Missouri DOT staff and provided a 1-year warranty. The lessons learned include: • Make sure proper planning is done and any issues are ironed out before design begins. This occurred on this project and helped flag potential problems and helped with timely imple- mentation of solutions. Project Team Building Owner’s Representative Representative from Missouri DOT Design Senior Facilities Designer Missouri DOT Senior Facility Operations Specialist Missouri DOT General Services Facilities Manager Missouri DOT Design Solar Design Adviser Representative from G2 Power Technologies, LLC Construction General Contractor J. E. Foster Building Company Solar System Supplier/Installer G2 Power Technologies, LLC Equipment Manufacturer Solar air system: Your Solar Home Solar water heaters: AET Technologies, Inc. Mechanical Contractor J. E. Foster Building Company Scott-Lee Heating and Cooling Construction Oversight Missouri DOT Commissioning: N/A

Individual Case Studies 153 • Make sure there is good communication among all the team members. For example, commu- nication between the solar panel manufacturer and the roofing manufacturer for penetration and attachment information helped ensure that the installation was successful. Figure 22-4 through Figure 22-8 show various aspects of the systems during and after installation. 22.1.3 Results The systems appear to be operating well, although they have not been instrumented to provide energy performance data. It may be worthwhile to compare the overall building energy use (e.g., natural gas) to similar facilities in the area. However, comparing electric energy use (e.g., savings from the solar water heaters) would be difficult since the complex is master-metered, as are other similar operations. The solar water heaters have been able to provide enough hot water without the need to operate the electric heating elements for much of the time. The solar air heating system provides warm air that is reducing the need for unit heater operation. Quantifying the economics of the systems is not possible due to the lack of system performance data. The systems Source: Ed Warhol, Missouri DOT. Figure 22-4. Solar collectors for water heating on each end of Building A. Source: Ed Warhol, Missouri DOT. Figure 22-5. Solar collectors for water heating.

154 Renewable Energy Guide for Highway Maintenance Facilities Source: J. E. Foster Building Company. Figure 22-8. Ductwork/interior of Building A. Figure 22-6. Solar collectors for water heating and mounting structure for solar air collectors (foreground). Source: Ed Warhol, Missouri DOT. Figure 22-7. Solar air collector array. Source: J. E. Foster Building Company.

Individual Case Studies 155 are not being monitored, but based on solar panel and system rating information it is estimated that the solar air heating system saves 215 MMBtu and $1,505 in annual operating costs, assuming natural gas unit costs of $7/MMBtu and a gas heater efficiency of 80%. From an economic perspec- tive, this equates to a payback period of 91.7 years. The water heating systems save 56.9 MMBtu and $1,167 in annual operating costs, assuming electricity unit costs of $0.07/kWh. From an economic perspective this equates to a payback period of 13.7 years. Based on fuel bills, during the summer months, the solar water heating systems supply most of the energy for water heating. Overall there is great satisfaction with the system. A similar solar air heating system has been installed at a nearby Park Service facility based on the experience with this system. The system maintenance requirements are fairly routine, involving checks of filters and pump and blower operation. A minor maintenance issue that was encountered was the need for more frequent filter changes on the air distribution system, due to the presence of welding, fabrication, and truck exhaust. The solar hot water system circulation pumps also needed to be replaced, either due to debris in the lines or air in the system. These were replaced (in part) under system warranty. The maintenance is provided by Missouri DOT staff with assistance from an on-call service company. No specialized maintenance services have been required. Solar Air Heating System for Building A • Solar collector type: flat plate air, SolarSheat 1500 GS, manufactured by Your Solar Home, Inc. • Solar collector array area: 1,040 ft2 (40 collectors) • Heat transfer medium: air • Freeze protection: none required • Over-temperature protection: none • Thermal storage: none • Primary heating: natural gas-fired unit heaters for garage area • System cost: $138,000 • Annual energy savings: 215 MMBtu • Annual energy operating cost savings: $1,505 • Economics: 91.7 years (payback period) • Applicability: buildings that have space heating requirements with warm air distribution systems Solar Water Heating Systems for Building A • Solar collector type: flat plate liquid, EagleSun System • Solar collector array area: 256 ft2 (two systems, four collectors each) • Heat transfer medium: water • Freeze protection: closed-loop drain-back system • Over-temperature protection: closed-loop drain-back system • Thermal storage: 80 gallon tank (domestic water)/120 gallon tank (vehicle wash) • Supplemental heating: 4,500 kW electric element in tanks • System cost: $16,000 (two systems) • Annual energy savings: 56.9 MMBtu • Annual energy operating cost savings: $1,167 • Economics: 13.7 years (payback period) • Applicability: all buildings with water heating loads

156 Renewable Energy Guide for Highway Maintenance Facilities 22.1.4 Lessons Learned • Communication between the solar panel manufacturer and the roofing manufacturer for penetration information and attachment is very important. Make sure that the shop drawing information is reviewed as soon as possible, as was done on this project. • The hot air circulation system does provide some heated air, reducing the need for supplemental heating. Unfortunately, the end users do not really experience this due to the location of the air distribution outlets at the ceiling line. • Solar hot water systems work well and are recommended applications. • Add provisions for monitoring the performance of the system, depending on costs. 22.1.5 Future Plans There are no specific plans to build similar systems at other Missouri DOT locations at this time. 22.2 Case Study: Fort Drum, NY, Solar Ventilation Air Heating System on Maintenance Facilities 22.2.1 Overview The U.S. Army’s Fort Drum near Watertown, NY, has applied solar ventilation air heating systems to 27 existing vehicle maintenance buildings to help reduce energy operating costs and meet Army energy and environmental objectives. Since 2006, more than 110,000 ft2 of solar collectors have been installed. The buildings selected for the solar applications generally have large south-facing (or southeast/southwest) wall areas that are best suited for mounting the solar collectors and maximizing exposure to the sun, and they have large requirements for fresh air. The solar ventilation air heating technology uses a perforated corrugated metal cladding (e.g., painted galvanized steel) as the solar collector. This unglazed transpired solar collector (trade name SolarWall, supplied by Conserval) is typically installed on the south-facing vertical surfaces of the building. It is attached to the walls by framing materials, which are spaced to provide optimized channels for airflow between the collectors and the wall. Outside air is drawn across the collectors from the bottom to the top and into the building by ventilation fans. This air is then ducted into the building’s existing air distribution network or directly into the space. The system provides solar-heated air whenever the collectors are sufficiently warmed by the sun and there is a need to heat the ventilation air. The systems generally heat the air to a temperature of 20°F to 60°F above the outside temperature. This temperature rise is based on the amount of sunshine available and the ventilation airflow rate. In addition to providing solar-heated air, the system can help destratify air in high bay areas and recapture heat that would ordinarily be lost through the walls. In the summer, the collectors can help shield the wall from the sun, reducing cooling needs. While actual performance data on the systems are not available, it is estimated that the annual output of all of the systems is on the order of 31,022 MMBtu. This figure includes the solar contributions and the heat loss captured by the system and destratification. This results in a natural gas savings of 44,317 MMBtu, assuming a gas heater efficiency of 70%. The avoided greenhouse gas (GHG) reductions are about 2,000 tons of carbon dioxide equivalent (CO2e) annu- ally. The cost of all the systems was $3.4 million, or an average of about $31/ft2 of collector installed. There were no financial incentives used to reduce the cost of the system. Based on a natural gas cost of $9/MMBtu, the annual operating cost savings are $398,853, and the estimated payback period is 8.5 years. The systems have generally been working well, with some valuable lessons learned regarding fan selection, fan noise, placement and type of air intake and distribution, and controls. Figure 22-9 shows a representative building facade with the unglazed transpired solar collectors, while Figure 22-10 provides a schematic that illustrates the general operation of these types of systems.

Individual Case Studies 157 Source: Conserval: http://solarwall.com/media/download_gallery/ FortDrum-SolarWall.pdf. Figure 22-9. Fort Drum Vehicle Maintenance Garage (P-10670) with unglazed transpired collectors (SolarWall) installed above garage doors. Source: Conserval. SOLARWALL PANELS AIR SPACE TO DISTRIBUTION SYSTEM SUMMER BYPASS HVAC SYSTEM Figure 22-10. Unglazed transpired collector (SolarWall) operation.

158 Renewable Energy Guide for Highway Maintenance Facilities 22.2.2 Project Development Process 22.2.2.1 Pre-Design (Project Planning) Phase The project was motivated in large measure by the need for a cost-effective means to reduce Fort Drum’s energy operating costs and to reduce greenhouse gas emissions. In addition, it was viewed as an opportunity to improve and upgrade ventilation systems. Given the large number of buildings that had substantial requirements for ventilation air, means to reduce the energy for heating this air were explored. The SolarWall system, which uses unglazed transpired collectors, was identified as a promising candidate for heating ventilation air. The Fort Drum energy manager had knowledge of the technology through other installations, and based on initial estimates, thought it would be a good application. He worked closely with the Army Corps of Engineers to develop the project. The Energy Conservation Invest- ment Program (ECIP) was tapped as the funding source. ECIP is an internal U.S. Depart- ment of Defense program that was established to promote projects that reduce energy use. However, since it has a limited budget, projects are awarded through internal competition. The SolarWall system, manufactured by Conserval Systems, Inc., was identified as the sup- plier due to its established position with the technology. The contracting for the project was based on a specification developed by the energy manager, the Army Corps of Engineers, and Conserval as a design–build project. 22.2.2.2 Design Phase The systems were designed through close cooperation between the Fort Drum energy manager, the Army Corps of Engineers, and Conserval staff. Since there were a large number of buildings with different facades and ventilation systems, a number of different designs were developed. Some buildings required improvements to the ventilation systems to provide for more controlled ventilation. Integration with existing ventilation systems and the current requirements of the buildings were key focuses, as were ensuring occupant comfort. This required some customization of the design solutions and specifications of different equipment (e.g., types of fans/drives, types of dampers used, and controls). For example, designs that would help reduce space temperature gradients by mixing higher temperature air near the roof with solar-heated ventilation air were developed. The objective was to lower the temperatures near the roof, thereby reducing heat loss, Site and Building Information: Location: Fort Drum, New York • Address: Fort Drum, NY 13602 • ASHRAE climate zone: 6A • Annual heating degree days (65°F base): 7,289 (Watertown AP) • Average high temperature/low temperature (summer): 76.1°F/54.2°F • Average high temperature/low temperature (winter): 33.2°F/13.9°F • Average annual precipitation: 37.3 in. • Occupancy: varies by building • Schedule: varies by building • Ventilation air requirements: 300,000 cfm (27 buildings) • Renewable energy features: solar ventilation air preheating using unglazed transpired collectors (SolarWall) • Other energy/sustainability features: Various energy projects have been instituted including geothermal heat pumps in some buildings.

Individual Case Studies 159 while improving overall comfort through more even heating and distribution of air. The possible intake of vehicle exhaust fumes entering through the collectors was also considered, particularly when parking areas were adjacent to the proposed collector mounting area. The SolarWall colors were selected to best match the facade of the particular building. While a black collector is the most beneficial from a heat collection standpoint, other dark colors can still provide good performance. Project Team Fort Drum Energy Manager Fort Drum Design Conserval Systems, Inc. Conserval Engineering, Inc. Construction Installation Contractor Conserval Engineering, Inc. Solar Collector Manufacturer Conserval Engineering, Inc. Construction Oversight Army Corps of Engineers Commissioning Army Corps of Engineers Conserval Engineering, Inc. 22.2.2.3 Construction Phase Project construction was performed by Conserval, with oversight provided by the Army Corps of Engineers. The project proceeded in phases over the approximately 18-month con- struction period. The installation was accomplished primarily by two sheet metal workers and two electricians. There were some issues uncovered during the construction period, including noise associated with certain installations (depending on type of fan and location), comfort issues related to the type of intake (gravity-type intake dampers), which caused the relatively cold air from the system to be directed too close to building occupants, and control operation/sequencing. Figure 22-11 shows the construction of the solar wall support structure, while Figure 22-12 shows the completed system. Figure 22-13 is an interior view of the building, showing a ducted distribution system. Figure 22-14 shows a building with a ductless air distribution approach. 22.2.3 Results One of the systems was monitored (Shop Building 91, with 4,100 ft2 of collectors); however, only limited data collection was performed. Additional data monitoring activities have been launched, and it is expected that performance information on the building will be available over the next year. In the meantime, estimates from performance models and the limited monitoring indicate that the SolarWall systems provide about 31,022 MMBtu of heat. This figure includes the solar contributions and the heat captured that would ordinarily be lost through the walls, as well as destratification savings. This results in a natural gas savings of 44,317 MMBtu, assuming a gas

160 Renewable Energy Guide for Highway Maintenance Facilities Source: Conserval, John Hollick. Transpired Air Heaters in a Cold Weather Application, presentation at Energy Smart Expo, March 28, 2008. Figure 22-11. Framing structure for SolarWall on Shop Building 91 at Fort Drum. Source: Conserval, John Hollick. Transpired Air Heaters in a Cold Weather Application, presentation at Energy Smart Expo, March 28, 2008. Figure 22-12. SolarWall installed on Shop Building 91 at Fort Drum. Source: Conserval, John Hollick. Transpired Air Heaters in a Cold Weather Application, presentation at Energy Smart Expo, March 28, 2008. Figure 22-13. Distribution system using flexible ducts with existing system. Figure 22-14. Installation using ductless fan. Source: Conserval, John Hollick. Transpired Air Heaters in a Cold Weather Application, presentation at Energy Smart Expo, March 28, 2008.

Individual Case Studies 161 22.2.4 Lessons Learned • Fan noise may be an issue in some cases, so measures to dampen the noise should be taken. Solutions include use of variable-speed drives to reduce speed, adding silencers, and adding duct insulation for ducted systems. • Gravity dampers for outside air intake should be avoided to eliminate the downward flow of cold air. • Distribution ductwork should be added, if not already in place, to ensure better distribution of air, to reduce noise, and for overall comfort. • Consider connecting to existing direct digital control systems, if available. This can provide better year-round operational control. 22.2.5 Future Plans • Additional buildings with SolarWall are being considered. • Performance monitoring of one system has just begun. 22.3 Case Study: Plattsburgh, NY, Solar Ventilation Air Heating System on Airport Facilities 22.3.1 Overview The Plattsburgh International Airport in Plattsburgh, NY, installed a total of 17,840 ft2 of SolarWall two-stage ventilation air systems on four existing buildings in 2011. The buildings include three 28,000-ft2 hangars, designated as Hangars 3, 4, and 5, and a 26,500-ft2 industrial Solar Ventilation Air Heating System Information • Solar collector type: unglazed solar transpired collector (SolarWall) • Solar collector array area: 110,000 ft2 (27 buildings, 50 systems) • Backup ventilation heater: varies—gas-fired heaters • System cost: $3,400,000 • System cost per unit collector area: $31/ft2 collector • Annual system output: 31,022 MMBtu (solar heat and captured heat from buildings and destratification benefits) • Annual system output per unit collector area: 0.282 MMBtu/ft2 collector • Annual energy savings: 44,317 MMBtu (assumes 70% efficient gas-fired heaters) • Annual energy operating cost savings: $398,853 (@$9/MMBtu natural gas) • Economics: 8.5 years (payback period) • Applicability: buildings that have high ventilation air requirements, ample south (or near south) oriented wall area, and are in moderate-colder regions heater efficiency of 70%. The avoided greenhouse gas reductions are about 2,000 tons of CO2e annually. The associated annual energy operating cost savings are estimated to be $398,853. The estimated payback period is 8.5 years. The systems have generally been working well, with some valuable lessons learned regarding fan selection, fan noise, placement and type of air intake and distribution, and controls.

162 Renewable Energy Guide for Highway Maintenance Facilities facility, designated as the Trans-Ed building. The airport is a former military installation (Plattsburgh Airport Base) that was converted to private-sector use in 2008, as a result of the federal government’s divestments under the Base Realignment and Closure Act (BRAC). The primary objective of the project was to reduce heating bills in order to keep rental costs competitive. The traditional solar ventilation air heating technology, which has been in use for over 20 years, uses a perforated corrugated metal cladding (e.g., painted galvanized steel) as the solar collector. Conserval had recently developed a new, two-stage transpired solar collector system, and Plattsburgh International Airport was willing to demonstrate the new technology with the New York State Energy Research and Development Authority’s (NYSERDA’s) support. The two-stage system operates with the lower half of the wall constructed as a traditional transpired collector, which acts as the first stage. The solar preheated air then enters the top portion of the unit (second stage), which has the transpired collector covered by a clear plastic (polycarbonate) glazing. This transpired collector (SolarWall, supplied by Conserval) is typically installed on the south-facing vertical surfaces of the building. It is attached to the walls by framing materials, which are spaced to provide optimized channels for airflow between the collectors and the wall. Outside air is drawn across the collectors from the bottom to the top and into the building by ventilation fans. The air is heated as it passes across the unglazed portion of the collectors and heated even more as it passes through the glazed portion. This air is then ducted into the building’s existing air distribution network or directly into the space. The system provides solar-heated air whenever the collectors are sufficiently warmed by the sun and there is a need to heat the ventilation air. The single-stage system was designed to heat air up to 50°F above ambient. The two-stage system is now heating the air to a temperature of 36°F to 85°F above the outside temperature; recent monitored data show gains of over 100°F above ambient. This temperature rise is based on the amount of sunshine available and the ventilation airflow rate. In addition to providing solar- heated air, the single system could help to destratify air in high bay areas and recapture heat that would ordinarily be lost through the walls. With higher delivered air temperatures from the two-stage system, the method of achieving the destratification savings may require modifications for future designs. In the summer, the collectors can help shield the wall from the sun, reducing cooling needs. Hangar 3 is currently being monitored for performance. Based on preliminary data from January 9, 2012, through February 24, 2012, it is estimated that the annual output of the 3,500-ft2 collectors will be on the order of 365 MMBtu, or 0.104 MMBtu/ft2. This figure includes the contributions of the solar and building heat loss recapture, but not the savings from destrati- fication. This results in a natural gas savings of 521 MMBtu, assuming a gas heater efficiency of 70%. Based on the delivered natural gas cost of $12/MMBtu, at the time of the proposal, the annual operating cost savings from the hangar was projected to be $6,252. The avoided greenhouse gas reductions are 42,607 pounds of CO2e annually. The cost for the Hangar 3 system was $121,606. The lack of destratification savings means that the solar portion of savings results in an estimated payback period of 19 years. It is estimated that had the destratification changes been imple- mented in Hangar 3 from the outset, they would have increased the annual natural gas savings to 840 MMBtu. With destratification, the payback period would be expected to drop to the 11-year range. However, the entire $614,219 cost of the project (all four buildings) was covered by a $621,000 grant from NYSERDA. The funding to NYSERDA originated with the U.S. DOE and the American Recovery and Reinvestment Act (ARRA) of 2009. One of the most valuable lessons learned with this project was how best to configure and operate the two-stage system for future installations. This strategy is now being tested at another installation. Figure 22-15 shows the two-stage transpired solar collectors, with the unglazed portion on the lower section of the wall. Figure 22-16 illustrates how the two-stage design operates.

Individual Case Studies 163 Source: Conserval. Figure 22-15. Hangar with unglazed transpired collectors (two-stage SolarWall). Figure 22-16. Two-stage unglazed transpired collector (SolarWall) operation. Source: Conserval

164 Renewable Energy Guide for Highway Maintenance Facilities 22.3.2 Project Development Process 22.3.2.1 Pre-Design (Project Planning) Phase The airport manager was exploring ways to reduce energy operating costs in order to make hangar rental fees attractive. Due to the severe winter climate, heating costs were a major contributor to facility operating expenses. He met with a representative of Conserval Systems to determine if the SolarWall unglazed transpired collector systems would provide a good solution for reducing his heating costs. Conserval provided the analysis, which indicated that four of the buildings were good candidates and would be economical for installation. The RETScreen soft- ware tool from NRCAN was used to estimate the energy provided by the systems. Based on this information, the airport manager applied for a competitively sourced grant from NYSERDA. This funding originated with the U.S. DOE based on ARRA funds. The NYSERDA program was targeted at municipalities and focused on energy savings projects. The city of Plattsburgh applied for and received two grants totaling $621,000. A design–build approach was used to implement the project, with the airport issuing a competitive solicitation to perform the work. Dynamic Construction was selected with a bid of $614,219. 22.3.2.2 Design Phase The design for the project was based on the information initially developed by Conserval, with small modifications made by Dynamic Construction to fit the specific building requirements. The changes were due to the presence of a crane in one of the hangars, which interfered with the air distribution duct work. The result was a change to one of the fans and a reduction in the solar collector area of a few hundred square feet. Table 22-1 summarizes some of the design features and costs. The design phase was completed within 3 weeks of project award. Overall project management was performed by the airport manager, with design–build responsibility with Dynamic Construction. Conserval performed as advisers on the design. Building Description Size of SolarWall Number of Fans and Design Flow Rate Total Installed Cost Cost per ft2 Installed Estimated Payback (Years) Hangar 3 3,500 ft2 2 fans @ 2,000 cfm ea $121,606 $34.75 11 Hangar 4 3,500 ft2 2 fans @ 2,000 cfm ea $121,606 $34.75 11 Hangar 5 6,000 ft2 3 fans @ 3,000 cfm ea $200,631 $33.33 10 Trans-Ed 4,840 ft2 3 fans @ 3,000 cfm ea $170,376 $35.20 10 Table 22-1. Project design features and costs. Site and Building Information: Location: Plattsburgh, New York • Address: 137 Margaret St., Plattsburgh, NY 13642 • ASHRAE climate zone: 6A • Annual heating degree days (65°F base): 7,817 (Plattsburgh Airport) • Average summer max/min temperature: 79.8°F/54.6°F • Average winter max/min temperature: 25.6°F/6.7°F • Average annual precipitation: 34.43 in. • Floor area: 110,500 ft2 (3 to 28,000 ft2 hangars and 1 to 26,500 ft2 industrial/ maintenance building) • Occupancy: varies by building • Schedule: varies by building • Renewable energy features: solar ventilation air preheating using two-stage unglazed transpired collectors (SolarWall) • Other energy/sustainability features: none

Individual Case Studies 165 22.3.2.3 Construction Phase Project construction was performed by Dynamic Construction, including installation of the SolarWall, fan duct work, controls, and electrical work. The project was completed using Davis-Bacon Act wages. In order to install SolarWall on the hangars, Dynamic needed two vertical lifts, an electric scissor lift, and a forklift (see Figures 22-17 and 22-18). The systems for Hangars 4 and 5, as well as the Trans-Ed building, took 4 weeks to install, while Building 3 took 6 weeks. This was followed by a 2-week monitoring and installation period. The entire project took 5 months from the time the NYSERDA grant was awarded until the systems became operational. 22.3.3 Results The Cadmus Group, Inc., as part of an evaluation of NYSERDA’s ARRA-funded renewable energy projects, began performance monitoring of the Plattsburgh Airport SolarWall project in 2011. The monitoring includes: • Fan electricity consumption; • SolarWall delivery temperature, humidity, and airflow; Project Team Owners Representative Airport Manager (former) Plattsburgh International Airport Design Conserval Systems, Inc. Construction Installation Contractor Dynamic Construction Solar Collector Manufacturer Conserval Systems, Inc. Source: Conserval. Figure 22-17. Construction of unglazed two-stage SolarWall showing support framing and installation of polycarbonate glazing.

166 Renewable Energy Guide for Highway Maintenance Facilities • Outdoor air temperature and humidity; • Incident solar radiation; and • Indoor air temperature at 5-ft, 19-ft, and 33-ft heights. Based on these measurements, Conserval was able to calculate energy savings due to preheated air delivery, destratification, and reduced heat loss through the building envelope. Shortly after monitoring began, it was discovered that the controls schedule for summer/winter operation had been reversed. This appears to have happened during the replacement of some broken sensors during installation. This was fixed before the winter season. Using data collected between January 9, 2012, and February 24, 2012, Conserval estimated that the annual output of the 3,500-ft2 collectors on hangar 3 will be on the order of 365 MMBtu. This figure includes the contributions of the solar and building heat loss recapture, but not the savings from destratification. This results in a natural gas savings of 521 MMBtu, assuming a gas heater efficiency of 70%. Based on the delivered natural gas cost of $12/MMBtu, at the time of the proposal, the annual operating cost savings from the hangar was projected to be $6,252. The avoided greenhouse gas reductions are about 21 tons of CO2e annually. The cost for the Hangar 3 system was $121,606, which results in an estimated payback period of 19 years. However, the entire $614,219 cost of the project (all four buildings) was covered by the NYSERDA grant. The systems have been working well and have actually provided a temperature rise in excess of 100°F, exceeding expectations (see Table 22-2 and Figure 22-19). It has been observed that the buildings now take only 45 min to reheat versus 3 hours before the system was installed. Source: Conserval. Figure 22-18. Completed two-stage SolarWall installation. Solar Ventilation Air Heating System Information • Solar collector type: unglazed transpired solar collector (two-stage SolarWall) • Solar collector array area: 17,840 ft2 (four buildings) • Monitored Building 3 solar collector array area: 3,500 ft2 • Backup ventilation heater: gas-fired heaters • Total system cost: $614,219 (without grant, $0 including grant) • Monitored Building 3 system cost: $121,606

Individual Case Studies 167 22.3.4 Lessons Learned The two-stage SolarWall provided higher temperatures than expected at the flow rates and levels of solar radiation measured. However, the current system is not configured to take advantage of the relatively high-temperature solar-heated air. As designed, the solar-heated air is distributed by the blowers to the space through ductwork and dampers at the ceiling level. At this high distribution point, the solar-heated air cannot effectively fall to the occupant level because it has a higher temperature (lower density) than the room air. This negates its value in destratifica- tion. An alternative would be to use less expensive wall fans with variable-speed drive motors to modulate airflow to provide 65°F to 80°F air. The fans would introduce this solar-heated fresh air into the area below the ceiling without the expense of ductwork. Instead, large high-velocity, low-speed destratification fans would be used. These fans typically can destratify air over a 1,500-ft2 • Total system cost per unit collector area: $34.43/ft2 collector • Annual system output: 365 MMBtu (solar heat and captured heat from monitored Building 3) • Annual system output per unit collector area: 0.104 MMBtu/ft2 collector • Annual energy savings: 521 MMBtu (monitored Building 3 only—assumes 70%-efficient gas-fired heaters) • Annual energy operating cost savings: $6,252 (monitored Building 3 only— assumes $12/MMBtu natural gas • Economics: 19 years (payback period without grant) • Applicability: buildings that have high ventilation air requirements, ample south (or near south) oriented wall area, and are in moderate-colder regions Time (Eastern Daylight Time) SolarWall Temp (°F) Ambient Temp (°F) Solar Rad (W/m2) Temp Rise (°F) Airflow (cfm) 07:30 40.04 20.80 28.6 19.2 1,008 08:00 71.5 23.3 64.7 48.3 1,841 08:30 93.8 30.2 190.3 63.6 1,961 09:00 111.4 31.7 256.5 79.6 1,943 09:30 126.5 31.2 318.9 95.3 1,870 10:00 132.2 32.4 371.5 99.8 1,962 10:30 138.2 27.8 414.4 110.3 1,951 11:00 137.1 28.0 417.8 109.1 1,941 11:30 136.7 27.0 449.1 109.6 1,864 12:00 133.6 26.2 461.9 107.4 1,747 12:30 124.6 25.3 453.8 99.3 1,714 13:00 112.9 24.0 434.1 88.9 1,769 13:30 104.0 23.8 400.8 80.2 1,776 14:00 92.6 23.7 357.0 68.9 1,803 14:30 79.8 23.7 304.0 56.1 1,768 15:00 66.7 23.5 246.1 43.2 1,776 15:30 55.0 23.1 182.5 31.9 1,642 16:00 44.2 22.1 116.8 22.1 1,466 16:30 37.5 21.1 44.3 16.4 1,045 17:00 35.5 20.1 8.4 15.4 502 Average 93.7 25.4 276.1 68.2 1,667 Source: Conserval. Table 22-2. Representative performance data—February 4, 2012.

168 Renewable Energy Guide for Highway Maintenance Facilities to 3,000-ft2 floor area, depending on the height. They would be controlled (on/off) based on the temperature of the air below the ceiling. It is estimated that had these changes been implemented in Hangar 3 from the outset, they would have increased the annual natural gas savings to 840 MMBtu. Other lessons learned are: • If available, connect the system to existing direct digital control systems/building automation systems. This can provide better year-round operational control. If this is not available, then use the simple time clock control provided. Make sure to install some sort of lockbox to prevent tampering with the settings. • Introduce performance monitoring earlier in the process as a means of confirming perfor- mance and identifying any issues. 22.4 Case Study: Coney Island, NY, Train Maintenance Facility Solar Water Heating System 22.4.1 Overview The Coney Island Train Maintenance Facility, located in Brooklyn, NY, sits on approximately 75 acres of land that serves as a major maintenance hub for the New York Metropolitan Trans- portation Authority (MTA)–New York City Transit (NYCT) trains. The main buildings include the 360,000-ft2 maintenance barn, a 37,500-ft2 electric motor repair shop, a 30,000-ft2 pneumatic repair shop, and storage areas and other specialty buildings. The facility operates year round and has 1,200 employees. Over the past few years, a number of energy efficiency and renewable energy projects have been undertaken, under the auspices of MTA–NYCT, through arrange- ments with the New York Power Authority (NYPA). NYPA is the electric power provider. In 2010, a solar water heating system was installed on the maintenance barn and was designed to meet the majority of the hot water needs of the facility. The hot water is used for washing the trains— about 50,000 vehicle washes per year—and for domestic hot water uses. The solar system consists of 1,762 ft2 of evacuated-tube collectors that heat the water up to temperatures as high as 190°F. Source: Conserval. Figure 22-19. Representative performance data—February 4, 2012.

Individual Case Studies 169 The evacuated-tube solar collectors provide higher temperature water and more efficient operation in colder ambient conditions than flat plate solar collectors. The collectors, which were specially designed to meet the wind load standards of the New York State code (120-mph equivalent wind load), are installed on the roof of the building. Solar-heated water is stored in the 2,500-gal tank that was formerly the 240-kW electric resistance storage water heater. The solar system displaces approximately 104,000 kWh of electricity annually (67% of the estimated hot water load of 156,000 kWh) and reduces electric demand by about 217 kW. When solar-heated water is either not available or insufficiently warm to meet the requirements, a new natural gas-fueled instantaneous steam water heater is used. The system cost $564,905, not including the $150,000 grant from NYSERDA. In addition, NYPA provided the financing for the system. The MTA pays off the system over time through bill payments. The estimated payback period is 5.6 years (no incentives) or 4.1 years (with incentives) based on an estimated savings of approximately $100,000 per year. The system has been performing up to expectations. Lessons learned include ensuring that the installation contractor understands any special equipment requirements (e.g., connections to special collector fittings) and specifications (e.g., nomenclature for pressure vessel specifications to ensure proper sizing), and collector stagnation-related issues (e.g., ensuring that the system is properly filled and purged of air upon start-up). Based on the posi- tive experience with this system, the MTA is planning to implement similar solar thermal projects at other sites. Figure 22-20 shows the solar collectors installed on the facility. Source: New York Power Authority, 2011. MTA Coney Island Train Yard, Vacuum-Tube Solar Hot Water System Final Report, NYSERDA, Agreement No. 9915, Appendix – April 2010 Progress Report, p. 2. Figure 22-20. Solar collector array on the roof of the MTA Coney Island maintenance barn. Site and Building Information: Location: Brooklyn, New York • Address: Brooklyn, NY 11224 • ASHRAE climate zone: 4A • Annual heating degree days (65°F base): 4,910 (La Guardia AP) • Average high temperature/low temperature (summer): 80.3°F/65.5°F

170 Renewable Energy Guide for Highway Maintenance Facilities 22.4.2 Project Development Process 22.4.2.1 Pre-Design (Project Planning) Phase The project was conceived as a result of an energy audit/assessment performed by NYPA, the organization that provides MTA with electric power. Electric water heating was identified as a good target for operating cost savings. Monitoring of the hot water heater electricity consumption/ loads was performed to provide a baseline for energy use. Solar water heating was screened and determined to be potentially economical for the application. The principal objectives of the solar water heating project were to reduce energy operating costs and provide environmental benefits (e.g., greenhouse gas reductions). This also helped meet the MTA’s broader policy goals regarding sustainability. MTA signed an agreement with NYPA in 2009 to proceed with the project. MTA had already engaged NYPA on several other projects (e.g., efficient lighting upgrades), so there was already a good working relationship. The planning team consisted of NYPA and the MTA Energy Management Organization and facilities staff. The team decided on a design–bid–build process. The financing for the project was to come from NYPA’s energy efficiency program. The program allows the customer to pay for the system through utility bill payments over terms of up to 20 years. The payments are structured so that they are offset by the projected reductions in energy operating costs due to the system. For the Coney Island project, the term was set at 10 years. MTA participated in the program to eliminate the need for MTA capital funds. In addi- tion, NYSERDA was identified as a potential source for incentives (ultimately a $150,000 grant). General requirements for system performance evaluation based on NYSERDA and MTA were formulated. 22.4.2.2 Design Phase The design was led by NYPA, in close coordination with the MTA Energy Management Organization, and facilities staff. A major area of focus was the structural requirements that a roof-mounted system would pose, as were concerns about roof maintenance and minimizing roof leaks. For this reason, a ballasted support structure was decided on. The roof was carefully analyzed to identify the areas where the ballasts/supports could be safely located. In addition, the collectors had to be able to withstand wind loading equivalent to 120 mph, so this was included in the specification. The design documents and specifications were packaged into a request for proposals (RFP) that was issued by the NYPA Procurement Division. There were three bidders that responded, and the successful bidder (low-bidder) was Leonard Powers, Inc., of New York City. The solar collector specified was manufactured by the German firm Paradigma Energie. Figure 22-21 shows the layout of the solar collectors and piping on the roof. • Average high temperature/low temperature (winter): 43.3°F/30.8°F • Average annual precipitation: 46 in. • Maintenance barn floor area: 360,000 ft2 • Occupancy: 1,200 • Schedule: 24/7 • Water heating requirements: 13,000 gal/week of hot water • Renewable energy features: Solar water heating system using evacuated-tube collectors • Other energy/sustainability features: efficient lighting systems (T-5 lamps, motion sensors)

Individual Case Studies 171 Project Team Building Owner’s Representative Director, Agency-Wide Environmental and Energy Policy New York Metropolitan Transportation Agency Design New York Power Authority Construction Installation Contractor Leonard Powers, Inc. Solar Collector Manufacturer Paradigma Energie (Germany) Linuo Ritter USA, Inc. (Regasol USA) Construction Oversight NYPA Commissioning NYPA, Paradigma Energie, Leonard Powers, Inc. 22.4.2.3 Construction Phase The most significant issue that arose prior to construction was the ability of the solar collectors specified to meet the New York State code for wind loading requirements. NYPA and MTA worked with the manufacturer to ensure that the collector would meet the requirements. Paradigma Energie undertook wind tunnel testing and made design changes to certify compliance. The Figure 22-21. Solar collector array and piping layout. Source: Ke He, NYPA.

172 Renewable Energy Guide for Highway Maintenance Facilities resulting collector designs became an additional offering by the manufacturer. The other issues that arose included the following: • Expansion tank volume. A misunderstanding about the distinction between “acceptance volume” and “vessel volume” resulted in the installation of undersized expansion tanks (initially). This caused a loss of collector loop fluid due to over-pressurization, and caused stagnation to occur. • Swagelok connection. The overtightening of Swagelok-type connectors on the solar collector inlet and outlet caused several to crack, requiring replacement. • Stagnation during commissioning. Due to inadequate purging of air, there was insufficient fluid in the collector loop upon initial start-up. The collectors went into stagnation when their protec- tive vinyl covers were removed during the commissioning process. This prevented completion of the commissioning until after the stagnation period ended. Discussions among the parties—NYPA, the collector manufacturer, and the installation contractor—resolved these issues quickly. All were involved in the commissioning process, with the collector manufacturer’s commissioning engineer leading the acceptance testing. Training of MTA facility staff was provided by the solar collector manufacturer. This phase of the project took approximately 6 months—from November 2009 to April 2010. A major lesson learned was to ensure good written and oral communications of the specifications among the system designer/ specifier, solar collector manufacturer, and installer. Figure 22-22 shows a closer view of the solar collectors and piping. 22.4.3 Results The solar water heating system was monitored using an ISTEC Btu meter capable of storing up to 13 months of data. The performance of the system was compared to estimates produced by two solar screening/evaluation tools: RETScreen (NRCAN) and TSOL (Valentin Software), and they were found to be in good agreement. From June 2010 through May 2011, the solar system displaced approximately 104,000 kWh (67% of the hot water load of 156,000 kWh) of electricity and reduced electric power demand by 217 kW. The avoided greenhouse gas reductions are 80 tons of CO2e. The associated annual energy operating cost savings are estimated to be about $100,000. The savings were due in large measure to the high electric power demand charges ($30/kW) avoided (about $6,500/month). The estimated payback period is 5.6 years (no incentives), or 4.1 years with incentives. The system is working well and the maintenance requirements have been as expected. There have been no undue burdens on facility staff. Figure 22-22. Solar collector array and piping layout. Source: New York Power Authority, 2011. MTA Coney Island Train Yard, Vacuum-Tube Solar Hot Water System Final Report, NYSERDA, Agreement No. 9915, page 11, Figure 11.

Individual Case Studies 173 Figure 22-23 shows the monthly contributions of the system in terms of avoided electricity purchases. 22.4.4 Lessons Learned • Ensure that solar collectors are certified to meet wind load specifications. • Water can be used as a good heat transfer fluid with evacuated-tube solar collector systems in colder climates. Solar Water Heating System Information • Solar collector type: evacuated tube • Solar collector array area: 1,762 ft2 (48 collectors) • Closed-loop system (pressurized) • Heat transfer fluid: water • Freeze protection: recirculation of heated water • Over-temperature (collector stagnation) protection: expansion tank sized to accept boiling water • Storage tank volume: 2,500 gal • Backup heater: steam-fired instantaneous water heater • System cost: $564,905 ($414,905 after NYSERDA incentive) • Annual energy savings: 104,000 kWh (355 MMBtu) • Percent of annual water heating energy met: 67% • Electric power demand reduction: 217 kW • Annual energy operating cost savings: $100,000 Economics: • 5.6-year payback period (no incentives) • 4.1-year payback period (with incentives) • Applicability: all buildings that have hot water requirements, especially if higher temperature water is needed Source: Ke He, NYPA. 0 2,000 4,000 6,000 8,000 10,000 12,000 Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May El ec tr ic ity A vo id ed (k W h) Figure 22-23. Avoided electricity purchases from solar water heating system contribution June 2010 through May 2011.

174 Renewable Energy Guide for Highway Maintenance Facilities • Make sure there is a common understanding of “acceptance volume” versus “vessel volume” to ensure that the properly sized expansion tank is installed. • Make sure that the installation contractor follows the recommendations for installing the quick-connect –type fittings versus more traditional fittings to avoid damage to the connectors. • Make sure that the primary collector loop is fully charged with fluid and purged of air prior to exposing collectors to sunlight during initial start-up. 22.4.5 Future Plans MTA is implementing similar projects on some of its other transit/transportation facilities: • A 661-ft2 solar collector array (18 panels) system at the Pelham train yard. This was commis- sioned in March 2012. This is a drain-back system, where the water is automatically drained during periods of freezing or stagnation. • A system at the Jamaica train yard is being evaluated. 22.5 Case Study: Denver, CO, Public Works Central Platte Campus 22.5.1 Overview To accommodate the right-of-way for a new light rail line, the City and County of Denver, CO, needed to relocate an existing public works facility to a new site. The new Central Platte Campus is located on a property adjacent to the Platte River with visibility from a major interstate highway. The activities to be accommodated included routine vehicle maintenance for the city’s vehicle fleet, sand and salt storage, automatic vehicle wash and chassis wash, engine repair, and supporting office space for street maintenance, fleet maintenance, solid waste, traffic, and right-of- way enforcement. The campus has six structures totaling 105,000 ft2, including a fleet maintenance facility of 39,546 ft2, enclosed heated storage of 13,493 ft2, office and warehouse of 29,056 ft2, a 6,640-ft2 wash bay, 15,676 ft2 of salt storage, and 7,200 ft2 of covered storage. The completed campus was turned over to the city for occupancy on October 1, 2010. Total construction cost was $25,000,000. The campus supports a fleet of 500 vehicles. Construction of the various structures included tilt-up concrete panels for the fleet maintenance, office/warehouse, and vehicle wash; pre-engineered steel structures for covered vehicle storage and heated vehicle storage; and a pre- engineered wood dome structure for salt storage. The 33-acre site is a remediated brownfield. The site was used for a variety of industrial processes from the 1880s until 2008. These activities included mineral processing and chemical manufac- turing. Located approximately 4 miles from downtown Denver, the site is adjacent to the Platte River and the city’s Art Deco-style wastewater treatment plant and is visible from Interstate 25. The buildings are oriented with the long dimension running north–south to allow the vehicle bay doors to face east and west. This orientation was selected to allow solar access to the east and west sides of the buildings to prevent the build-up of ice and snow that would likely occur if half the bays faced the north. Both the fleet maintenance building and the office warehouse building achieved the LEED Version 2.2 Gold certification requirements. A variety of LEED-compliant sustainability strategies, including the 101.66-kW solar photovoltaic system, were incorporated to achieve the LEED rating. Renewable Energy: The project includes a 102-kW photovoltaic solar energy array that was funded through a PPA. The array is integrated into the sawtooth roof design. The PV system is producing in excess of the pre-construction projections—153,506 kWh annually. In addition to the solar array, the building includes an extensive daylighting system interconnected to artificial lighting systems.

Individual Case Studies 175 Other Sustainable and Energy Efficiency Strategies: To meet LEED requirements, the design of the building envelope and systems reduces energy consumption significantly as compared to a standard building. The maintenance garage is heated by a radiant floor heating system in combination with a tempered air ventilation system. Evaporative cooling, high-efficiency water heating and energy recovery systems are also incorporated. Energy-efficient lighting and task lighting are integrated into the daylighting system. Storm water detention and pretreating is provided, as are low-flow plumbing fixtures and materials and finishes with recycled content. Figures 22-24 through 22-26 show various aspects of the buildings, including the photovoltaic systems. Source: RNL Design, architect. Figure 22-24. Central Platte Public Works Facility—initial rendering of entire campus (with PV at all buildings), operations building in foreground and vehicle maintenance building in far background. Figure 22-25. Vehicle maintenance building showing PV and shading strategies at doors.

176 Renewable Energy Guide for Highway Maintenance Facilities Source: RNL Design, architect. Figure 22-26. Central Platte Public Works Facility — operations center entry facade. Site and Building Information: Location: Denver, Colorado • Address: 1271 West Bayaud Avenue, Denver, CO 80223 • ASHRAE climate zone: 5B • Annual heating degree days (65°F base): 6,020 • Average high temperature (summer): 90°F • Average low temperature (winter): 15°F • Average annual precipitation: 15.81 in. • Facility floor area: 105,000 ft2 • Occupancy: 192 • Schedule: 6 a.m. to 6 p.m. office warehouse; 5 a.m. to 9 p.m. fleet maintenance Renewable Energy Features: • Solar photovoltaic system, net metered (100 kW) • Daylighting • Integrated design for PV and daylighting oriented for optimum solar efficiency Other Energy Efficiency Features: • Efficient lighting systems (T-5 and T-8 lamps, motion + occupancy sensors integrated into daylighting design, task lighting, portable shop task lighting) • Building automation system • Building envelope and systems designed to reduce energy consumption • Hydronic radiant floor heating in combination with variable air volume tempered ventilation system • Non-mechanical (indirect/direct evaporative) cooling system with variable air volume • High-efficiency condensing boiler plant • Ventilation system complies with ASHRAE Standard 62.1. • Ducted general exhaust with energy recovery on major exhaust air systems • Occupancy sensor controlled HVAC terminals • CO2 sensors interconnected with ERVs at high-density occupied spaces • Dedicated vehicle exhaust system at maintenance bays

Individual Case Studies 177 22.5.2 Project Development Process 22.5.2.1 Pre-Design (Project Planning) Phase The project was necessitated by the right-of-way location of the regional light rail system. The need to relocate the city’s vehicle maintenance and other operations resulted in the development of the Central Platte Campus. Construction completion and occupancy occurred in October of 2010. Denver was planning a citywide solar energy project on the heels of successful installations at the Denver International Airport, Colorado Convention Center, and Denver Museum of Nature and Science. The timing of the PPA coincided with the design and construction of the Central Platte Campus and supported the project’s sustainability goals. The Central Platte solar installation is intended to reduce utility costs, reduce environmental impact, support LEED certification, and serve as a visible reminder of Denver’s commitment to renewable energy due to the prominent location of the campus. The project was financed through a PPA as part of a public–private partnership. A third-party solar developer designed, built, operates, and maintains the system, and the city purchases each kilowatt-hour generated by the system over 20 years. The project took advantage of an up-front rebate ($2.00 per watt, capped at $200,000), a per kilowatt-hour performance-based payment from the local utility to account for the renewable energy credits ($0.10/kWh constant price for solar renewable energy credits or SRECs set for 20-year period), and federal incentives, including the investment tax credit and accelerated depreciation schedule. In addition, because the project was located within a qualified distressed census tract, it qualified for new markets tax credits. These incentives were accepted by the solar developer and passed through to the city in the form of a price per kilowatt-hour below that of electricity off the grid. The project was only cost-effective due to these incentives. Colorado’s RPS was the one policy that helped the project the most, and it was also helped by the extension of the investment tax credit through 2016. The city worked closely with the utility, Xcel Energy, to secure incentives through the Solar*Rewards program, to allow those incentives to be provided directly to the developer, and on system interconnection. All systems in Colorado need to be interconnected and net metered to allow electricity produced to be fed to the grid if the system is producing more energy than the building is using, and to offset consumption at other times. The city hopes the 102-kW system will also serve to reduce peak demand charges over time. In addition to the architects and engineers, the design team included a LEED consultant who also provided energy modeling and daylighting design, a civil engineer and landscape architect to design site-related elements for the LEED certification, a programming and equipment consultant to ensure the efficient organization of the facility, and a commissioning agent to verify the operation of the building systems. The project delivery method was a design–build competition with a fixed budget. The process was intended to provide a best-value design solution. The competition was based on an RFP that included the city’s design criteria. Three teams were shortlisted for the main competition phase, Sustainability Features: • LEED Gold rating (V 2.2) at fleet maintenance building and office/warehouse building • Facility fully commissioned • On-site pretreatment of storm water using a detention pond • Low-flow and water-efficient plumbing fixtures used throughout the buildings • Materials and finishes with recycled content

178 Renewable Energy Guide for Highway Maintenance Facilities and selection was by a panel consisting of city officials and end users from each department that was to reside at the site. During the competition phase, progress meetings were held with the city and user groups to provide feedback on the design solution. The project team consisted of the architectural design team in conjunction with mechanical, electrical, plumbing, structural and civil engineers, and equipment and sustainability consultants. The team worked closely with the general contractor and mechanical, electrical, and plumbing contractors to maintain a fixed budget. During the competition, the design team was allowed approximately 3 months to complete the design and establish the construction cost. The structure of the delivery approach allowed for flexibility in design and provided an opportunity for a unique design solution. 22.5.2.2 Design Phase: Renewable Energy System The project was originally designed to include three 100-kW photovoltaic solar energy arrays on three separate buildings. Three of the main buildings were designed to accommodate a roof- mounted PV array. The arrays were to be integrated into the sawtooth roof designs, with the solar array oriented to the south and the daylighting system oriented to the north. This configuration placed the PV array at the optimum solar orientation. However, during the course of the project, Xcel Energy revised their incentive program to limit installations to one PV system per contiguous site. Thus, two of the 100-kW arrays were dropped from the project. The building envelope, mechanical systems, and lighting systems were optimized to perform significantly better than ASHRAE 90.1-2004. Energy design was modeled as required by the LEED rating system and, along with other LEED requirements, resulted in the fleet maintenance building and the office/warehouse building achieving a LEED Gold certification. A lesson learned during the design phase was that plan examiners will bump wind loads/snow loads for untested technology. Solar installations are held to a higher standard. This project was asked to meet higher than required wind loading. Figures 22-27 and 22-28 provide comparative views of the impact of daylighting on the main- tenance area looking away from the light monitors versus looking toward the light monitors. The lighting system includes automated controls. Figures 22-29 through 22-31 show the photovoltaic array and close-ups of the mounting structure. Figure 22-27. Daylighting looking away from light monitors.

Individual Case Studies 179 Figure 22-28. Daylighting looking toward light monitors. Figure 22-29. Central Platte Public Works Facility—solar PV array. Source: Main Street Power. Figure 22-31. Penetrating mounting—standing seam metal roof installation. Figure 22-30. Ballast mounting—single-ply roofing installation.

180 Renewable Energy Guide for Highway Maintenance Facilities 22.5.3 Results Project Team Building Owner’s Representative City and County of Denver Public Works Division Engineering Specialist—Major Projects Office Public Works, Capital Projects Management Architect RNL Design Consultants Maintenance Design Group: equipment Ambient Energy: LEED, energy and daylight modeling MKK Consulting Engineers: mechanical, electrical, and plumbing engineering (MEP) engineering Construction Pinkard Construction, general contractor Duro Electric, electrical contractor AMI Mechanical, mechanical and plumbing contractor Millander-White, PV system installer Encore Energy Services, electrical subcontractor for PV PV System 101.66-kW DC system installed at multiple tilt angles 442 module 230-watt panels, Canadian Solar CS6P230 39.6 kW installed at 10.5-degree tilt 62.1 kW, installed at 18.43-degree tilt 0.82 DC-to-AC derate factor System became operational on March 7, 2011. PPA Provider Main Street Power Commissioning Agent Architectural Energy Corporation 22.5.3.1 Construction Phase—Renewable Energy System Since this was a design–build project, the design team worked directly with the construction team for the entire project. However, the installation of the PV array, which was provided through the PPA between the city and Main Street Power, commenced after the building was substantially complete. Even though the installer coordinated roof connections with the design–build team, there were still issues with roofing warranty and roof connections. Additionally, after bidding, the roof underwent value engineering. This resulted in a change to the PV mounting system, which introduced some coordination issues. Some lessons learned during the design phase are: • Roofer must do all the penetrations of roof membrane in order to maintain the warranty. • Confirm required wind loads/snow loads for solar installations. • Roof-mounted PV systems require thorough coordination between roofer, PV installer, and electrical contractors. • PPA process: Developer buys equipment; general contractor installs; power purchase pro- vider owns, operates, and maintains—thus, there is an issue of coordination between the developer and installer. It was recommended that the construction team be in charge of this coordination. 22.5.4 Results The PV system includes panels deployed on the facility roof at two different angles: 10.5 degrees and 18.43 degrees. The production for each installation angle was modeled, and expected pro- duction as well as design electric consumption was predicted as indicated in the Table 22-3.

Individual Case Studies 181 The system became operational in March of 2011. During the initial 10 months of operation, the PV system produced in excess of the pre-construction projections: 153,506 kWh annually. Overall, the results of the renewable energy installation are meeting the expectations of the owner. The sys- tem has been economically beneficial since it was commissioned. The price paid per kilowatt-hour of electricity from the PPA, $0.0293/kWh, is $0.039/kWh below the cost of electricity from the utility. This represents an annual savings of $5,986.00. If the price of electricity continues to escalate faster than the contract price of the solar-produced power, the system will continue to save the city addi- tional money. It is estimated that the savings over the 20-year life of the PPA will be approximately $200,000 when utility rate increases are factored in. The system is operated and maintained by the solar developer (power purchase provider), per the terms of the contract. The city’s General Services Department and Sustainability Office monitor the system’s costs and benefits, but all maintenance costs are borne by the power purchase provider. The system is monitored by a production meter (that tracks production and quantifies production of the system’s renewable energy credits) and a monitoring software package. Performance can be viewed via a website that shows real-time generation of the system. This information is avail- able to the owner and the public. Tracking the performance allows the developer to learn as soon as possible if the system is not producing up to its specified capacity. The system uses NREL’s virtual weather station and monitors production of the array only. Performance can be viewed at http://www.alsoenergy.com/powertrack/lobbyview.aspx?sid=84. Figure 22-32 shows the system output from March 2011 through December 2012. 10.5-Degree Tilt 18.43-Degree Tilt Installed power (DC) kW 39.6 Installed power (DC) kW 62.1 DC-to-AC derate factor 0.82 DC-to-AC derate factor 0.82 Array type Fixed tilt Array type Fixed tilt Array tilt 10.5 Array tilt 18.43 Estimated generation kWh 55,850 Estimated generation kWh 92,151 Total Generation kWh: 148,001 kWh Total design electric consumption kWh: (Does not include 756 MMBtu of natural gas.) 213,322 kWh Table 22-3. Design specifications for PV system. Figure 22-32. Solar energy production.

182 Renewable Energy Guide for Highway Maintenance Facilities Bills for service are monitored and reconciled monthly by the city’s General Services Department. To date there have been no operational issues with the renewable energy system. 22.5.4.1 Building Energy Performance As part of the certification process for LEED, the building energy performance was also modeled by the design team. Table 22-4 shows the modeled performance of the building to be 33% below the baseline design. The reduced building loads allow the energy produced by the PV system to be a larger percentage of the overall building demand. 22.5.5 Lessons Learned • The PPA covers all system operations. This benefits an entity like the City of Denver that has no expertise in the operation and maintenance of a solar PV system. • Additionally, the PPA is being paid based on system production, so they have an incentive to keep the system operating at peak performance. • The PPA allows public entities to obtain some of the benefits and incentives available to the private sector. 22.6 Case Study: South Bend, IN, Public Transportation Organization Maintenance Facility 22.6.1 Overview South Bend Public Transportation Organization (TRANSPO) is municipally owned by the City of South Bend, IN. It is the nucleus of transit services for the South Bend and Mishiwaka communities. All administration, operations, vehicle maintenance, and storage are housed under one roof in their newly constructed facility of 167,000 ft2, which was completed in November of 2010. The facility is sized to house and maintain 76 vehicles and is constructed primarily of steel-framed and load-bearing steel stud con- struction with masonry and prefinished metal panel exterior finishes and polycarbon ate glazing. The facility currently operates 20 hours per day (4:00 am–midnight) year round with 115 employees. Thirty-five of the employees are housed in the building, while 80 are drivers who are in the building at various times during their shifts. The project was partially funded by the federal government (20%), with the remaining (80%) being local funds. Additionally, two grants were obtained from the FTA and ARRA to help fund the facility. The 20-acre site is a remediated brownfield and formerly housed the Studebaker automobile fac- tory. The facility is the first development in the master plan for Ignition Park, which will be a future home for light industry in South Bend. The building is oriented along the east–west axis to maximize solar gain, create great daylighting opportunities within the building, and create south-facing traffic flow and access into the building. The architecture team pushed renewable energy and achieving a Proposed Design Baseline Design Savings Energy Type Energy Use (kBtu/year) Cost Energy Use Cost Energy Use Cost Electricity 728,068 $21,890 1,049,598 $32,558 30.6% 32.8% Natural Gas 755,934 $6,829 1,166,693 $10,395 35.2% 34.3% Total $28,719 $42,953 33.1% Total (Model Outputs) 1,483,895 2,216,290 33.0% Table 22-4. Predicted building energy performance.

Individual Case Studies 183 LEED Platinum rating from the project’s beginning. The client was interested in obtaining a LEED certification but when told a LEED Platinum rating was attainable, they embraced pursuing the highest LEED rating. The project incorporated efficient function and best practices to develop an energy-efficient and economical building that uses a variety of strategies to reduce energy consump- tion and meet sustainable building goals. Renewable Energy: The project includes a 93.5-kW thin-film PV solar energy system installed on the south-facing portion of the bus storage roof. With an initial cost of $600,000, the system is estimated to generate 7% of the facility’s electricity—about 97,259 kWh annually. This equates to a savings of $5,474 in electricity bills. A ground-source (geothermal) heat pump system incorporating 48 wells, each 300-ft deep, provides space conditioning for office areas, housing maintenance, administration, and operations. The ground-source heat pump is estimated to save 38,429 kWh, or $2,152. Extensive daylighting is provided throughout the facility. Artificial lighting systems are connected to motion and occupancy sensor systems. The fixtures are auto- matically shut down or dimmed depending on the presence of workers and the total amount of daylight detected in each zone. In addition, TRANSPO has purchased RECs equal to about 35% of the total electricity use of the facility. Other Sustainable and Energy Efficiency Strategies: The project was designed to meet the 2030 Challenge, a nationally adopted initiative by the American Institute of Architects to reduce and eventually eliminate CO2 emissions by buildings by the year 2030. All areas of the building are conditioned. However, the largest area, bus storage, is only heated to approximately 50°F during the heating season, or to a level to ensure that ice and snow buildup is melted off the vehicles while stored. The design of the building envelope and systems reduces energy cost by 39.8% and consumption by 54.1% as compared to ASHRAE Standard 90.1-2004 and has an EUI of 46.4 kBtu/ft2/year. The maintenance garage is heated by a radiant heat system connected to both gas and electric boilers. The electric boiler is used during off-peak hours at a negotiated rate. Exhaust systems in bus storage and the maintenance garage are ducted. The facility is controlled by a Honeywell WEB-AX Building Automation System. All storm water is retained on-site and is filtered through bioswales, which use plants to naturally filter out all particulates and toxins that are typical from parking lot runoff. The storm water conveyance design re-establishes wetlands and native habitat. Figures 22-33 and 22-34 show an elevation view of the facility and a view of the roof-integrated thin-film photovoltaic system, respectively. Source: Merlin Maley, RNL Design. Figure 22-33. TRANSPO maintenance facility.

184 Renewable Energy Guide for Highway Maintenance Facilities Source: Merlin Maley, RNL Design. Figure 22-34. TRANSPO roof-integrated thin-film photovoltaic system. Site and Building Information: Location: South Bend, Indiana • Address: 1401 South Lafayette Boulevard, South Bend, IN 46612 • ASHRAE climate zone: 5A • Annual heating degree days (65°F base): 6,294 (South Bend Regional Airport) • Average high temperature (summer): 72.9°F • Average high temperature/low temperature (winter): 30.4°F/23.3°F • Average Annual Precipitation: 39.7 in. • Facility floor area: 167,000 ft2 • Occupancy: 115 • Schedule: 20/6 Renewable Energy Features: • Solar photovoltaic system, net metered (93.5 kW) • Daylighting • Ground-source (geothermal) heat pumps (48 wells, each 300-ft deep) Other Energy Efficiency Features: • Efficient lighting systems (T-5 and T-8 lamps, motion and occupancy sensors integrated into daylighting design, task lighting, portable shop task lighting) • Building automation system (Honeywell WEB-AX) • Building envelope and systems designed to reduce energy consumption by 54.1% compared to ASHRAE Standard 90.1-2004 (energy use intensity of 46.4 kBtu/ft2/year) • Gas/electric boilers allow off-peak electric use to heat radiant slab at maintenance. • Ducted exhaust systems Sustainability Features: • LEED Platinum rating (first LEED Platinum-certified maintenance/admin/operations facility in the United States) • Meets 2030 Challenge criteria (CO2 reduction) • Facility fully commissioned • Building flush-out prior to occupancy • On-site treatment and discharge of storm water using bioswales.

Individual Case Studies 185 22.6.2 Project Development Process 22.6.2.1 Pre-Design (Project Planning) Phase The project consolidates all administration, operations, maintenance, and storage for TRANSPO on one site and under one roof. The conceptual design for the project began in June of 2007, with construction completion and occupancy in November of 2010. TRANSPO was interested in a LEED- rated building. The architect pushed for the highest LEED rating attainable (Platinum) and assem- bled a team that found the project and site could meet the requirements for LEED Platinum. The requirements of the 2030 Challenge were also identified as possible for the project. In addition to the architects and engineers, the design team included a LEED consultant who also provided energy modeling and daylighting design, a civil engineer/landscape architect to design site-related elements for the LEED certification, a programming and equipment consultant to ensure the efficient orga- nization of the facility, and a commissioning agent to verify the operation of the building systems. TRANSPO recognized that transit service providers’ duty is to spend money on improving and increasing transit service in their communities. Every dollar saved in operational expense for their facility can then be used to provide better services. To meet this objective required the proposed building to be extremely energy efficient and economical to operate. The design team identified various strategies to meet TRANSPO’s need for low operating costs and meet the requirements of the LEED rating system and the 2030 Challenge. Grant funds from ARRA, the FTA (FTA-Section 5307-Urbanized Areas and FTA-Section 5309- Capital Investment), and an FTA Transit Investment for Greenhouse Gas and Energy Reduction (TIGGER) grant were used for the building and the renewable energy system. Support from these programs was instrumental in achieving the facility that was eventually constructed. Fundraising for the building began in 2002. The project delivery method was the traditional design–bid–build approach. Increased reporting and documentation was required due to the FTA and ARRA grant processes and LEED-certification process guidelines. The key lesson learned during the pre-design phase was that having a general contractor or construction manager hired as a team member early in the process would have been extremely valuable. This team member could have provided insight and knowledge in best construction practices and scheduling to help reduce the over- all cost of the project. 22.6.2.2 Design Phase The architectural design team was selected through a competitive request for qualifications process. Many of the design decisions were based on the stated pre-design objectives of having a sustainable, energy-efficient building with low operating and maintenance costs. Strategies that were incorporated include: • The building envelope, mechanical systems, and lighting systems were optimized to perform significantly better than ASHRAE 90.1-2004. Energy design modeling indicated an energy use reduction of 54.1% from the standard and an EUI of 46.4 kBtu/ft2/year. These design activi- ties were essential to achieving the LEED Platinum rating and meeting the requirements of the 2030 Challenge. • Incorporation of a grid-tied, thin-film, roof-mounted photovoltaic solar array reduces the building’s annual utility cost by approximately 4.9%. The photovoltaic array was not included in the initial design due to budget restrictions, but was added to the project after obtaining the TIGGER grant. • Areas of the facility that are both heated and cooled have ground-source heat pumps that more efficiently use electricity for space conditioning than other electric-based types of systems. The system includes 48 wells that are 300-ft deep, providing heating and cooling for the administration and operation portions of the facility.

186 Renewable Energy Guide for Highway Maintenance Facilities • Coordination with the local utilities led to inclusion of both electric and gas-fired boilers to allow the system to take advantage of reduced off-peak electric rates while using lower cost (per Btu) gas to fire the boilers during the day. • Radiant slab heating provides a flywheel effect to carry the off-peak purchased electrical heat into the on-peak portion of the day. The radiant slab heating system is in the vehicle maintenance portion of the facility. • Exhaust systems are ducted. • Building automation provides efficient operation of the systems. Honeywell WEB-AX equipment was installed. • Use of dimmable, energy-efficient lighting, motion sensors, occupancy sensors, a building- integrated daylighting system, daylight sensors/controls, and task lighting reduce electrical consumption for lighting. • Use of building commissioning at the completion of construction to verify systems are per- forming to design specification. Project Team Building Owner’s Representative TRANSPO Maintenance Manager Architect of Record Forum Architects Design Architects RNL Design Consultants Maintenance Design Group: programming Ambient Energy: LEED, energy and daylight modeling M/E Design Services: MEP engineering Keller Engineering: structural engineering Construction General Contractor Robert Henry Corporation Commissioning Agent Primera 22.6.2.3 Construction Phase Project delivery was by the traditional design–bid–build process. The renewable energy sys- tem was bid as part of the general construction contract, and the selected bidder entered into an agreement with the PV installer. Daylighting, as part of the architecture of the building, was included under the general contract, with controls provided by the electrical contractor. Com- missioning was done by a third party contracted by the owner and selected based on their experience and relatively close location to the project site. A major lesson learned from the construction process was that close coordination and scheduling between the subcontractors is needed to avoid sequenc- ing issues. In some instances, completed work had to be removed and then redone. In addition, more attention to testing and balancing requirements of the HVAC system would have been helpful. Figure 22-35 shows the photovoltaic system electrical connections. Figures 22-36 and 22-37 illustrate the ground-source heat pump system. Figure 22-38 highlights daylighting applications in the building. 22.6.3 Results TRANSPO’s new building is twice the size of their previous facility, and to date the utility costs are the same. The solar PV system is operational and has been producing power since

Individual Case Studies 187 commissioning. It is estimated to provide 7% of the electricity of the facility, or 97,259 kWh annually. This equates to a savings of $5,474 in electricity bills. The ground-source heat pump is estimated to save 38,429 kWh or $2,152 annually. Extensive daylighting is provided throughout the facility. In addition to lowered utility costs, the new facility is designed to increase operational and maintenance-related efficiencies. The design team concentrated on the organization and layout to create a safe and efficient vehicle circulation pattern and to meet or exceed TRANSPO’s functional requirements. Improved indoor air quality has resulted in happier and healthier Source: Merlin Maley, RNL Design. Figure 22-35. Close-up of roof-integrated thin-film photovoltaic system showing electrical connections. Source: Merlin Maley, RNL Design. Figure 22-36. Construction of ground-source (geothermal) heat pump wells.

188 Renewable Energy Guide for Highway Maintenance Facilities employees and reduced absenteeism. Occupants are very happy with the bright ambient daylight throughout the building. 22.6.4 Lessons Learned TRANSPO is using measurement and verification (part of the LEED-certification process) as a tool to track energy performance. They are also using the facility to educate about sustainability and their mission. The two goals of education and performance are related. However, the ability Source: Merlin Maley, RNL Design. Figure 22-37. Ground-source heat pump distribution header. Source: Merlin Maley, RNL Design. Figure 22-38. Daylighting of representative spaces—part of integrated lighting solution.

Individual Case Studies 189 to tell the energy story in real-time was not identified as a goal until after construction had begun. Identifying this up-front would have allowed the relatively small investment in infrastructure required to provide real-time performance to be included in the budget. 22.7 Case Study: Caltrans Clean Renewable Energy Bonds Program, Sunrise Maintenance Facility Photovoltaic System 22.7.1 Overview Caltrans has undertaken the installation of PV systems at 70 of its facilities through- out the state. This was made possible through the use of the U.S. Internal Revenue Ser- vice (IRS) CREBs program to help finance the projects. A major driver for Caltrans was to help meet energy objectives for state buildings that called for a 20% reduction in grid- purchased electricity by 2015.99 Of the 70 facilities, 46 are designated as maintenance-related. The photovoltaic systems range in capacity from 3 kW to 165 kW (CEC-AC rating) and total about 2.4 MW (CEC-AC rating). The Sunrise Maintenance Station photovoltaic sys- tem located in Rancho Cordova in Sacramento County is a representative Caltrans CREBs PV project that was installed in 2010. The station, which was constructed in 2001, consists of four buildings totaling 24,000 ft2 and supports road maintenance operations and electri- cal crews that repair signals and signs. The buildings are of metal construction and meet California energy code (Title 24) requirements. The maintenance bay areas of the main- tenance and repair bay building are heated with gas-fired unit heaters or radiant heaters, while the office areas are both heated and cooled. The electrical loads are for lighting and HVAC, with some intermittent loads for the fuel island and air compressors. The station is occupied 10 hours per day and has a staff of 30 people, most of which are in the field during the day. A 30-kW (CEC-AC rating/35.6 kW DC STC rating) PV system was installed on an existing 4,130-ft2 material storage building roof canopy to serve the station. The PV system consists of 192 Canadian Solar brand panels (180 watts DC-rated output each) of crystalline silicon cells that are mounted at a slight tilt on the standing seam metal roof. The 2,638-ft2 PV array is tied into the distribution network and has net metering. The performance is monitored by a separate meter that can be remotely accessed via the Internet. The system generated about 46,546 kWh of electricity during its first full year of operation (June 2010–May 2011) and saved an estimated $6,703 in utility bills. The system cost $193,402, or $6,447/kW (CEC-AC rating) or $5,590/kW (DC rating). This was partially offset by a $40,000 incentive from the Sacramento Municipal Utility District (SMUD), the utility provider. This incentive was given directly to the state to help accelerate the payments on the bond. The economics and savings equate to a 23-year payback period with incentives (27 years without), not including CREBs design and administrative costs. The system has worked well, although there was a problem with the inverters that reduced the output during the summer of 2011. Overall, there has been satisfaction with the system at Sunrise, as well as at the other sites, and Caltrans plans to continue to look for opportunities to incorporate PV systems into its facilities (e.g., as part of LEED for new construction). Figures 22-39 and 22-40 show the photovoltaic system on the storage canopy. 99Caltrans, 2011. Clean Renewable Energy Bond Program 2011 Annual Report, p. 2.

190 Renewable Energy Guide for Highway Maintenance Facilities Source: Alan Torres, Caltrans. Figure 22-39. A 30-kW photovoltaic system at Sunrise Maintenance Station installed on material storage canopy. Source: Alan Torres, Caltrans. Figure 22-40. Close-up of PV array. Site and Building Information: Rancho Cordova, California • Address: 11325 Sanders Drive, Rancho Cordova, CA 95742 • ASHRAE climate zone: 3B • Annual heating degree days (65°F base): 2,229 • Average high temperature/low temperature (summer): 91°F/58.5°F • Average high temperature/low temperature (winter): 59.5°F/43.4°F • Average annual precipitation: 19.9 in. • Building floor area: 4,000 ft2 • Occupancy: 30 (typically 5 to 6 on-site during the day, the remainder in the field) • Schedule: 10 h/day • Renewable energy features: 30-kW (CEC-AC)/35.6-kW (DC) photovoltaic system

Individual Case Studies 191 22.7.2 Project Development Process 22.7.2.1 Pre-Design (Project Planning) Phase The CREBs program was established by the federal government under the Energy Policy Act of 2005. It was designed to help promote green power projects by state and local public entities by allowing them to issue tax credit bonds. These bonds bear no interest; however, they allow the bondholder to take credits against their federal taxes. The credits are based on rates that are set daily by the Treasury Department and are a function of the term of the bond. Public entities that issue the bonds benefit because they only have to pay the princi- pal and not the interest portion of the bond note. The CREBs program is no longer taking applications. In 2006, Caltrans applied for CREBs program support for 94 Caltrans photovoltaic proj- ects. Ninety-three of these projects were approved, at an estimated cost of $45.6 million.100 Subsequent to the CREBs award, the number of projects was reduced to 70, with a budget of $19.9 million, based on better information and screening of the initial sites. The projects were selected based on a general site screening that included considerations of building roof area, shading, condition, expected life (roof and building), electricity use, utility rates, utility incentives, and regulations. The performance of the photovoltaic systems (efficiency) and roof area and electricity requirements was used to size the systems. Based on this informa- tion and the cost of typical systems, the economics (benefit/cost) of the PV installations were determined. The initial calculations indicated that the systems could pay for themselves within the 15-year term of the CREBs. To implement the Caltrans CREBs program, a project team was established from the Caltrans Division of Business Facilities and security and district staff. A design–bid–build approach was used with Caltrans headquarters staff responsible for the design requirements, performance specifications, generating the design, developing the procurement documents, and providing overall project management and oversight. Key members of the design team took a specialized course in PV to prepare for the work. The construction management and oversight at the indi- vidual project level were assigned to regional staff from a group within the construction division. The design team staff was responsible for the final inspections, including performance verification. It was decided that the systems for each site should be bid individually, rather than bundled into fewer larger procurements. This was done to encourage participation by more firms and to help generate more work for local economies. The Sunrise Maintenance Station photovoltaic project was developed using this process. Key factors in selecting the Sunrise facility were easy access to the clear roof, no major changes required to the structure or electrical connection requirements (e.g., new electric service panels), the availability of rebates from SMUD, and the relatively high price of electricity ($0.144/kWh). A major lesson learned during the planning process was to make sure to work with the utility before undertaking PV projects. It is important to understand the implications of installing a photovoltaic system on the choice of electric service tariffs. The utility may require that customers with PV systems switch to a special PV or on-site generator type tariff. Such tariffs often include additional charges for such things as standby power, which are not in standard tariffs. In any case, a careful determination of what the utility costs will be under the existing tariff or special tariff should be made. The facility should work with the utility account representative to understand the tariff options and their cost impacts. 100Caltrans, 2011. Clean Renewable Energy Bond Program 2011 Annual Report, p. 2.

192 Renewable Energy Guide for Highway Maintenance Facilities 22.7.2.2 Design Phase The design was based on meeting the system capacity as defined during the planning phase. A performance specification was used as the basis for the competitive procurements. This required all bidders to meet the system capacity, based on the California Solar Initiative (CSI) requirements (CEC-AC module rating). The CSI is a state incentive program to spur the installation of solar technologies. The CEC-AC rating is intended to provide a more realistic assessment of the useful output of the PV panels than either the nameplate DC rating (STC rating) or the PTC rating. It is used under the CSI program as the basis for determining performance-based rebates. It is supposed to provide an estimate of the AC output of PV panels, accounting for losses in convert- ing PV-generated DC power to AC. A key specification developed for this project was inverter performance requirements (voltage output) under extreme conditions (e.g., very hot days and cold, sunny days). This was done to ensure that the inverter would be able to continue to operate under a broad range of conditions. The specification also included requirements for performance monitoring of the system. Any special requirements pertaining to site conditions were identified when possible. The winners were selected on the basis of the lowest bid that could meet the requirements. In order to expedite design reviews by the fire marshal, a streamlined process was established. Plans for three representative projects were reviewed, with changes made to comply with photo- voltaic system guidelines developed by the fire marshal’s office. Each of the 70 projects, including Sunrise, was still reviewed, but the review time was reduced from 4 to 6 weeks per project to as little as a day. In the case of Sunrise, the specification requiring that no more than 100 ft2 of roof area be disturbed by the installation of the system was waived. This is because the roofing was metal and the structure and its contents did not pose a fire hazard. A major lesson learned was to plan for regulatory reviews early in the design process. Another lesson learned was that the CEC-AC rating was limited in its effectiveness. While the rating does take into account inverter losses, it does not include other factors such as dirt and wire losses. A better way would be to specify the DC nameplate data and use a site-specific performance adjustment (derate) factor to estimate the system output. Project Team Building Owner’s Representative CREBs Project Manager California Department of Transportation Design Division of Engineering Services California Department of Transportation Chief, Office of Electrical and Mechanical Water and Wastewater California Department of Transportation CREBs Program Manager/Lead Engineer California Department of Transportation Senior Electrical Engineer California Department of Transportation Transportation Engineer California Department of Transportation Construction General Contractor Wenham Construction Solar PV Panel Manufacturer Canadian Solar • Model CF5a-180M (180W DC) Construction Oversight California Department of Transportation Division of Construction Commissioning California Department of Transportation Division of Engineering Services

Individual Case Studies 193 22.7.2.3 Construction Phase The PV construction contract was awarded to the firm that could meet the specification for the lowest price. For Sunrise, the installation of the PV system was performed by Wenham Construction. There were no construction issues encountered, and the installation followed the design specifications. Figures 22-41 through 22-44 show the maintenance station and repair building, as well as the materials storage building before and after installation of the roof-mounted photovoltaic array. 22.7.3 Results All the Caltrans systems are being monitored to determine the annual electricity generated and the avoided cost of utility-generated power. The photovoltaic system at Sunrise has a separate meter that records the electricity generated at 15-min. intervals, which can be remotely accessed via the Internet. The system generated 46,546 kWh of electricity during its first full year of Source: Alan Torres, Caltrans. Figure 22-41. Sunrise Maintenance Station— maintenance and repair bay building. Source: Alan Torres, Caltrans. Figure 22-42. Sunrise Maintenance Station materials storage building prior to photovoltaic system installation.

194 Renewable Energy Guide for Highway Maintenance Facilities operation (June 2010–May 2011) and saved an estimated $6,703 in utility bills. The system cost $193,402, or $6,447/kW (CEC-AC rating) or $5,590/kW (DC rating). This was partially offset by a $40,000 incentive from SMUD, the utility provider. This incentive was given directly to the state to help accelerate the payments on the bond. The economics and savings equate to a 23-year pay- back period with incentives (27 years without), not including CREBs design and administrative costs. The system has worked well, although there was a problem with the inverters that reduced the output for several months during the summer of 2011. Overall, there has been satisfaction with the system at Sunrise as well as at the other sites, and Caltrans plans to continue to look for opportunities to incorporate PV systems into its facilities. Photovoltaic System: • PV system type: polycrystalline silicon, Canadian Solar module model CF5a-180M (180 W DC) • PV system rated capacity: 30 kW (CEC-AC rating)/35.6 kW (DC) Source: Alan Torres, Caltrans. Figure 22-43. Photovoltaic module mounting detail. Source: Alan Torres, Caltrans. Figure 22-44. Electric interface for the photovoltaic system.

Individual Case Studies 195 • PV system area: 2,638 ft2 (192 modules @ 13.4 ft2/module) • System cost: $193,402 (without $40,000 SMUD incentive) • Annual energy displaced: 46,546 kWh • Annual energy operating cost savings: $6,703 • Economics: 23 years (payback period with incentives) and 27 years without incentives • Applicability: All buildings that have adequate roof space, full exposure to sunlight, and no structural issues The performance of the PV system is shown in Figure 22-45. Note that due to problems with the inverter, the there was reduced output in June and August 2011 and no output in July 2011. 22.7.4 Lessons Learned Some general lessons learned across all the CREBs projects include:101 • Larger systems cost less than smaller systems, although the administration costs are the same. The construction costs for systems less than 50 kW are averaging $7 to $8 per watt (CEC-AC rating), while systems between 50 kW and 150 kW are averaging $5 to $6 per watt (CEC-AC rating). • Project support costs for design, project management, oversight, monitoring, and reporting are about 25% of the capital cost. • Buildings that are in environmentally sensitive areas or are historical add significantly more time and cost to photovoltaic system project development. The issues should be identified early in the process and mitigated. • Roof-mounted photovoltaic panels should be tilted at least 10 degrees to enable dirt to wash off. Depending on the location, dirt can significantly reduce the system output. • Specify slightly oversized inverters (about 5% larger) to ensure efficient, reliable operation under a broad range of conditions. Source: Alan Torres, Caltrans. 0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 Ju n Ju l A ug Se p O ct N ov D ec Ja n Fe b M ar A pr M ay Ju n Ju l A ug Se p O ct N ov El ec tr ic ity G en er at ed (k W h) Figure 22-45. Electricity generated by PV system: June 2010 through November 2011. 101Caltrans, 2011. Clean Renewable Energy Bond Program 2011 Annual Report, adapted from Exhibit 4.

196 Renewable Energy Guide for Highway Maintenance Facilities • The costs of performance monitoring, including labor costs associated with data review and evaluation, should be accounted for. • Understand utility rules regarding interconnection and net metering and how they affect utility bills. For example, in net metering situations, PV-generated electricity in excess of the facility’s annual requirements will generally not be compensated by the utility. Install- ing a PV system may result in a different tariff and rate structure, which could affect sav- ings. When sizing systems, it is important to understand both current and projected usage (load growth or reduction). • Ensure that design teams benefit from the learning curve when doing multiple systems. Com- munication and information transfer via the Internet can be very helpful. 22.7.5 Future Plans • Caltrans planned to complete the remaining PV installations by the end of 2012. • Caltrans plans to continue to look for opportunities to incorporate PV systems into its facilities. Several new buildings are being planned that will use PV systems as a way of meeting LEED requirements. • There are no plans to expand the system at Sunrise at the present time. 22.8 Case Study: Milford, UT, Highway Maintenance Station Wind Turbine 22.8.1 Overview The Milford Maintenance Station, located in Milford, UT, serves as a highway maintenance station for the Utah Department of Transportation (Utah DOT). The main building is a 3,434-ft2, five-bay storage and office facility. The facility operates year round and has a varying number of employees depending on the season; as few as two employees can be present during the con- struction seasons. In April 2006, then-governor John Huntsman Jr. unveiled the “Utah Policy to Advance State Energy Efficiency.” One plank of this policy was increasing renewable energy within the state government. Utah DOT explored locations to site a small wind turbine to become more familiar with the technology, and the Milford Maintenance Station was identified as a site with good wind resources, available land, low power use, and the permitting environment neces- sary to actually implement the project. A U.S. DOE grant was applied for and awarded to cover 50% of the $13,500 installed cost of the 1.8-kW-rated turbine (see Figure 22-46). Utah DOT provided the remaining funding, which was partially offset by the involvement of the Milford maintenance personnel in the construction process. The project was designed in-house and installed in less than a month. The turbine has functioned as expected and without significant maintenance requirements. Not accounting for rate increases, the estimated savings is 3,000 kWh annually, and the turbine has a payback period of 16 years (based on the installed cost after the grant and offset labor). This process was an important first step for the Utah DOT to understand what exactly goes into wind projects and given its success has allowed the Utah DOT to begin exploring larger-scale wind projects. This project highlighted several important lessons learned, including that using on-site maintenance crews to perform the labor can be an effective way to minimize costs, using specialized contractors for portions of the process is vital, and involving key players throughout the process is important. The facility is scheduled to be replaced in the coming years, and the current wind system as well as solar photovoltaic systems and energy efficiency measures will hopefully be integrated into the design of the new facility.

Individual Case Studies 197 22.8.2 Project Development Process 22.8.2.1 Pre-Design (Project Planning) Phase The project was conceived to meet Utah’s goal of increasing the use of renewable energy within government facilities and as an opportunity to become more familiar with the installation and utilization of wind turbines. The feasibility of the project was determined through an analysis of the Milford Municipal Airport’s anemometer data as well as the station’s energy consumption. Source: Tim Ularich, Utah DOT. Figure 22-46. The 1.8-kW wind turbine at the Milford Maintenance Station. Site and Building Information: Location: Milford, Utah • ASHRAE climate zone: 5B • Annual heating degree days (65°F base): 5,765 • Average high temperature/low temperature 77.0°F/15.1°F • Average annual precipitation: 10.16 in. • Maintenance station floor area: 3,434 ft2 • Occupancy: two to five people • Schedule: 6:00 a.m.–4:30 p.m. • Electric energy requirements: 192 kWh/week • Renewable energy feature: 1.8-kW wind turbine

198 Renewable Energy Guide for Highway Maintenance Facilities The airport is approximately 1.5 miles north of the station and has similar topography. It was concluded from data obtained via the local airport that wind levels were sufficiently high to sup- port a turbine: an average of 10.7 mph. Given the levels of wind recorded, it was expected that a small turbine would produce roughly 25% to 35% of the station’s electric energy use, or 3,000 kWh annually. Additionally, the site in Milford offered no major obstacles to permitting, and the city itself was viewed as being very amiable to wind towers. The local utility, Rocky Mountain Power, was not as familiar with renewable energy projects; however, they were open to education about the process. All of these reasons made this facility a good test bed for a wind energy project. In order to fund the project, a U.S. DOE grant was applied for and awarded to cover 50% of the costs of the project. The remaining funding was provided by Utah DOT, with the maintenance personnel at the location playing a central role in the actual construction process to offset a portion of the cost. This project was implemented as a design –build project, with in-house personnel selecting the turbine, and used a state-contracted renewable energy distributor, AEE Solar, to procure the parts. The planning team consisted of central maintenance staff, the local maintenance station supervisor, and senior manage- ment. The whole process—from design and parts order to construction and final inspection—took less than a month. An important lesson learned was that using maintenance crews to assist with the installation is a very cost-effective method to match project grants. 22.8.2.2 Design Phase The design was led by Utah DOT and was closely coordinated with the local maintenance staff at the Milford Maintenance Station and Green Power Solutions, Inc., the electrical contractor. The local maintenance staff was tasked with the heavy labor activities, and the electrical contractor helped erect the turbine and wire the main disconnect and main service panel. The turbine selec- tion process—type and capacity—was driven by the relatively small electrical load and a desire to simplify the installation. The turbine selected was the Skystream 3.7 manufactured by Southwest Windpower, Inc. This small turbine—installed rating of 1.8 kW at the rating condition of 20-mph wind speed—is designed for homes and small business applications. The unit’s controls and inverter are housed inside the turbine, allowing for easier installation. There were no special local codes that applied to the project. The design team decided to use the 2008 NEC as the electrical standard and followed the manufacturer’s recommendations with respect to turbine placement. The turbine was designed on a mono pole such that guy wires would not be an issue with respect to yard space and function. A lesson learned in the design phase was to get all the key players involved early to ensure that everyone knows the objectives and vision of the project. Project Team Building Owner’s Representative Deputy Maintenance Engineer Utah DOT Design Deputy Maintenance Engineer Utah DOT Construction Electrical Contractor Green Power Solutions, Inc. Wind Turbine Supplier AEE Solar Wind Turbine Manufacturer Southwest Windpower, Inc. Construction Oversight Utah DOT Commissioning Utah DOT

Individual Case Studies 199 22.8.2.3 Construction Phase The construction phase of this project was very straightforward. The Utah DOT project lead designed the foundation and selected the turbine location after walking the site with the site foreman. The site foreman supervised the local maintenance staff as they performed the excava- tion, trenching, and concrete pouring, including the wiring and placement of the reinforcement cage for the turbine (see Figure 22-47). The electrical contractor was brought in to assemble the turbine and wire the system. The turbine was inspected by the local utility, which focused on the point of interconnect to the local distribution system. Both the primary designer and the electri- cal contractor had significant experience with renewable energy systems and reviewed the project extensively. A major lesson learned in this phase was that while in-house staff can accomplish significant portions of a project like this, the use of experienced contractors in key areas is critical. 22.8.3 Results The wind turbine generator is monitored and accessed using net metering readings since the monitoring interface that was ordered with the turbine has been unable to consistently connect with it. Soon after the turbine was operational, the station installed multiple electrical block heaters on their plow trucks for use during the winter months. This ultimately increased the load at the facility. Had this new load been anticipated, a larger turbine might have been procured. The system has per- formed as expected, based on the review of the net metering readings and the monthly bills at the station, accounting for the impact of the block heaters (see Fig ure 22-48). It is saving an estimated Source: Terry Wiseman, Utah DOT. Figure 22-47. Construction of the wind turbine at the Milford Maintenance Station.

200 Renewable Energy Guide for Highway Maintenance Facilities 3,000 kWh to 3,500 kWh of utility-purchased electricity annually, which equates to a utility bill sav- ings of $240 to $280 annually. While the system is running as expected, it is only economical using the U.S. DOE grant. This grant cut the installed cost from $13,500 to $6,500, and resulted in a payback period of 16 years (based on the installed cost after the grant and offset labor). One of the drivers of the economics of this turbine is that Utah has relatively low power rates (about $0.08/kWh average commercial rate), making the electricity generated by the wind turbine generator less valuable than it would be at locations with higher electricity prices. The turbine has not required maintenance. There are upgrades available for the inverter, which would increase the turbine power output. There have also been improvements to the communications equipment that could enable on-site staff to better monitor the wind turbine performance. One lesson learned is that it is very impor- tant to properly study the wind resource and site the turbine appropriately. Given the significant installed cost, this pre-installation analysis is vital. Wind generator system information: • Wind turbine type: Skystream 3.7 • Tower height: 45 m • Design rating: 1.8 kW @20 mph • System cost: $13,500 ($6,500 after DOE grant) • Annual energy savings: 3,000 to 3,500 kWh • Percent of annual electricity met: 25% to 35% • Electric power demand reduction: 1.8 kW • Annual energy operating cost savings: $240 to $280 • Economics: 30+ years (payback period with no grant); 16 years (payback period with grant) • Applicability: sites with suitable wind and land area 1800 Watt Skystream 3.7 Wind Turbine Installed: March 21, 2008 Note: Some plow trucks outside have been plugged in during winter months. Source: Tim Ularich, Utah DOT. Figure 22-48. Comparison of Milford Station 4531 electricity use with wind turbine generator installed.

Individual Case Studies 201 22.8.4 Lessons Learned • Perform a site-specific study to determine the wind resource. • Make sure to accurately forecast facility load requirements, accounting for load growth, to ensure the best match of wind turbine output to facility needs. • Check local ordinances early in the process to assess viability. • Keep the key players involved throughout the process. • Start with a small project to understand what is truly involved with an evolving technology. This can be an important step to building toward larger-scale implementation. • It is important to emphasize energy efficiency as part of the project. • Try to include better energy monitoring to encourage the occupants to practice conservation. • Try to find a way to incentivize employees to conserve energy and other resources. 22.8.5 Future Plans The facility is scheduled to be replaced; the on-site wind resource will hopefully be integrated into the plan for the new facility. 22.9 Case Study: Ohio Department of Transportation, Northwood Outpost Garage Wind Turbine 22.9.1 Overview The Ohio Department of Transportation (Ohio DOT) District 2 manager wanted to implement some form of alternative energy system to offset energy usage at an existing rest area site in the district. Wind, solar, and geothermal sources were considered. After investigation of the site and the avail- able and applicable technologies, a 1.3-kW wind turbine was selected due to the above-average wind resource in northwest Ohio. Upon completion of research on the loads at the site, turbine capacity was increased to 30 kW in order for the turbine to make a significant load reduction. However, during the site review process, the U.S. Fish and Wildlife Service asked that the turbine not be installed at the rest area site due to the proximity to several bird migration paths. Ohio DOT District 2 agreed not to install the turbine at the originally selected site. After researching energy use and costs for several of the existing District 2 facilities, the Northwood Maintenance Facility was identified as having high use and high unit cost for electricity with adequate site area for the turbine. The decision was made to install the turbine at Northwood with unit installation beginning in early 2011. The Ohio DOT Northwood Outpost includes a main building of approximately 31,150 ft2 for housing vehicle maintenance, vehicle washing, and offices. Additionally, there are two equipment storage buildings totaling 8,200 ft2, an open-faced equipment storage building of 6,320 ft2, and 11,520 ft2 of salt storage. All buildings are approximately 20 years old, except one of the equipment storage buildings, which is just over 10 years old. The facility is normally occupied during normal working hours (7:00 a.m.–4:00 p.m.) except during snow and ice conditions, when the facility operates up to 24 hours per day. There are approximately 15 on-site staff and an additional 15 staff who work out of the facility, operating 18 trucks, five mowers, and one loader performing roadway maintenance for 372 lane miles. The facilities are not specifically designed to be of above-average energy efficiency, nor have any sustainable design strategies been incorporated. The repair area has ducted exhaust and typical HVAC controls. The intent of the project was to offset the electrical usage as much as possible, with the target being 65% on an annual basis. Renewable Energy: The project consists of a tower-mounted 32-kW horizontal-axis wind tur- bine with a hub height of 85 ft. The system includes an inverter, switching, and a separate meter to tie to the local electrical grid operated by Toledo Edison (which is part of First Energy in Akron,

202 Renewable Energy Guide for Highway Maintenance Facilities Ohio). The system is sized to meet 65% of the annual electric load of the building. In addition to reduced electrical costs, the system offsets utility-produced electrical energy consumption, generated primarily from coal, resulting in a positive environmental impact. No grant monies or incentives were used to install the approximately $200,000 wind turbine generator. All funding for the project came from state funds allocated to Ohio DOT District 2. Figures 22-49 through 22-52 show photos of the wind turbine generator. Source: Alex Weinandy, Ohio DOT. Figure 22-49. Overview—Ohio DOT Northwood Outpost garage. Source: Alex Weinandy, Ohio DOT. Figure 22-50. View of turbine hub and blades— Ohio DOT Northwood Outpost garage.

Individual Case Studies 203 Source: Alex Weinandy, Ohio DOT. Figure 22-51. View toward I-280—Ohio DOT Northwood. Source: Alex Weinandy, Ohio DOT. Figure 22-52. View from I-280—Ohio DOT Northwood.

204 Renewable Energy Guide for Highway Maintenance Facilities 22.9.2 Project Development Process 22.9.2.1 Pre-Design (Project Planning) Phase The intent of the original project was to demonstrate a renewable energy source at a high- visibility rest area on State Route 2. After consideration of renewable energy resources at the site and alternative technologies, including solar PV, solar thermal, geothermal, and wind, a wind turbine was identified as the best solution. Analysis of electrical loads at the site revealed that the initially selected turbine capacity was inadequate, so a larger turbine was specified. However, during the site analysis, a wind turbine on the site was vetoed by the U.S. Fish and Wildlife Service due to its proximity to migratory bird flyways. Committed to the wind turbine concept, Ohio DOT proceeded to identify an alternative location for the turbine. The Northwood Outpost Garage site, adjacent to Interstate 280, was identified and selected in lieu of the initial Route 2 site. The specified turbine capacity was intended to provide approximately 65% of the annual electrical load at the Northwood site. Coordination between the utility, Ohio Edison, and Ohio DOT resulted in the net-metered connection of the turbine. Planning involved representatives of Ohio DOT District 2 and the Statewide Facilities Division of the Ohio Department of Transportation. The project delivery method was a design–bid–build process using a contractor selected from Ohio DOT’s pre-approved contractor list. Pre-approved contractors bid to a performance specification prepared by Ohio DOT. The selected contrac- tor subsequent to award engaged all design and subcontract work for the installation and was responsible for obtaining permit approvals. The performance specification indicated a 30-kW minimum capacity. The provided turbine is rated at 32 kW, illustrating the potential for a perfor- mance specification to result in an installation that exceeds the minimum established requirements while adhering to the project budget. The key lesson learned during the pre-design phase was to identify and verify any environmental restrictions at the proposed site prior to selecting a particular technology. Additionally, once a technology has been selected, an energy audit to establish the base load will allow accurate sizing of the renewable energy system. Site and Building Information: Location: Northwood, Ohio • Address: 200 Lemoyne Road, Northwood, OH 43619 • ASHRAE climate zone: 5A • Annual heating degree days (65°F base): 6,482 (Bowling Green waste water treatment plant) • Wind power class 2—200–300 w/m2 • Facility floor area: 57,182 ft2 • Occupancy: 30 • Schedule: 9 h/day—5 days/week Renewable Energy Features • Wind turbine, net metered (32 kW) Other Energy Efficiency Features • Ducted exhaust systems Sustainability Features • None

Individual Case Studies 205 22.9.2.2 Design Phase The project was bid as a performance spec to a pre-approved bidders list. The pre-design work determined the size of the turbine and location on the site. The site was able to allow the turbine and tower to meet the 100-ft fall-zone requirement should the tower fail. The successful bidder selected and paid for the design professionals (architect and engineer) to prepare documents for permitting and installation. Since this project was limited to the addi- tion of a wind turbine system to an existing facility, the design only required location of the turbine on the site and documentation necessary to indicate compliance with the appli- cable codes. Compliance with the Ohio Building Code required indication of the structural adequacy of the tower and footings per the International Building Code and compliance of all electrical elements with the National Electrical Code. Due to the proximity of the installation to a regional airport, installation was coordinated with the FAA. However, compliance with FAA requirements did not affect the tower height or other design parameters. Local zoning approval was sought even though Ohio DOT, by virtue of being a state agency, is exempt from local zoning regulations. Based on the wind resource, the wind turbine generator is predicted to yield a payback of 12 to 16 years. The predicted service life of the turbine is 20 years. The turbine has a 1-year warranty from the date of commissioning. The state of Ohio is in the process of putting a maintenance contract out to bid. Although installation was completed in the summer of 2011, the turbine was not able to be commissioned due to a defective part in the turbine. Project Team Building Owner’s Representative Ohio DOT Transport Administrator Ohio DOT Program Manager Ohio DOT Energy Specialist Architect of Record Shremshock Architects, Inc. Consultants Prater Engineering Associates Construction General Contractor Zenith Systems, LLC Wind Turbine Installer LTI Power Systems Wind Turbine TecWind LLC, 32-kW, horizontal-axis, 3-blade machine, manufactured in China Inverter: Aurora model number PVI-6000- OUT-US-W, supplied by TecWind 22.9.2.3 Construction Phase As mentioned previously, project delivery was by the traditional design–bid–build process but limited to contractors on Ohio DOT’s pre-approved contractor list. Since the project was for the renewable energy system only, coordination was limited. To minimize disruption of District 2 activities, there were periodic project schedule and delivery schedule meetings between the contractor and Ohio DOT. Due to the change in location of the system, additional engineering was required as well as rescheduling of the installation. The installation was completed in April of 2011, followed by testing and commissioning of the turbine. There have been control issues with the tie-in to the power grid, resulting in the turbine shutting itself down. The turbine became non-operational due to a mechanical failure. The turbine was not operational as of the end of 2012.

206 Renewable Energy Guide for Highway Maintenance Facilities 22.9.3 Results Ohio DOT is disappointed in the delays in getting the turbine into service. Based on experience thus far, implementation of a service contract for the unit is a high priority. The unit’s perfor- mance will be monitored in-house by Ohio DOT. Since no on-site wind monitoring equipment was specified, system performance will be evaluated based on the net-meter output and locally available wind data (from the local weather station). Ohio DOT is still in the developmental stages of its renewable energy applications. Researching the companies/contractors involved in the manufacture of equipment and construction of renew- able energy projects is critical. On this project, the procurement process did not provide the desired or necessary level of quality control over the project. However, when the project is finally opera- tional, Ohio DOT is anticipating the use of renewable energy will be viewed positively by the public. 22.9.4 Lessons Learned • Buy American if possible, or at a minimum specify that repair parts be stocked and available locally. Ohio DOT has experienced long delays in receiving replacement parts from overseas. • The lowest bid is not always the best bid. • Research the bidder/contractor before it is hired. Specifically, investigate the number of previous successful installations and the relationship with the turbine manufacturer, and contact the references provided. • Specify that the tower be painted the same color as the turbine housing. 22.10 Case Study: Elm Creek Park Maintenance Facility (MN), Geothermal Heat Pump System 22.10.1 Overview The Elm Creek maintenance facility is located in Elm Creek Park Reserve in the Three Rivers Park District in Maple Grove, MN. The maintenance facility serves all of the service vehicles and equipment for the 4,900-acre park and serves as heated storage for three park police vehicles. The maintenance complex includes two other buildings: the old maintenance building and a cold stor- age building. The old maintenance building is currently used for storage for the park’s snowplowing equipment and cold weather equipment. The cold storage building is an uninsulated, four-sided concrete structure with no heat or plumbing that stores snow grooming equipment, snow cats, and snowmobiles. Included in the main maintenance shop are offices for the administrative staff, main- tenance supervisor, facilities supervisor, and crew chiefs (see Figure 22-53). Vehicle and service bays include two mechanic’s bays, a vehicle storage bay, a wash bay, and three bays for park police vehicles. A geothermal well field supplies heat and cooling to the building. The offices are supplied with hot and cold air from two water-to-air heat pumps and a fan unit to distribute the conditioned air. The bays are supplied with heat from three water-to-water heat pumps and a hydronic radiant floor heating system. The system has been redesigned since it was first installed and has had a number of issues going back to the original system and the redesign. Lessons learned were that proper plan- ning and meticulous installation can prevent many problems from occurring, which may prevent sub-optimal system performance. The Three Rivers Park District is currently underway on a new geothermal system for a visitor’s center in the park, which has already benefited from the operations of the other geothermal systems. 22.10.2 Project Development Process 22.10.2.1 Pre-Design (Project Planning) Phase The Three Rivers Park District’s ethos in building park infrastructure is to be as envi- ronmentally conscious as possible while making accessible the great outdoors and related

Individual Case Studies 207 activities. The highlighted project included two buildings, a ski chalet and a maintenance and storage garage. An RFP was sent to a group of eight pre-qualified contractors that Three Rivers Park District uses for projects. Short, Elliott, and Hendrickson, Inc. (SEH), a local design and engineering firm, won the design–bid–build contract. The project requirements included space requirements and office arrangements, and consideration was given to solu- tions that help the Three Rivers Park District reach district-wide sustainability targets by 2050. Although not in place at the time, Three Rivers currently prescribes energy use intensity profiles for new buildings, varying by type, which has led to new geothermal systems being designed and installed. Source: Elm Creek Administrative and Maintenance Center, Elm Creek Park Reserve, Three Rivers Park District. Figure 22-53. Southwest elevation, Elm Creek maintenance facility. Site and Building Information: Location: Maple Grove, Minnesota • Address: 12400 James Deane Parkway, Maple Grove, MN 55369 • ASHRAE climate zone: 6 • Annual heating degree days (65°F base): 7,876 • Annual cooling degree days: 699 • Winter (Oct.–March) high: 36°F/avg.: 28°F/low: 19°F • Summer (April–Sept.) high: 74°F/avg.: 63°F/low: 53°F • Average annual precipitation: 29.41 in. • Facility floor area: 11,767 ft2 • Schedule: 24/7 Renewable Energy Features • Geothermal heat pumps Other Energy Efficiency Features • VFD drives on compressor motors and system pumps • Building automation system • Building envelope and systems designed to reduce energy consumption • Hydronic radiant floor heating in combination with variable air volume tempered ventilation system Sustainability Features • Designed for low CO2 emissions

208 Renewable Energy Guide for Highway Maintenance Facilities 22.10.2.2 Design Phase During the design of the facility, SEH proposed a pond-loop geothermal system for the maintenance shop and a horizontal coil geothermal field for the chalet. This system would cost slightly more up front than the alternative gas boiler system but was projected to save money over the lifetime of the building. The Three Rivers Park District had enough latitude in the building budget that they opted to spend the money on the geothermal system instead of proceeding with a conventional build. Another benefit, especially in regard to the maintenance garage, was that the radiant slab would be heated in the winter, which would allow for a more comfortable working environment for the mechanics during the long heat- ing season. The geo-source system, in its preliminary design presented by SEH during design develop- ment, was expected to save an estimated $2,200 in annual operating costs (heating and cooling) compared to a conventional HVAC system with natural gas (assumed current energy costs, no inflation). The geothermal equipment was estimated at $60,000 to $70,000 initial cost, which included heat pumps, loop piping, pumps, glycol, and so forth. The contractor’s schedule of val- ues indicated a total mechanical (HVAC) cost of $200,000. This cost normally would include all the geo-source equipment as well as the ductwork, fans, controls, in-floor radiant piping, and so forth. It is impossible to delineate the true portion of cost of the geo-source equipment from this overall number. Project Team Building Owner’s Representative Senior Manager, Architecture Three Rivers Park District Architect Short, Elliott, & Hendrickson, Inc. General Contractor Lund-Martin Construction, Inc. Geothermal Installer—Pond UMR Geothermal Geothermal Installer—Ground Loop Dedicated Geothermal, LLC The design team was led by SEH project manager and a project representative. The project manager was instrumental in producing a design for the maintenance facility that used geothermal heat pumps to heat a radiant slab in the storage, maintenance, and wash bays of the facility. With interest from Three Rivers Park District in geothermal, a reasonable projected payback, and the stated goals of the park, a geothermal pond loop was selected. The original ground side of the geothermal heating and cooling system was designed to be sub- merged in a 1.4-million-gallon, lined, manmade pond adjacent to the new maintenance building and near the ski chalet. The water-side loop was to feed three Econa water-to-water heat pump units and two water-to-air heat pumps. The water-to-air heat pumps produce hot and cold air for the offices and preheat a makeup air unit in the garage spaces. The makeup air unit also has a natural gas–fired heating element that comes on when the heating rate outpaces the capacity of the geothermal preheat coil. This pond is used in the winter for snowmaking and is replenished when necessary from the municipal water supply. In the winter, the pond is kept at or near 34°F, which helps the efficiency of the snowmaking equipment. Theoretically, extracting heat from the bottom of the pond

Individual Case Studies 209 during winter would assist with thermal management of the water while simultaneously provid- ing heat for the maintenance facility. The depth and volume of a pond are important factors in heat capacity. A pond with a large surface area will be colder in the winter and warmer in the summer than one of the same volume that is deeper. The snowmaking pond has a depth of about 12 ft. The original water-source heat exchanger design called for two sleds of plastic loops to collect warmth during the winter months and dissipate heat during the summer. The original designer of the system had departed the firm when the plans were finalized, however, and the two sleds were replaced with a single, 35-ton capacity, pre-manufactured stainless steel heat exchanger unit. The manufacturer of the unit, the manufacturer of the heat pumps, and the engineering firm calculated that this unit would provide the equivalent heating and cooling capacity of the plastic coil units. Figures 22-54 through 22-59 show various aspects of the geothermal heat pump systems from construction through completion of the installation. 22.10.2.3 Construction Phase The maintenance garage was constructed in 2006 and the spring of 2007 with a combination of concrete masonry unit blocks and poured concrete construction and incorporated hydronic Source: Elm Creek Administrative and Maintenance Center, Elm Creek Park Reserve, Three Rivers Park District. Figure 22-54. Plate exchanger. Source: Elm Creek Administrative and Maintenance Center, Elm Creek Park Reserve, Three Rivers Park District. Figure 22-55. Pond with heat exchange piping.

210 Renewable Energy Guide for Highway Maintenance Facilities Source: Elm Creek Administrative and Maintenance Center, Elm Creek Park Reserve, Three Rivers Park District. Figure 22-56. Drilling rigs during installation of vertical well field. Source: Elm Creek Administrative and Maintenance Center, Elm Creek Park Reserve, Three Rivers Park District. Figure 22-57. Two water-to-air heat pumps supply the office spaces. radiant pipes in the poured concrete slabs of the vehicle bays. Five heat pumps were installed— three water-to-water units to heat the vehicle bays and two water-to-air units to heat and cool the air for the offices. Because of the relatively short cooling season, no cooling was designed for the garage bays. The heat exchanger was installed in the pond. Because the 1.4-million-gallon pond is a lined, manmade pond wholly owned by the Three Rivers Parks District, no permit was necessary. However, had the pond been a natural lake or otherwise owned by the Minnesota Department of Natural Resources, a permit from the Department of Natural Resources and an environmental impact analysis would have been required.

Individual Case Studies 211 Source: Elm Creek Administrative and Maintenance Center, Elm Creek Park Reserve, Three Rivers Park District. Figure 22-58. Three water-to-water heat pumps supply heat to the radiant heating system in the vehicle bays. Source: Elm Creek Administrative and Maintenance Center, Elm Creek Park Reserve, Three Rivers Park District. Figure 22-59. Installation of geothermal wells and piping.

212 Renewable Energy Guide for Highway Maintenance Facilities The system initially appeared to be working quite well, but filters quickly filled up with a sludge that was supposedly caused by impurities or additives to the city water supply precipitating out of the ethylene glycol mixture. This sludge continued to accumulate in the filters, which had to be cleaned periodically, for a few months before the phenomenon stopped. The water temperature in the pond was highly elevated (estimated in the mid-80°F range by the end of the first summer of operation, which decreased the efficiency of the heat pump units). During the heating season, as the pond temperature dropped and was maintained for snowmaking purposes, the water-side heat exchanger began having issues with freezing the surrounding water, which greatly decreased the efficiency of heat transfer and led to the maintenance facility being under-heated. An engineer programmed the system to reverse the flow for 2 hours overnight, heating the pond and preventing the heat exchanger from freezing over. The periodic nighttime cooling of the building to keep the heat exchanger free from pond ice was not a viable long-term option since it led to the building being under-heated and was relatively energy intensive. After two heating seasons, the decision was made in 2008 to abandon the pond loop and install a vertical well system instead. The new ground-side loop consisted of 36 175-ft vertical wells that housed high-density polyethylene (HDPE) pipe loops, which were then plumbed to the existing water-source heat pump units. This array of 175-ft wells was permitted by the Minnesota Department of Health, with a specific permit for use as a heat exchanger. The wells were filled with bentonite/silica sand grout, a common prac- tice where ground wells are required to be sealed from the water table. When the ground loops were installed, a proper flushing was not performed by the installation contractor, which would have consisted of a high volume of fluid moving through the pipes to dislodge any debris that may have been knocked in during construction. As a result, a fair amount of debris from the well field that had fallen into pipes during construction remained in the system, and eventually made its way into the heat pump filters. Each time one of the filters became impacted enough to constrict flow, the corresponding heat pump had to be taken out of service to clean the filter. Shortly after commissioning, this happened frequently, but over time became an infrequent occurrence. In addition to the flushing problem, another side effect of changing from a pond to a ground-loop system was that a portion of the first system’s ethylene glycol remained, which had an adverse effect on the new propylene glycol heat transfer fluid. Despite these setbacks, the geothermal system did provide adequate heat to the building, and backup heating was not required. The system is currently running as it should and is satisfactorily heating the vehicle bays and heating and cooling the office spaces. 22.10.3 Results The Elm Creek maintenance facility, despite the flaws in execution of the geothermal system, still touts energy consumption that is better than similar building types within Three Rivers Park District. A direct comparison to the Hyland and Baker facilities—the other two operations and mainte- nance facilities owned and operated by Three Rivers Park District—is not possible because each case varies greatly in either layout’s operating schedule. These have conventional non-geo-source heating and cooling systems. Elm Creek is the only one of the three maintenance centers that also houses a public safety function and a winter recreation (ski hill) maintenance function. Both of these functions at Elm Creek require 24-hour operations, with especially intense use during the winter season for the maintenance function.

Individual Case Studies 213 Hyland includes approximately 6,500 ft2 of unheated storage with very low energy use inten- sity. Therefore, the average kBtu/ft2/year at Hyland is significantly decreased compared to Elm Creek (total kBtu/year at Hyland = 1,010,265/15,000 ft2 = 67 kBtu/ft2/year). A true comparison cannot be made between the two buildings unless the energy used by the unheated storage space (ventilation and lighting) can be separated from the rest of the Hyland facility energy. Baker is a more apt comparison in size than Hyland, but does not support 24/7 activities nor does it have as intense winter use. At Baker, all staff are present for day shifts plus single custodian evening shifts 8 months of year. For 4 months of the year, a couple of staff are added to the evening shift on weekends. Baker has had a number of energy-saving retrofits, including a lighting retrofit for high-bay spaces completed in 2010. Elm Creek will receive the same retrofit by 2013. Baker has a program- mable thermostat to control nighttime setback temperatures. Baker’s energy use, while very comparable to Elm Creek’s, is less efficient per occupant-hour: • Elm Creek Administrative and Maintenance Center (2007): 11,767 ft2; consumes 63 kBtu/ft2/ year. • Hyland Maintenance Center (1998): 21,495 ft2; consumes 47 kBtu/ft2/year. • Baker Administrative and Maintenance Center (2000): 12,754 ft2; consumes 64 kBtu/ft2/year. 22.10.4 Lessons Learned As a result of some of the early failures and inconsistencies from this system, a number of lessons have been applied to the park district’s policies toward future geothermal projects. Some of these are: • Perform soil conductivity tests before considering geothermal heating and cooling. • Use premixed, pre-diluted geothermal heat exchange fluid (glycol mix). Additives to the municipal water supply can act as contaminants in a sensitive system. Elm Creek Administrative and Maintenance Center Schedule 7 days per week Maintenance: Snowmaking (Approximately 3 Months) 24 h continuous occupancy for 10 people day shift, three to five people on evening and overnight shift Maintenance: Normal Operations (approximately 9 months) 20 h/day—15 people day shift, three to five people on evening shift Public Safety (year round) Three to four people day/evening shift (approximately 3 months) One person 24/7 (night shift) Total Staff Operating out of Building 21 to 22 maintenance, four to six public, two to three other administrative (day shift only)

214 Renewable Energy Guide for Highway Maintenance Facilities • To ensure that the entire system will work as planned, extreme caution must be used when changing a design for a geothermal heat exchanger. (There is speculation on the part of SEH that the original heat exchanger loops may have been a better solution than the plate heat exchanger.) • Require VFDs on pumps. • Extreme care needs to be taken in installation of well field loops to prevent contamination. • Proper flushing of well field loops is critical for system performance. • Strainers and expansion tanks are now a required part of system design. • Water-to-air units had fewer problems than water-to-water units, but radiant floor heat is a more efficient and comfortable way of heating large open spaces. • Thorough research on equipment manufacturers is encouraged to ensure the quality of installed equipment. Manufacturer and installation contractor support are both key elements in any unplanned circumstances. • Install accessible valves for different heating zones. The police bays tend to be overheated and could have been cut off during shoulder months if zone valves had been installed with the in-floor radiant piping. 22.11 Case Study: Kilauea Military Camp, HI, Corrosion-Resistant Roof with Integrated Photovoltaic System 22.11.1 Overview KMC is located within Volcanoes National Park, HI. Many of the buildings at KMC have metal roofs that have experienced significant corrosion. Building 84 was selected as a test bed to determine the impacts of a roof-integrated thin-film solar photovoltaic system on the roof corrosion resistance of today’s metal roofing and high-performance coatings. In addition, the electrical performance of the PV roofing system would be assessed. Building 84, which was constructed in 1946, is a 5,500-ft2 vehicle storage structure with some office and storage space on the east and west ends of the facility. The facility is not heated or cooled, except for the office area, though it does have electricity for general- purpose lighting and electrically operated equipment. The building is occupied 9 h/day, 5 days/week by five to 10 people. The roof-integrated photovoltaic system consists of 200 panels (eight strings of 20 panels and four strings of 10 panels) of thin-film amorphous silicon photovoltaic modules lami- nated to an aluminum-zinc coated standing seam metal roof (SSMR) with a polyvinylidene fluoride (PVDF) fluorocarbon anti corrosion coating. The photovoltaic system is rated at 15 kW, and the solar- generated electricity is converted from DC to AC power by use of an inverter. To evaluate corrosion resistance performance over time, several material coupons and a functional PV roofing panel were installed on a ground-mounted rack. The electrical performance of the system is being monitored, and the results indicate that the system is performing as designed. Over the first year of opera- tion, 19,128 kWh were generated by the system, with a daily average of 52.4 kWh. The associ- ated energy operating cost savings is $6,729 with local electricity rates at $0.3518/kWh. Thus far, the roofing system has not exhibited any signs of corrosion. The PV system cost was $195,674 (excluding all roofing costs). The cost and savings equate to a simple payback period of 29 years. The system construction was relatively straightforward, with attachment of some of the PV panels to the SSMR taking place on the ground, and attachment of others taking place after the roofing was installed. Overall, the system appears to be operating well, with little maintenance requirements. It appears to be a potentially good solution for a versatile roofing power-generation system. Lessons learned include the need to prioritize the permitting process to allow for connection to the power grid, which has potential to delay project completion, and the awareness that PV panels are suscep- tible to breaks, which can necessitate sealing them, at the cost of reducing efficiency. Figures 22-60 and 22-61 show the roof-integrated photovoltaic system and the material layers used in the thin-film photovoltaic collectors, respectively.

Individual Case Studies 215 Source: Materials and Structures Branch of the Construction Engineering Research Laboratory – Engineer Research and Development Center. Figure 22-60. Close-up of roof-integrated thin-film photovoltaic system. Site and Building Information: Location: Volcanoes National Park, Hawaii • Address: Kilauea Military Camp, Volcanoes National Park, HI 96718 • ASHRAE climate zone: 1A • Annual heating degree days (65°F base): 10 • Average high temperature/low temperature (summer): 83.2°F/68.3°F • Average high temperature/low temperature (winter): 71.9°F/63.8°F • Average annual precipitation: 126.3 in. • Building floor area: 5,500 ft2 • Occupancy: 5 to 10 • Schedule: 9 h/day Renewable Energy Features • Roof-integrated thin-film photovoltaic system Figure 22-61. Thin-film photovoltaic collectors by Uni-Solar. Source: Materials and Structures Branch of the Construction Engineering Research Laboratory – Engineer Research and Development Center.

216 Renewable Energy Guide for Highway Maintenance Facilities 22.11.2 Project Development Process 22.11.2.1 Pre-Design (Project Planning) Phase The project was conceived by the Engineer Research and Development Center–Construction Engineering Research Laboratory (ERDC-CERL) as a means of demonstrating a poten- tially promising solution for meeting the power needs of military facilities located in marine environments. Metal roofs are widely used on a variety of military facilities, including vehicle storage and maintenance facilities. An ongoing problem in marine environments is the deg- radation of metal roofs due to corrosion. While there are many anticorrosion roof coating materials in use today, the impact of roof-integrated thin-film photovoltaic systems on metal roof corrosion had not been researched. Given the attractive properties of thin-film photovol- taic materials, particularly their relatively light weight and their ability to be mounted on metal substrates without requiring roof penetrations and attachment structures, the Army decided to perform corrosion and performance tests on a typical application. The KMC was identified as a good location for the test, given the climate and the need for alternative energy power sources, which are primarily driven by the very high electricity prices (in excess of $0.25/kWh). The project team consisted of ERDC-CERL, Mandaree Enterprise Corporation, and subcontractors. A fixed-price design–build approach was used. The photovoltaic system and metal reroofing project was bid competitively based on performance specifications, although there were no specific energy-monitoring equipment requirements. The sponsors of the project, which was performed under the Department of Defense Corrosion Prevention and Control Program, included the Office of Under Secretary of Defense, Office of Corrosion Policy and Oversight; Deputy Assistant Secretary of the Army Acquisition Policy and Logistics; Assistant Chief of Staff for Installation Management and Headquarters; and U.S. Army Installation Manage- ment Command. 22.11.2.2 Design Phase The design was created by Mandaree Enterprise Corporation and their subcontractors. A major area of focus was how to integrate the panels into the roof design without sacrificing the corrosion resistance of the structure. The first step was to commission an engineering study of the new roofing system. It was determined that the design wind load was a 3-second, 105-mph gust at a 50-year mean recurrence interval. The existing roof framing system was inadequate to support this load so it was replaced. A PV system configuration was specified to optimally fit the building. In order to accommodate the larger area of the shed roof section, the design team chose a larger PV cell bank configuration, made up of four strings of 10 panels. These panels were the Uni-Solar PVL-144 solar cells, which have a total output rating of 7.2 kW. These cells were too long to fit on the gabled roof section, so a bank configuration of eight strings of 20 Uni-Solar PVL-68 solar cells was used. These cells have a total output rating of 10.9 kW. The system was designed to be connected through the grid by an inverter, capable of supplying power to the building or back to the grid. Additionally, a wireless monitoring capability was integrated into the design to track the power characteristics of the system. 22.11.2.3 Construction Phase The existing roof on Building 84 at KMC was replaced with an aluminum-zinc–coated SSMR with a Durapon 70 PVDF fluorocarbon coating on the external-facing surface. For the gable roof section, the solar panels were assembled on the ground and then installed on the roofing panels and finally wired to an inverter and connected to the grid. For the shed roof section, the solar panels were adhered after the roof panels were installed. When the power produced exceeds the building’s needs, the excess is sent to the grid for use by other buildings

Individual Case Studies 217 at KMC. There is no means for energy storage within the system. Due to permitting and tech- nical issues, the activation of the inverter was delayed until December 2010, and monitoring did not begin until January 2011. The corrosion performance of the roof is evaluated by periodic visual examination of the completed roof, by examination of exposure coupons mounted on-site, and by laboratory testing of coupons of the roofing material. Performance monitoring of the PV system was accomplished through the use of a remote module manufactured by Fat Spaniel, Inc. In addition, sensors are mounted on a functional PV roofing panel installed on an exposure rack on-site at KMC. These sensors allow the recording of corrosion conditions between the thin-film PV cells and the roof surface. Figures 22-62 through 22-66 illustrate the construction of the roof-integrated photovoltaic system. Source: Materials and Structures Branch of the Construction Engineering Research Laboratory – Engineer Research and Development Center. Figure 22-62. Building 84 prior to installation of the roof-integrated thin-film photovoltaic system. Source: Materials and Structures Branch of the Construction Engineering Research Laboratory–Engineer Research and Development Center. Figure 22-63. Building 84 roof construction.

218 Renewable Energy Guide for Highway Maintenance Facilities Source: Materials and Structures Branch of the Construction Engineering Research Laboratory– Engineer Research and Development Center. Figure 22-64. Individual SSMR panels with photovoltaic panel attached prior to mounting. Source: Materials and Structures Branch of the Construction Engineering Research Laboratory – Engineer Research and Development Center. Figure 22-65. Installation of the SSMR panels on roof. Source: Materials and Structures Branch of the Construction Engineering Research Laboratory – Engineer Research and Development Center. Figure 22-66. Inverter and associated hardware.

Individual Case Studies 219 22.11.3 Results Remote monitoring was used to monitor electrical generation performance. From this monitoring, it has been observed that the system is performing as expected. It has been produc- ing on average 52.4 kWh daily for the first 2 months of operation. This will put it roughly in line with the expected annual output of 19,128 kWh. Additionally, the PV material has proven to be an effective barrier to moisture intrusion and corrosion initiation. While some additional maintenance is required to ensure that the cells remain sealed, the system has shown promising early results. Photovoltaic System • PV system type: thin-film amorphous silicon • PV system rated capacity: 15 kW • PV system area: 2,860 ft2 • System cost: $195,674 • Annual energy saved: 19,128 kWh • Annual energy operating cost savings: $6,729 (elec. @ $0.3518/kWh) • Economics: 29 years (payback period) • Applicability: buildings that have metal roofs The daily electricity output of the photovoltaic system from January 20, 2011, to March 24, 2011, is shown in Figure 22-67. 22.11.4 Lessons Learned • The permitting process is a critical-path item, and more likely to be a cause of delay than tech- nical or construction issues. This is especially true in situations (like this one) where there are multiple parties responsible for taking necessary actions or providing necessary information, some of whom have no vested interest in the project. • If breaks occur in the material’s surface, the cells are extremely vulnerable to intra-cell corrosion. This vulnerability within the cells dictates that any breaks should be sealed at once, even if this sealing occurs at a cost of reduced operational efficiency of that particular cell. Project Team Building Owner’s Representative Kilauea Military Camp Maintenance Mechanic Supervisor DPW-KMC Engineering/Maintenance Shop Design Construction Engineering Research Laboratory U.S. Army Engineer Research and Development Center Mandaree Enterprise Corporation Penta Engineering Group, Inc. Construction General Contractor Ultimate Roofing PV System Supplier/Installer Hawaii Solar Roofing, LLC PV System Manufacturer Uni-Solar

220 Renewable Energy Guide for Highway Maintenance Facilities Source: Materials and Structures Branch of the Construction Engineering Research Laboratory–Engineer Research and Development Center. Figure 22-67. System electricity output.

221 Hot water heating loads can be determined from knowledge of the quantity of hot water required, the delivery temperature of the hot water, and the temperature of the cold water input, as follows: • Annual hot water (Btu) = annual gallons × 1.0 Btu/lb-°F × 8.33 lbs/gal × (Tout–Tin), where Tout and Tin are the delivery and input temperatures in degrees Fahrenheit, and annual gallons is the amount of hot water used annually in gallons. The cold water input temperatures can be approximated from maps of groundwater (see Figure A-1) A P P E N D I X A Hot Water Load Estimation Source: DOE FEMP: Federal Technology Alert: Solar Water Heating. Figure A-1. Groundwater temperature in degrees Fahrenheit in wells ranging from 50 ft to 150 ft in depth.

222 Renewable Energy Guide for Highway Maintenance Facilities Source: 2010 Solar Technologies Market Report, 2011, p. 67, http://www.nrel.gov/docs/fy12osti/51847.pdf. Figure A-2. Photovoltaic system cost data by module type. Source: 2010 Solar Technologies Market Report, 2011, p. 66, http://www.nrel.gov/docs/fy12osti/51847.pdf. Figure A-3. Photovoltaic system cost data. Source: Barbose, Darghouth, and Wiser, 2012. Figure A-4. Photovoltaic system cost trend.

Hot Water Load Estimation 223 Table A-1. Biomass—wood chip/pellet cost data (backup). Parameter Wood Chips Bulk Wood Pellets Propane Fuel cost $50/ton $200/ton $2.50/gal Fuel heat content 12.2 MMBtu/ton 16.4 MMBtu/ton 92,000 Btu/gal Fuel consumed 49 tons 37 tons 7,000 gal Annual fuel cost (513 MMBtu) $2,800 $7,400 $17,500 System O&M cost $1,500 $1,500 $500 First year cost savings $13,900 $9,400 n/a Simple system payback 8 years 11 years n/a Total cost savings over 15 years vs. propane1 $168,000 $82,400 n/a 1Inflation rate trend for propane is 5.25% and for wood fuel is 3.25%; existing propane boiler is assumed to be 80% efficient, and wood boiler is 85% efficient. Source: Containerized Wood Boiler Case Study, http://www.actbioenergy.com/brochure/Containerized%20Wood %20Boiler%20Case%20Study.pdf.

224 Absorber: the component of a solar thermal collector that absorbs solar radiation and converts it to heat, or, as in a solar photovoltaic device, the material that readily absorbs photons to generate charge carriers (free electrons or holes). Active Solar Heater: a solar water or space heating system that use pumps or fans to circulate the fluid (water or heat transfer fluid like diluted antifreeze) from the solar collectors to a storage tank subsystem. Air Collector: in solar heating systems, a type of solar collector in which air is heated in the collector. Albedo: the ratio of light on a surface to light reflected from it. For sunlight this is the same as solar reflectance. Light-colored surfaces have relatively high albedos and are effective in applications such as cool roofs. Alternating Current: a type of electrical current, the direction of which is reversed at regular intervals or cycles; in the United States the standard is 120 reversals or 60 cycles per second; typically abbreviated as AC. Angle of Incidence: in reference to solar energy systems, the angle at which direct sunlight strikes a surface; the angle between the direction of the sun and the perpendicular to the surface. Sunlight with an incident angle of 90 degrees tends to be absorbed, while lower angles tend to be reflected. Angle of Inclination: in reference to solar energy systems, the angle that a solar collector is posi- tioned above horizontal. Antifreeze Solution: a fluid, such as methanol, ethylene glycol, or propylene glycol, added to engine coolant or used in solar heating systems as a heat transfer fluid, to protect the system from freezing. Antireflection Coating: a thin coating of a material applied to a photovoltaic cell surface that reduces the light reflection and increases light transmission. Aperture: an opening; in solar collectors, the area through which solar radiation is admitted and directed to the absorber. Array (Solar): any number of solar photovoltaic modules or solar thermal collectors or reflectors connected together to provide electrical or thermal energy. Average Wind Speed (or Velocity): the mean wind speed over a specified period of time. Glossary102 102The DOE/EERE energy terms glossary (http://www1.eere.energy.gov/site_administration/glossary.html) was a major source; other definitions supplied by the authors.

Glossary 225 Azimuth (Solar): the angle between true south and the point on the horizon directly below the sun. Balance-of-System: in a renewable energy system, refers to all components other than the mecha- nism used to harvest the resource (such as solar collectors, photovoltaic panels, or a wind turbine). Batch Heater: this simple passive solar hot water system consists of one or more storage tanks placed in an insulated box that has a glazed side facing the sun. A batch heater is mounted on the ground or on the roof. Some batch heaters use selective surfaces on the tank(s). These surfaces absorb sun well but inhibit radiative loss. Also known as bread box systems or integral collector storage systems. Battery: an electric energy storage device composed of one or more electrolyte cells. Biogas: a combustible gas created by anaerobic decomposition of organic material, composed primarily of methane, carbon dioxide, and hydrogen sulfide. Biomass: as defined by the Energy Security Act (PL 96-294) of 1980, “any organic matter which is available on a renewable basis, including agricultural crops and agricultural wastes and res- idues, wood and wood wastes and residues, animal wastes, municipal wastes, and aquatic plants.” Biomass Energy: energy produced by the conversion of biomass directly to heat or to a liquid or gas that can be converted to energy. Biomass Fuel: biomass converted directly to energy or converted to liquid or gaseous fuels such as ethanol, methanol, methane, and hydrogen. Biomass Gasification: the conversion of biomass into a gas, by biogasification or thermal gasifica- tion, in which hydrogen is produced from high-temperature gasifying and low-temperature pyrolysis of biomass. Building Envelope: the structural elements (walls, roof, floor, foundation) of a building that encloses conditioned space; the building shell. Capacity Factor: the ratio of the actual annual electricity produced by a power generator to the annual electricity that could have been generated assuming the generator was operating at its nameplate or design output rating for all hours of the year. Capacity factors of solar electric power and wind power systems tend to be lower (0.2 to 0.3) than conventionally fueled generators due to the variability of the renewable resource. Renewable electricity systems can use energy storage to increase their capacity factors. Central Receiver Solar Power Plants: also known as power towers, these use fields of two-axis tracking mirrors known as heliostats. Each heliostat is individually positioned by a com- puter control system to reflect the sun’s rays to a tower-mounted thermal receiver. The effect of many heliostats reflecting to a common point creates the combined energy of thousands of suns, which produces high-temperature thermal energy. In the receiver, mol- ten nitrate salts absorb the heat energy. The hot salt is then used to boil water to steam, which is sent to a conventional steam turbine generator to produce electricity. Charge Controller: an electronic device that regulates the electrical charge stored in batteries so that unsafe overcharge conditions for the batteries are avoided. Clerestory: a window located high in a wall near the eaves that allows daylight into a building interior; may be used for ventilation and solar heat gain. Closed-Loop Geothermal Heat Pump Systems: closed-loop (also known as indirect) systems circulate a solution of water and antifreeze through a series of sealed loops of piping. Once the heat has been transferred into or out of the solution, the solution is recirculated. The

226 Renewable Energy Guide for Highway Maintenance Facilities loops can be installed in the ground horizontally or vertically, or they can be placed in a body of water such as a pond. See horizontal ground loop, vertical ground loop, Slinky ground loop, and surface water loop for more information on the different types of closed-loop geothermal heat pump systems. Combined Heat and Power: an electric power generation system that also provides heating through the capture of waste heat from the power generation process. Cooling Degree Day: a value used to estimate interior air cooling requirements (load) calcu- lated as the number of degrees per day (over a specified period) that the daily average temperature is above 65°F (or some other, specified base temperature). The daily average temperature is the mean of the maximum and minimum temperatures recorded for a specific location for a 24-hour period. Current Dollars: the value or purchasing power of a dollar that has not been reduced to a com- mon basis of constant purchasing power but instead reflects anticipated future inflation; when used in computations, the assumed inflation rate must be stated. Darrieus (Wind) Machine: a type of vertical-axis wind machine that has long, thin blades in the shape of loops connected to the top and bottom of the axle; often called an eggbeater windmill. Degree Day: a unit for measuring the extent that the outdoor daily average temperature (the mean of the maximum and minimum daily dry-bulb temperatures) falls below (in the case of heating, see heating degree day) or falls above (in the case of cooling, see cooling degree day) an assumed base temperature, normally taken as 65°F unless otherwise stated. One degree day is counted for each degree below (for heating) or above (for cooling) the base for each calendar day on which the temperature goes below or above the base. Diffuse Solar Radiation: sunlight scattered by atmospheric particles and gases so that it arrives at the earth’s surface from all directions and cannot be focused. Direct-Beam Radiation: solar radiation that arrives in a straight line from the sun. Direct Gain: the process by which sunlight directly enters a building through the windows and is absorbed and stored in massive floors or walls. Direct Solar Water Heater: these systems use water as the fluid that is circulated through the collector to the storage tank. Also known as open-loop systems. Discounting: a method of financial and economic analysis used to determine present and future values of investments or expenses. Distributed Generation: a term used by the power industry to describe localized or on-site power generation. Domestic Hot Water: water heated for residential washing, bathing, and so forth. Double-Wall Heat Exchanger: a heat exchanger in a solar water heating system that has two distinct walls between the heat transfer fluid and the domestic water to ensure that there is no mixing of the two. Downwind Wind Turbine: a horizontal-axis wind turbine in which the rotor is downwind of the tower. Drain-Back (Solar) Systems: a closed-loop solar heating system in which the heat transfer fluid in the collector loop drains into a tank or reservoir whenever the booster pump stops to protect the collector loop from freezing. Drain-Down (Solar) Systems: an open-loop solar heating system in which the heat transfer fluid from the collector loop and the piping drain into a drain whenever freezing condi- tions occur.

Glossary 227 Emissivity: the ratio of the radiant energy (heat) leaving (being emitted by) a surface to that of a black body at the same temperature and with the same area; expressed as a number between 0 and 1. Energy Conservation: the use of less energy by reducing the output requirements of an energy system. An example is a reduction in the temperature set point for a thermostat that results in reduced heating energy requirements. A reduction in lighting energy by strategically reducing or turning off lights is another example of energy conservation. Energy Efficiency: the use of less energy for a given output through reductions in a system’s energy losses. For example, a higher efficiency boiler or furnace will require less fuel to meet the same heating requirement as a less efficient boiler or furnace. Energy Intensity: the relative extent that energy is required for a process. Examples of energy intensity are the energy requirement per unit of product manufactured or per dollar of investment or per hour of labor or per unit floor area of facility. Evacuated-Tube Collector: a solar collector made up of rows of parallel, evacuated glass tubes. Each tube consists of a glass outer tube and an inner tube, or absorber. The absorber is covered with a selective coating that absorbs solar energy well but inhibits radiative heat loss. The air is withdrawn (evacuated) from the space between the tubes to form a vacuum, which eliminates conductive and convective heat loss. Evacuated-tube collectors are used for active solar thermal systems. Fenestration: the arrangement or layout of windows in a building. Flat Plate Solar Thermal/Heating Collectors: large, flat boxes with glass covers and dark-colored metal plates inside that absorb and transfer solar energy to a heat transfer fluid. This is the most common type of collector used in solar hot water and space heating systems. Flywheel: a massive disk that, when coupled to a generator, can be used to convert electrical energy into kinetic energy for storing the electricity for later use. Foot Candle: the illumination on a 1-ft2 surface on which there is a uniform light flux distribu- tion of 1 lumen (lumen/square foot). Francis Turbine: a type of hydropower turbine that contains a runner that has water passages through it formed by curved vanes or blades. As the water passes through the runner and over the curved surfaces, it causes rotation of the runner. The rotational motion is trans- mitted by a shaft to a generator. Fresnel Lens: an optical device for concentrating light that is made of concentric rings that are faced at different angles so that light falling on any ring is focused to the same point. Fuel Cell: an electrochemical device that converts chemical energy directly into electricity. Full Sun: the amount of power density in sunlight received at the earth’s surface at noon on a clear day (about 1,000 W/m2). Geothermal Energy: energy produced by the internal heat of the earth; geothermal heat sources include hydrothermal convective systems, pressurized water reservoirs, hot dry rocks, manual gradients, and magma. Geothermal energy can be used directly for heating or to produce electric power. Geothermal Heat Pump: a type of heat pump that uses the ground, groundwater, or ponds as a heat source and heat sink, rather than outside air. Ground or water temperatures are more constant and are warmer in winter and cooler in summer than air temperatures. Geothermal heat pumps operate more efficiently than conventional or air-source heat pumps. Gigawatt (GW): a unit of power equal to 1 billion watts; 1 million kilowatts, or 1,000 megawatts.

228 Renewable Energy Guide for Highway Maintenance Facilities Glazing: transparent or translucent material (glass or plastic) used to admit light and/or to reduce heat loss; used for building windows, skylights, or greenhouses, or for covering the aperture of a solar collector. Green Certificates: represent the environmental attributes of power produced from renewable resources. By separating the environmental attributes from the power, clean power genera- tors are able to sell the electricity they produce to power providers at a competitive market value. The additional revenue generated by the sale of the green certificates covers the above- market costs associated with producing power made from renewable energy sources. Also known as green tags, renewable energy certificates, and tradable renewable certificates. Ground Loop: in geothermal heat pump systems, a series of fluid-filled plastic pipes buried in the ground or placed in a body of water near a building. The fluid within the pipes is used to transfer heat between the building and the ground (or water) in order to heat and cool the building. Ground Reflection: solar radiation reflected from the ground onto a solar collector. Ground-Source Heat Pump: (See Geothermal Heat Pump) Horizontal Ground Loop: in this type of closed-loop geothermal heat pump installation, the fluid-filled plastic heat exchanger pipes are laid out in a plane parallel to the ground sur- face. The most common layouts either use two pipes, one buried at 6 ft and the other at 4 ft, or two pipes placed side-by-side at 5 ft in the ground in a 2-ft-wide trench. The trenches must be at least 4 ft deep. Horizontal ground loops are generally most cost-effective for residential installations, particularly for new construction where sufficient land is available. Also see closed-loop geothermal heat pump systems. Hub Height: the height above the ground that a horizontal-axis wind turbine’s hub is located. Hybrid System: a renewable energy system that includes two different types of technologies that produce the same type of energy (e.g., a wind turbine and a solar photovoltaic array combined to meet a power demand). Hydroelectric Power Plant: a power plant that produces electricity by the force of water falling through a hydro turbine that spins a generator. Impulse Turbine: a turbine that is driven by high-velocity jets of water or steam from a nozzle directed to vanes or buckets attached to a wheel. (A Pelton wheel is an impulse hydro turbine.) Incident Solar Radiation: the amount of solar radiation striking a surface per unit of time and area. Indirect Solar Gain System: a passive solar heating system in which the sun warms a heat stor- age element, and the heat is distributed to the interior space by convection, conduction, and radiation. Indirect Solar Water Heater: these systems circulate fluids other than water (such as diluted antifreeze) through the collector. The collected heat is transferred to the household water supply using a heat exchanger. Also known as closed-loop systems. Insolation: the solar power density incident on a surface of stated area and orientation, usually expressed as watts per square meter or Btu per square foot per hour. Integral Collector Storage System: this simple passive solar hot water system consists of one or more storage tanks placed in an insulated box that has a glazed side facing the sun. An integral collector storage system is mounted on the ground or on the roof. Some systems use selective surfaces on the tank(s). These surfaces absorb sun well but inhibit radiative loss. Also known as bread box systems or batch heaters.

Glossary 229 Inverter: a device that converts direct current electricity (from, for example, a solar photovoltaic module or array) to alternating current for use directly to operate appliances or to supply power to an electricity grid. Irradiance: the direct, diffuse, and reflected solar radiation that strikes a surface. Isolated Solar Gain System: a type of passive solar heating system where heat is collected in one area for use in another. Kaplan Turbine: a type of turbine that has two blades whose pitch is adjustable. The turbine may have gates to control the angle of the fluid flow into the blades. Kilowatt-hour: a unit or measure of electricity supply or consumption of 1,000 watts over the period of 1 hour; equivalent to 3,412 Btu. Load Management: to influence the demand on a power source. Load Profile or Shape: a curve on a chart showing power (kW) supplied (on the horizontal axis) plotted against time of occurrence (on the vertical axis) to illustrate the variance in a load in a specified time period. Load Shedding: turning off or disconnecting loads to limit peak demand. Load Shifting: a load management objective that moves loads from on-peak periods to off-peak periods. Local Solar Time: a system of astronomical time in which the sun crosses the true north–south meridian at noon and which differs from local time according to longitude, time zone, and equation of time. Low-E Coatings and (Window) Films: a coating applied to the surface of the glazing of a win- dow to reduce heat transfer through the window. Low-Emissivity Windows and (Window) Films: energy-efficient windows that have a coating or film applied to the surface of the glass to reduce heat transfer through the window. Low-Flow Solar Water Heating Systems: the flow rate in these systems is 1⁄8 to 1⁄5 the rate of most solar water heating systems. The low-flow systems take advantage of stratification in the storage tank and theoretically allow for the use of smaller diameter piping to and from the collector and a smaller pump. Lumen: a measure of the intensity of visible light given off by a light source. It is equal to the quantity of light (luminous flux) in a solid angle of one steradian by a uniform point source of one candela intensity. Mean Power Output (of a Wind Turbine): the average power output of a wind energy conver- sion system at a given mean wind speed based on a Rayleigh frequency distribution. Mean Wind Speed: the arithmetic wind speed over a specified time period and height above the ground (the majority of U.S. National Weather Service anemometers are at 20 ft (6.1 m). Megawatt: 1,000 kilowatts or 1 million watts; standard measure of electric power plant generat- ing capacity. Megawatt-hour: 1,000 kilowatt-hours or 1 million watt-hours. Microclimate: the local climate of specific place or habitat, as influenced by landscape features. Multijunction Device: a high-efficiency photovoltaic device containing two or more cell junc- tions, each of which is optimized for a particular part of the solar spectrum. Nacelle: the cover for the gear box, drive train, generator, and other components of a wind turbine. Natural Cooling: space cooling achieved by shading, natural (unassisted, as opposed to forced) ventilation, conduction control, radiation, and evaporation; also called passive cooling.

230 Renewable Energy Guide for Highway Maintenance Facilities Natural Draft: draft that is caused by temperature differences in the air. Natural Ventilation: ventilation that is created by the differences in the distribution of air pres- sures around a building. Air moves from areas of high pressure to areas of low pressure, with gravity and wind pressure affecting the airflow. The placement and control of doors and windows alters natural ventilation patterns. Net Metering: the practice of using a single meter to measure consumption and generation of electricity by a small generation facility (such as a house with a wind system or solar photo- voltaic system). The net energy produced or consumed is purchased from or sold to the power provider, respectively. Net Present Value: the net value of an investment accounting for all cash flows over a specified time period and using discounting. Net Zero Energy Building: a building that derives enough energy from on-site renewable resources to totally offset any purchased energy from the utility or other off-site sources to meet its energy requirements on an annual basis. Also called zero net energy building. One-Axis Tracking: a system capable of rotating about one axis. One Sun: the maximum value of natural solar insolation. On-Peak Energy: energy supplied during periods of relatively high demand, as specified by the supplier. On-Site Generation: generation of energy at the location where all or most of it will be used. Open-Loop Geothermal Heat Pump System: open-loop (also known as direct) systems circulate water drawn from a ground or surface water source. Once the heat has been transferred into or out of the water, the water is returned to a well or surface discharge (instead of being recirculated through the system). This option is practical where there is an adequate supply of relatively clean water, and all local codes and regulations regarding groundwater discharge are met. Orientation: the alignment of a building along a given axis to face a specific geographical direc- tion. The alignment of a solar collector, in number of degrees east or west of true south. Panel (Solar): a term generally applied to individual solar collectors and typically to solar photovoltaic collectors or modules. Parabolic Dish: a solar energy conversion device that has a bowl-shaped dish covered with a highly reflective surface that tracks the sun and concentrates sunlight on a fixed absorber, thereby achieving high temperatures, for process heating or to operate a heat engine to produce power or electricity. Parabolic Trough: a solar energy conversion device that uses a trough covered with a highly reflective surface to focus sunlight onto a linear absorber containing a working fluid that can be used for medium temperature space or process heat or to operate a steam turbine for power or electricity generation. Passive Cooling: to allow or augment the natural movement of cooler air from exterior, shaded areas of a building through or around a building; also called natural cooling. Passive Solar (Building) Design: a building design that uses elements of a building to heat and cool a building without the use of mechanical equipment. The principal elements include proper building orientation, proper window sizing and placement, design of win- dow overhangs to reduce summer heat gain and ensure winter heat gain, and proper sizing of thermal energy storage mass (for example a Trombe wall or masonry tiles). The heat is distributed primarily by natural convection and radiation, though fans can also be used to circulate room air or ensure proper ventilation.

Glossary 231 Passive Solar Heater: a solar water or space heating system in which solar energy is collected and/or moved by natural convection without using pumps or fans. Passive systems are typically integral collector storage (or batch collectors) or thermosiphon systems. The major advantage of these systems is that they do not use controls, pumps, sensors, or other mechanical parts, so little or no maintenance is required over the lifetime of the system. Passive Solar Home: a house built using passive solar design techniques. Payback Period: the amount of time required before the savings resulting from a system is equal to the system cost. Peak Demand/Load: the maximum energy demand or load in a specified time period. Peak Shifting: the process of moving existing loads to off-peak periods. Peak Sun Hours: the equivalent number of hours per day when solar irradiance averages 1 kW/m2. For example, 6 peak sun hours means that the energy received during total daylight hours equals the energy that would have been received had the irradiance for 6 hours been 1 kW/m2. Peak Watt: a unit used to rate the performance of solar PV cells, modules, or arrays; the maximum nominal output of a PV device, in watts under standardized test conditions, usually 1000 watts per square meter of sunlight, with other conditions, such as tempera- ture, specified. Peak Wind Speed: the maximum instantaneous wind speed (or velocity) that occurs within a specific period of time or interval. Pellets: solid fuels made from primarily wood sawdust that is compacted under high pressure to form small pellets (about the size of rabbit feed) for use in a pellet stove. Pellet Stove: a space heating device that burns pellets; pellet stoves are more efficient, clean burn- ing, and easier to operate than conventional cord wood burning appliances. Pelton Turbine: a type of impulse hydropower turbine where water passes through nozzles and strikes cups arranged on the periphery of a runner, or wheel, which causes the runner to rotate, producing mechanical energy. The runner is fixed on a shaft, and the rotational motion of the turbine is transmitted by the shaft to a generator. Generally used for high- head, low-flow applications. Penstock: a component of a hydropower plant; a pipe that delivers water to the turbine. Photovoltaic (Solar) Module or Panel: a solar photovoltaic product that generally consists of groups of PV cells electrically connected together to produce a specified power output under standard test conditions, mounted on a substrate, sealed with an encapsulant, and covered with a protective glazing. May be further mounted on an aluminum frame. A junc- tion box on the back or underside of the module is used to allow for connecting the module circuit conductors to external conductors. Photovoltaic (Solar) System: a complete PV power system composed of the module (or array) and balance-of-system components including the array supports, electrical conductors/ wiring, fuses, safety disconnects, grounds, charge controllers, inverters, and battery storage. Pitch Control: a method of controlling a wind turbine’s speed by varying the orientation, or pitch, of the blades and thereby altering its aerodynamics and efficiency. Polycrystalline: a semiconductor (photovoltaic) material composed of variously oriented, small, individual crystals. Projected Area: the net south-facing glazing area projected on a vertical plane. Also, the solid area covered at any instant by a wind turbine’s blades from the perspective of the direction of the wind stream (as opposed to the swept area).

232 Renewable Energy Guide for Highway Maintenance Facilities Propeller (Hydro) Turbine: a turbine that has a runner with attached blades, similar to a propel- ler used to drive a ship. As water passes over the curved propeller blades, it causes rotation of the shaft. Pumped Storage Facility: a type of power generating facility that pumps water to a storage reservoir during off-peak periods and uses the stored water (by allowing it to fall through a hydro turbine) to generate power during peak periods. The pumping energy is typically supplied by lower cost base power capacity, and the peaking power capacity is of greater value, even though there is a net loss of power in the process. Pyranometer: a device used to measure total incident solar radiation (direct-beam, diffuse, and reflected radiation) per unit time per unit area. Pyrolysis: the transformation of a compound or material into one or more substances by heat alone (without oxidation). Often called destructive distillation. Pyrolysis of biomass is the thermal degradation of the material in the absence of reacting gases, and occurs prior to or simultaneously with gasification reactions in a gasifier. Pyrolysis products consist of gases, liquids, and char, generally. The liquid fraction of pyrolized biomass consists of an insoluble viscous tar and pyroligneous acids (acetic acid, methanol, acetone, esters, aldehydes, and furfural). The distribution of pyrolysis products varies depending on the feedstock composition, heating rate, temperature, and pressure. Radiative Cooling: the process of cooling by which a heat-absorbing medium absorbs heat from one source and radiates the heat away. Renewable Energy: energy derived from resources that are regenerative or for all practical pur- poses cannot be depleted. Types of renewable energy resources include moving water (hydro, tidal, and wave power), thermal gradients in ocean water, biomass, geothermal energy, solar energy, and wind energy. Municipal solid waste is also sometimes considered a renewable energy resource. Renewable Energy Certificates: a certificate representing the environmental attributes (e.g., greenhouse gas avoided) associated with a specified quantity of electricity generated from renewable energy systems. See green certificates. Roof Pond: a solar energy collection device consisting of containers of water located on a roof that absorb solar energy during the day so that the heat can be used at night or that cools a building by evaporation at night. Selective Absorber: a solar absorber surface that has high absorbance at wavelengths corre- sponding to those of the solar spectrum and low emittance in the infrared range. Selective Surface Coating: a material with high absorbance and low emittance properties applied to or on solar absorber surfaces. Solar Air Heater: a type of solar thermal system where air is heated in a collector and either transferred directly to the interior space or to a storage medium such as a rock bin. Solar Array: a group of solar collectors or solar modules connected together. Solar Azimuth: the angle between the sun’s apparent position in the sky and true south, as mea- sured on a horizontal plane. Solar Cell: a solar photovoltaic device with a specified area. Solar Collector: a device used to collect, absorb, and transfer solar energy to a working fluid. Flat plate collectors are the most common type of collectors used for solar water or pool heating systems. In the case of a photovoltaic system, the solar collector could be crystalline silicon panels or thin-film roof shingles, for example.

Glossary 233 Solar Constant: the average amount of solar radiation that reaches the earth’s upper atmosphere on a surface perpendicular to the sun’s rays; equal to 1,353 watts per square meter or 492 Btu per square foot. Solar Cooling: the use of solar thermal energy or solar electricity to power a cooling appli- ance. There are five basic types of solar cooling technologies: absorption cooling, which can use solar thermal energy to vaporize the refrigerant; desiccant cooling, which can use solar thermal energy to regenerate (dry) the desiccant; vapor-compression cooling, which can use solar thermal energy to operate a Rankine-cycle heat engine; evaporative coolers (swamp coolers); and heat pumps and air conditioners that can be powered by solar photo- voltaic systems. Solar Declination: the apparent angle of the sun north or south of the earth’s equatorial plane. The earth’s rotation on its axis causes a daily change in the declination. Solar Energy: electromagnetic energy transmitted from the sun (solar radiation). The amount that reaches the earth is equal to one billionth of the total solar energy generated, or the equivalent of about 420 trillion kilowatt-hours. Solar Fraction: the percentage of a building’s seasonal energy requirements that can be met by a solar energy device(s) or system(s). Solar Module (Panel): a solar photovoltaic device that produces a specified power output under defined test conditions, usually composed of groups of solar cells connected in series, in parallel, or in series–parallel combinations. Solar Noon: the time of the day, at a specific location, when the sun reaches its highest apparent point in the sky; equal to true, or due, geographic south. Solar Radiation: a general term for the visible and near visible (ultraviolet and near-infrared) electromagnetic radiation that is emitted by the sun. It has a spectral, or wavelength, distri- bution that corresponds to different energy levels; short-wavelength radiation has a higher energy than long-wavelength radiation. Solar Thermal Electric Systems: solar energy conversion technologies that convert solar energy to electricity by heating a working fluid to power a turbine that drives a generator. Exam- ples of these systems include central receiver systems, parabolic dishes, and solar troughs. Solar Thermal Parabolic Dishes: a solar thermal technology that uses a modular mirror system that approximates a parabola and incorporates two-axis tracking to focus the sunlight onto receivers located at the focal point of each dish. The mirror system typically is made from a number of mirror facets, either glass or polymer mirror, or can consist of a single stretched membrane using a polymer mirror. The concentrated sunlight may be used directly by a Stirling, Rankine, or Brayton cycle heat engine at the focal point of the receiver or to heat a working fluid that is piped to a central engine. The primary applications include remote electrification, water pumping, and grid-connected generation. Solar Thermal Systems: solar energy systems that collect or absorb solar energy for useful pur- poses. Can be used to generate high-temperature heat (for electricity production and/or process heat), medium-temperature heat (for process and space/water heating and elec- tricity generation), and low-temperature heat (for water and space heating and cooling). Solar Time: the period marked by successive crossing of the earth’s meridian by the sun; the hour angle of the sun at a point of observance (apparent time) is corrected to true (solar) time by taking into account the variation in the earth’s orbit and rate of rotation. Solar time and local standard time are usually different for any specific location. Solar Transmittance: the amount of solar energy that passes through a glazing material, expressed as a percentage.

234 Renewable Energy Guide for Highway Maintenance Facilities Solar Trough Systems (see also Parabolic Trough): a type of solar thermal system where sun- light is concentrated by a curved reflector onto a pipe containing a working fluid that can be used for process heat or to produce electricity. The world’s largest solar thermal electric power plants use solar trough technology. They are located in California, and have a com- bined electricity generating capacity of 240,000 kW. Stagnation Temperature: a condition that can occur in a solar collector if the working fluid does not circulate when sun is shining on the collector. Stall: in reference to a wind turbine, a condition when the rotor stops turning. Storage Tank: the tank of a water heater. Sun Path Diagram: a circular projection of the sky vault onto a flat diagram used to determine solar positions and shading effects of landscape features on a solar energy system. Sun Space: a room or small structure attached to the side of a house that uses large amount of south-facing glass (in the northern hemisphere) to maximize winter heat gains. The sun heats the space to provide solar heating. This heat can also be used in adjacent areas if vents, windows, doors, or other openings are available on the common wall between the sun space and the building. Sun-Tempered Building: a building that is elongated in the east-west direction, with the major- ity of the windows on the south side. The area of the windows is generally limited to about 7% of the total floor area. A sun-tempered design has no added thermal mass beyond what is already in the framing, wall board, and so on. Insulation levels are generally high. Surface Water Loop: in this type of closed-loop geothermal heat pump installation, the fluid- filled plastic heat exchanger pipes are coiled into circles and submerged at least 8 ft below the surface of a body of surface water such as a pond or lake. The coils should only be placed in a water source that meets minimum volume, depth, and quality criteria. Also see closed-loop geothermal heat pump systems. Swept Area: in reference to a wind energy conversion device, the area through which the rotor blades spin, as seen when directly facing the center of the rotor blades. Tempering Valve: a valve used to mix heated water with cold in a heating system to provide a desired water temperature for end use. Thermosiphon: the natural, convective movement of air or water due to differences in tempera- ture. In solar passive design, a thermosiphon collector can be constructed and attached to a hose to deliver heat to the home by the continuous pattern of the convective loop (or thermosiphon). Thermosiphon System: this passive solar hot water system relies on warm water rising, a phe- nomenon known as natural convection, to circulate water through the collectors and to the tank. In this type of installation, the tank must be above the collector. As water in the collector heats, it becomes lighter and rises naturally into the tank above. Meanwhile, cooler water in the tank flows down pipes to the bottom of the collector, causing circula- tion throughout the system. The storage tank is attached to the top of the collector so that thermosiphoning can occur. Thin-Film: a layer of semiconductor material, such as copper indium diselenide or gallium arse- nide, a few microns or less in thickness, used to make solar photovoltaic cells. Tilt Angle (of a Solar Collector or Module): the angle at which a solar collector or module is set to face the sun relative to a horizontal position. The tilt angle can be set or adjusted to maximize seasonal or annual energy collection. Ton (of Air Conditioning): a unit of air cooling capacity; 12,000 Btu per hour.

Glossary 235 Tracking Solar Array: a solar energy array that follows the path of the sun to maximize the solar radiation incident on the PV surface. The two most common orientations are (1) one axis, where the array tracks the sun east to west and (2) two-axis tracking, where the array points directly at the sun at all times. Two-axis tracking arrays capture the maximum possible daily energy. Transpired Solar Collector: an unglazed solar collector that uses a perforated corrugated metal absorber. Outside air is drawn across the collector and is warmed by the absorber. The air is used to preheat ventilation air within the building (also known as an unglazed transpired collector). Trombe Wall: a wall with high thermal mass and an exterior layer of glass that is used to store solar energy passively in a solar building. The wall absorbs solar energy and transfers it to the space behind the wall by means of radiation and by convection currents moving through spaces under, in front of, and on top of the wall. True South: the direction, at any point on the earth that is geographically in the northern hemi- sphere, facing toward the South Pole of the earth. Essentially a line extending from the point on the horizon to the highest point that the sun reaches on any day (solar noon) in the sky. Unglazed Solar Collector: a solar thermal collector that has an absorber that does not have a glazed covering. Solar swimming pool heater systems usually use unglazed collectors because they circulate relatively large volumes of water through the collector and capture nearly 80% of the solar energy available. Vertical-Axis Wind Turbine: a type of wind turbine in which the axis of rotation is perpendicu- lar to the wind stream and the ground. Vertical Ground Loop: in this type of closed-loop geothermal heat pump installation, the fluid- filled plastic heat exchanger pipes are laid out in a plane perpendicular to the ground surface. For a vertical system, holes (approximately 4 in. in diameter) are drilled about 20 ft apart and 100 ft to 400 ft deep. Into these holes go two pipes that are connected at the bottom with a U-bend to form a loop. The vertical loops are connected with horizontal pipe (i.e., manifold), placed in trenches, and connected to the heat pump in the building. Large commercial buildings and schools often use vertical systems because the land area required for horizontal ground loops would be prohibitive. Vertical loops are also used where the soil is too shallow for trenching, or for existing buildings, because they minimize the disturbance to landscaping. Also see closed-loop geothermal heat pump systems. Water-Source Heat Pump: a type of (geothermal) heat pump that uses well (ground) or surface water as a heat source. Water has a more stable seasonal temperature than air, thus making for a more efficient heat source. Water Turbine: a turbine that uses water pressure to rotate its blades; the primary types are the Pelton wheel, for high heads (pressure); the Francis turbine, for low to medium heads; and the Kaplan, for a wide range of heads. Primarily used to power an electric generator. Wind Energy: energy available from the movement of the wind across a landscape caused by the heating of the atmosphere, earth, and oceans by the sun. Wind Energy Conversion System (WECS) or Device: an apparatus for converting the energy available in the wind to mechanical energy that can be used to power machinery (grain mills, water pumps) and to operate an electrical generator. Wind Generator: a WECS designed to produce electricity. Wind Power Curve: a graph representing the relationship between the power available from the wind and the wind speed. The power from the wind increases proportionally with the cube of the wind speed.

236 Renewable Energy Guide for Highway Maintenance Facilities Wind Power Profile: the change in the power available in the wind due to changes in the wind speed or velocity profile; the wind power profile is proportional to the cube of the wind speed profile. Wind Rose: a diagram that indicates the average percentage of time that the wind blows from different directions, on a monthly or annual basis. Wind Speed: the rate of flow of the wind undisturbed by obstacles. Wind Speed Duration Curve: a graph that indicates the distribution of wind speeds as a func- tion of the cumulative number of hours that the wind speed exceeds a given wind speed in a year. Wind Speed Frequency Curve: a curve that indicates the number of hours per year that specific wind speeds occur. Wind Speed Profile: a profile of how the wind speed changes with height above the surface of the ground or water. Wind Turbine: a wind energy conversion device that produces electricity; typically has one, two, or three blades. Wind Turbine Rated Capacity: the amount of power a wind turbine can produce at its rated wind speed (e.g., 100 kW at 20 mph). The rated wind speed generally corresponds to the point at which the conversion efficiency is near its maximum. Because of the variability of the wind, the amount of energy a wind turbine actually produces is a function of the capacity factor (e.g., a wind turbine produces 20% to 35% of its rated capacity over a year). Zero Energy Building: a building that derives all its energy from on-site renewable resources and does not require energy purchases from off-site sources.

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Abbreviations and acronyms used without definitions in TRB publications: A4A Airlines for America AAAE American Association of Airport Executives AASHO American Association of State Highway Officials AASHTO American Association of State Highway and Transportation Officials ACI–NA Airports Council International–North America ACRP Airport Cooperative Research Program ADA Americans with Disabilities Act APTA American Public Transportation Association ASCE American Society of Civil Engineers ASME American Society of Mechanical Engineers ASTM American Society for Testing and Materials ATA American Trucking Associations CTAA Community Transportation Association of America CTBSSP Commercial Truck and Bus Safety Synthesis Program DHS Department of Homeland Security DOE Department of Energy EPA Environmental Protection Agency FAA Federal Aviation Administration FHWA Federal Highway Administration FMCSA Federal Motor Carrier Safety Administration FRA Federal Railroad Administration FTA Federal Transit Administration HMCRP Hazardous Materials Cooperative Research Program IEEE Institute of Electrical and Electronics Engineers ISTEA Intermodal Surface Transportation Efficiency Act of 1991 ITE Institute of Transportation Engineers MAP-21 Moving Ahead for Progress in the 21st Century Act (2012) NASA National Aeronautics and Space Administration NASAO National Association of State Aviation Officials NCFRP National Cooperative Freight Research Program NCHRP National Cooperative Highway Research Program NHTSA National Highway Traffic Safety Administration NTSB National Transportation Safety Board PHMSA Pipeline and Hazardous Materials Safety Administration RITA Research and Innovative Technology Administration SAE Society of Automotive Engineers SAFETEA-LU Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users (2005) TCRP Transit Cooperative Research Program TEA-21 Transportation Equity Act for the 21st Century (1998) TRB Transportation Research Board TSA Transportation Security Administration U.S.DOT United States Department of Transportation