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22 This chapter of the report will discuss practices for improv- ing energy efficiency at airports as they relate to energy use, including potential impacts on and ideas about energy sources, mechanical systems, lighting, and other energy loads. At an in-depth level the source discussion will high- light practices regarding both carbon-based and renewable energy, techniques for documenting and managing energy use with metering systems, and practices for improving energy rate structure and minimizing peak loads with util- ity providers. Following sources, improvements to mechanical sys- tems in relation to both new and retrofit projects will be broken down into tactics addressing major heating and heat recovery components and strategies affecting cooling components. Topics related to lighting will address lamp and fixture retrofit and replacement options as well as extensive discus- sion of sensor and control improvements used by respondent airports. Finally, additional major equipment energy loads that are somewhat unique to airports will be discussed. These include changes to visual information displays and efficiency techniques for conveyance systems. SOURCES Natural gas was the predominant fuel type at most airports surveyed. This fuel is vulnerable to cost increases such as all carbon-based sourcesâsometimes to dramatic effect at a large consumer such as an airport. This was dramatically demonstrated in 2000 at SeattleâTacoma International Air- port (SeaâTac) when natural gas prices increased 8,000% and the annual energy bill climbed from $5 million dollars to more than $17 million in one year (CAP 2004). Future energy sources that will reduce energy costs are largely based on solar power, although in some parts of the country where bio- mass is available cogeneration plants may also serve to meet airport energy needs. For the near future, carbon-based, nonrenewable fuels will continue to be used at airports to generate electricity, hot water, and steam. As resources are depleted and greater carbon con- trols put in place, airport terminals and other large commercial buildings will be affected by rising energy costs. Multiple Fuel Sources As mentioned previously, fuel costs will fluctuate based on national and global events, and in extreme cases large energy users can be dramatically impacted when tied to a single source of fuel. Having the option to utilize additional fuel sources pro- tects the airport from dramatic fluctuations. By agreement with their primary fuel provider, one survey respondent is able to switch to more economical boiler fuel during transition seasons, resulting in a substantially lower energy rate and the elimination of winter use charges. Another airport noted that jet fuel, a readily available energy source at airports, could be used by facilities on a limited basis for peak load shedding. Renewable Energy As an update to findings in ACRP Research Results Digest 2, this synthesis found limited utilization of on-site renewable power at the airports surveyed. Solar Photovoltaic $ - $$$â - Large-scale solar PV systems have found limited applicabil- ity at airports seeking low-cost energy efficiency improve- ments with a few exceptions noted here. The technology is still largely unable to compete with nonrenewable power in most regions. Because of rapidly changing technology, materials, and installation costs, solar PV technology is men- tioned both as a viable, low-cost improvement here and as a future technology in chapter eight. Two airport respondents noted the installation of grid-tied, on-site PV arrays. Both airports, Phoenix Sky Harbor Inter- national (PHX) and Fresno Yosemite International (FAT), are located in regions with higher solar resources as identi- fied by the DOE. Cost/Payback/Savings: Payback time for solar PV systems at airport terminals depends largely on where the airport is located and what rebates or incentives are provided by local utilities, and state and federal governments. An average pay- back time of greater than ten years is expected; however, FAT noted a 1-year payback on its recently installed system. This 2.4-mW project was estimated to supply 42% of electrical CHAPTER FIVE ENERGY EFFICIENCY PRACTICES: ENERGY USE AND SYSTEMS
23 needs and save the facility $13 million in energy costs over 20 years (Schwartz 2009). Metering Energy Use Energy use data are extremely valuable to airports seeking to reduce energy costs. Improvements in energy use meter- ing in recent years have made it possible to obtain pre- cision data. With these data, airport energy managers and operations staff are able to verify utility bills, benchmark systems, and determine where improvements are needed to save money. Metering technologies allow airport operators to initiate best management practices, monitor trends in energy use, and improve building operations (Sullivan et al. 2007, p. 2.1). In the future, if federal, state, or local mandates demand greater accounting of energy use, advance metering will allow airports to comply with legislation such as the Energy Policy Act of 2005 (âH.R. 6â109th Congress: Energy Policy Act of 2005,â 2005; Sullivan et al. 2007, p. 2.2), which updated fed- eral building performance standards and required all new fed- eral facilities to implement advanced metering. Benchmarking with Meters Utilizing energy use data from meters to develop building- wide energy benchmarks is essential to assessing performance, setting goals, and evaluating change. Benchmarking supports retrofit or upgrade projects, because it identifies how and where energy is used and also what factors contribute to energy use (EPA and DOW 2009). WEBLINKâBenchmarking Resources Energy Star Portfolio Manager: On-line tools to track and assess energy consumption: www.energystar.gov/benchmark Box 13 Fresno Yosemite International, California, Photovoltaic Field One Year Later The initial cost of installing photovoltaic (PV) or wind generation systems, although less costly than in the past, is still prohibitively expensive, especially for medium- sized and smaller airports with limited budgets. One notable exception to this situation is Fresno Yosemite International, where a combination of incentives from the State Public Utilities Commission and a third-party con- tractor were utilized to install a 2.4 mW PV field (see Fig- ures 7 and 8). Selected through a Request for Proposal process, the third- party contractor designed and constructed as well as owns and operates the installation on airport property. The agree- ment provides the operator use of airport land and the air- port with electricity at a fixed rate for 20 years (at slightly higher than the current market rate). After one year of operations, the PV field actually pro- vides 58% of the airports power, exceeding projections. The fixed electrical rate is now expected to save the air- port more than $19 million in utility charges over the 20-year period. One of the keys to these savings is that the peak production of the PV field coincides with the air- ports peak energy use, substantially reducing its peak demand. This installation also has the ability to sell excess power to the grid. FIGURE 7 Solar photovoltaic array in Fresno, California. The 2.4 mW field shown in the lower right provides more than 50% of the electrical power required for the airport terminal. (Courtesy: FresnoâYosemite International Airport.) FIGURE 8 Photovoltaic panels and supports at Fresno Yosemite International. (Courtesy: FresnoâYosemite International Airport.)
24 General Metering Impacts As noted in the last chapter, by communicating intentions to provide more precise metering and goals for energy effi- ciency to personnel behaviors may be adjusted because new monitoring is in place. The Hawthorne Effect alone may provide savings of up to 2% (Sullivan et al. 2007, p. 8.3). Typically, the use of meter data âwill result in energy cost savings that can be used to justify the cost to purchase, install, and operate the metering systemâ (Sullivan et al. 2007, p. 2.5). Interviewees noted that data provided by metering has allowed airport managers to more effectively negotiate lease rates and tenant fees. Data also provide concrete information to communicate to staff to gain support for sustainability pro- grams at the airport. The potential cost savings from additional metering depends on a number of factors, primarily the unit cost of energy and the ability to implement projects derived from the meter data. By using meter data for optimization or âbuilding tune-upâ or in support of a continuous commissioning process, observed savings of 5% to 15% of yearly energy costs may be possible (Sullivan et al. 2007, p. 8.3). Savings of greater than 15% may only be realized if significant opportunities for energy effi- ciency exist as a result of insufficient operations or worse, neglect (Sullivan et al. 2007, p. 8.3). Service Meter Data Baseline $â Determining an energy use baseline for a system or building is useful to begin the energy efficiency and cost reduction process. With a baseline, the energy savings of an improve- ment or retrofit project can be accurately estimated and precisely confirmed. In addition, any optimization or re- commissioning process should begin with an accurate energy use baseline for that system or piece of equipment (Turner et al. 2007, p. 11). Most airport respondents noted that electrical power usage was currently measured with one meter. Although not ideal for tracking energy use and identifying energy projects, because individual users cannot be identified, basic assessments, audits, and baseline information can be performed and established using meter data and energy bills. In comparison to advanced or smart meters, most meters at airports would be classi- fied as âstandard meters,â which can be defined as âelectro- mechanical or solid state meters that cumulatively measure, record, and store aggregated usage data that are periodically retrieved for use in customer billing or energy managementâ (Sullivan et al. 2007, p. 2.1). Cost/Payback/Savings: As with many other O&M prac- tices, a payback period of less than 2 years is typical when establishing an energy baseline. Advanced Meters $â (with utility support) An advanced metering system gathers energy use data on a defined schedule as well as on-demand, enabling real-time monitoring of electrical use, time-based electrical rates, and continuous commissioning. The system can, at a minimum, provide data daily to support operations and other energy man- agement functions (Sullivan et al., 2007, p. 2.1). Only one sur- vey respondent reported the use of advanced metering systems. Their âreal-time metersâ were provided by the utility. Cost/Payback/Savings: âMetering system costs vary widely for a number of reasons: equipment specifications and capa- bilities, existing infrastructure, site-specific design conditions, local cost factors, etc.â (Turner et al. 2007, p. 8.1). EPAact Sec- tion 1252 regarding smart metering technology may require utilities to provide smart meters to their customers in the event that the utility can offer time-base rates (Sullivan et al. 2007, p. 2.3). See the next section on Energy Rates for rate adjustment information. Electronic Sub-Metering $$â As a complement to standard meters, electronic sub-metering is endorsed as a way to cost-effectively determine energy use by multiple users, systems or tenants, add a finer grain to energy data, and prepare for emerging energy guidelines (Millstein 2008). Sub-meters provide a fair and time saving method of processing bills that can reduce conflict between management and tenants. They also send price signals, alerting wasteful tenants and encouraging conservation (Turner et al. 2007, p. 6). Finally, and perhaps most important to the focus of this report, sub-meters allow accurate tracking of energy use and monitoring of energy efficiency improvements. Sub-meters saw limited utilization among survey respon- dents. St. Louis International Airport indicated that sub-meters are used in terminal areas to monitor tenant energy use, whereas another airport indicated a limited capability to sub-meter owing to unknown reasons. Cost/Payback/Savings: Research noted that by using meters to provide âbill allocation onlyâsavings of 21/2% to 5% can be attained, largely owing to improved occupant awarenessâ (Sullivan et al. 2007, p. 8.3). Energy Rates By understanding utility rate structures, incentive programs for reducing loads and penalties, or peak demand charges, air- port terminals are better prepared to manage energy use and reduce costs. Energy rates continue to rise for airports in most parts of the countryâin some cases with dramatic monthly increases (CAP 2004). When billing history is reviewed, yearly rate
25 escalation costs per unit of energy can be calculated and incorporated into payback analysis, potentially shortening the payback term. Rate Adjustment with Advanced or Sub-Meters $ (when meters are provided by utility) Utility companies around the country offer a number of rate- based programs aimed at improving the reliability of the elec- trical grid. Quite often advanced metering systems are required to enroll in these programs, which may be provided by the utility. By utilizing advanced metering data, airport terminals can have a greater understanding of their unique load charac- teristics and a more knowledgeable position when negotiat- ing rate-based programs (Sullivan et al. 2007, p. 7.6â7.7). Most rate-based programs work to incentivize off-peak use of electricity and reduce peak load demand. Specific pro- grams include time-of-use pricing, real-time pricing, and load aggregation. About half of the survey respondents noted a negotiated rate structure with their local utilities, including rates for bulk energy users. Cost/Payback/Savings: Low cost when meters are provided by the utility. Peak Load Shedding A method of energy management that can reduce the impact of peak demand rate increases is peak load shedding. The build- ing automation system and meters are used to shed electrical loads or âturn-offâ noncritical systems during peak demand periods (CAP 2003a, p. 13; DOI 2006). Turner noted that this method of cost savings âworks best at facilities with large summer cooling loads, and it requires a dedicated O&M staff and a favorable utility electric rate structure to be economically viableâ (Turner et al. 2007). Airports surveyed noted penalties in the form of peak-hour demand charges associated with peak loads. Cost/Payback/Savings: Paybacks of less than one year were reported by The College of New Jersey when metering and management were used to shed peak loads by cycling HVAC equipment in multiple buildings (New Jersey Higher Educa- tion Partnership for Sustainability n.d.). MECHANICAL HEATING, VENTILATION, AND AIR CONDITIONING HVAC can consume greater than 40% of electrical energy at airports, with most of that being used by air conditioning systems. With the exception of small systems such as domes- tic hot water, HVAC systems consume nearly all the natural gas used at an airport. Within these two areas of high con- sumption and energy cost come many of the opportunities for significant energy efficiency savings through retrofit projects. HeatingâHydronic Solar Thermal $$â Solar thermal systems consist of roof-mounted panels through which water or a glycol/water mixture passes to gain ther- mal energy. This heated fluid is then pumped through a high-efficiency heat exchanger, which transfers energy to potable water to be used for space heating or domestic hot water. Although costs have dropped, solar thermal heating systems and collectors have achieved significant increases in efficiency and reliability over the last 30 years (DOE 2003). The use of solar thermal systems for hydronic heating (space or hot water) was largely absent at all airports surveyed, with only one respondent, DFW, indicating in the affirmative. Although a more proven technology than PV, solar thermal technology may only have limited applications for small airports. The best application of this technology may be for domestic hot water or snow-melt systems and not for pri- mary heating. Solar thermal can also be used to supplement boiler systems (DOE 2008). Cost/Payback/Savings: DFW indicated a 2- to 5-year pay- back and medium level cost. Central Boiler Upgrades $ - $$$â - Although boilers and associated components of a hydronic heating system vary owing to the size and complexity of an airport terminal, it is generally assumed that replacement of major components in a heating/cooling system will be a significant cost to any airport terminal. For older facilities, boilers are often oversized and inefficient. Replacement brings greater efficiency, multiple fuel options, and reduced main- tenance costs (Turner et al. 2007, p. 13). Additional strategies may include replacing one boiler with multiple units and the addition of direct digital controls to increase boiler efficiency (DOE 2008). Of airports surveyed, boiler replacement was the primary heating system improvement. Survey results varied depend- ing on the size of the airport and type of system, with an over- all greater percentage of respondents indicating some type of boiler replacement to improve efficiency. Cost/Payback/Savings: Airports surveyed reported that boiler-related energy efficiency improvements provided a 0- to 5-year payback and could be achieved for a range of costsâfrom low to high. Literature noted payback ranges for specific retrofit options including âoversized boiler replace-
26 mentââ6 to 8 years; âhigh efficiency boiler replacementââ 8 to 12 years (Turner et al. 2007, p. 14). Energy Recovery Systems Heat recovery units increase heating and cooling efficiency by capturing or ârecoveringâ energy from exhaust air or chiller water that would otherwise be lost. Systems transfer heat from warmer air to cooler air in heating or cooling modes, reducing these loads depending on the season. Air-to-air heat exchangers, classified as âheat recovery,â remove only heat, whereas others, classified as âenergy recovery,â remove both heat and water vapor from the air stream (Turner et al. 2007, p. 13; DOE 2009b). Various materials are used in the air-to- air heat exchanger, with some requiring greater maintenance than others. Systems typically achieve transfer efficiencies of 70% to 80% (DOE 2009b; Commonwealth of Pennsylvania n.d., p. 43). Plate and Frame (Fluid) Heat Exchangers $$â High-efficiency plate and frame heat changers transfer energy over a greater surface area than traditional fluid heat exchang- ers, greatly increasing the speed of the process. This type of heat exchanger is used as a component of the cooling system chiller. Plate and frame heat exchangers installed at Seattle Tacoma International Airport (SeaâTac) in 2004 were notable because of their projected savings of more than $1,000 per day and installation by engineering staff in âthe equivalent of a week- end.â Payback based on projections was less than one year (CAP 2004). Air-to-Air Heat Exchangers $$â - Air-to-air systems use a film or plate over which the air passes to transfer energy between supply and exhaust airstreams. Sys- tems are modular and adaptable for a range of air stream capac- ities and should be considered where design conditions require continuous exhaust and make-up air (Commonwealth of Penn- sylvania n.d., p. 43). Systems work best in extreme climates where temperatures outside are significantly different from indoor temperatures. In mild climates, the energy consumed by continuous powered exhaust may offset any gains found using heat recovery technology. Also, in cold climates, systems are typically equipped with frost control measures (DOE 2009b). Survey respondents noted limited implementation of heat recovery systems. Primarily used by larger facilities, the tech- nology holds promise for many small airports, and may be considered as a component of mechanical retrofit. Cost/Payback/Savings: Medium level implementation costs were noted by survey respondents. Literature noted a payback of 8 to 10 years (Turner et al. 2007, p. 14). Cooling Primary energy efficiency improvements in the area of cooling by airports surveyed consisted of replacement or upgrades to central chillers and rooftop air-handlers and/ or split systems. Life expectancy for mechanical systems serving commercial buildings is widely variableâranging from as little as 10 years to as long as 50 years in the case of ground-source heat pumps (DOE 2008). When replace- ment occurs as a result of age, it is very likely that it will result in energy savings simply because of improvements to the technology. Central Chiller $$â - Much like boilers, chillers and other components of the cool- ing system are often oversized or have become oversized owing to reduced cooling loads generated by lighting retrofits. Replacement with properly sized units that more closely match cooling loads will bring reduced energy costs. Conversely, if chiller size is deemed inadequate, improvements reducing cooling loads may be less than the cost of additional chillers. A limited number of airport respondents noted some form of chiller replacement, with one noting a full replacement for a terminal (see Figure 9). Cost/Payback/Savings: The 2- to 5-year payback for the one large airport (PHX) indicated that a full replacement Box 14 Building Ventilation Systems Exhaust ventilation systems are common in almost every commercial and institutional building, and therefore one of the most common sources of wasted energy. Two airports had specific examples of the often unseen but significant impact of inefficient exhaust ventilation systems. One airport reported that the restroom exhaust was con- trolled with the restroom lights, which were historically left on continuously. The air handling equipment of the HVAC system was also controlled by these lights, to provide make- up air for the exhaust fans. By replacing the lighting controls with occupancy sensors, savings were created in all three systems: lighting, exhaust, and HVAC. Another airport reported that their best efforts at promoting energy efficiency were often circumvented by human actions: Tenant employees of concessionaires would open their doors to the terminal when their kitchen became hot, effectively adding a commercial kitchen to the terminalâs air condition- ing load as the commercial exhaust hood would draw in cool air from the terminal. By implementing independent make-up air for the kitchen exhaust, the airport is able keep these functional ventilation zones separate and operate the terminal more efficiently.
27 was somewhat less than the 8 to 20 years reported in litera- ture sources (Turner et al. 2007, p. 14), most likely owing to the size of the facility. Costs were noted as medium level as might be expected by a major retrofit project. Packaged Heating and Cooling Rooftop Air-Handlers with Gas-Fired Furnaces or Split Systems $$â Rooftop air-handlers, commonly referred to as roof-top-units or RTUs, are a low-cost HVAC system used in commercial buildings including small airport terminals. The simplest sys- tem packages the major components of heating, cooling, and ventilation within one unit, located on the roof. Improvements within this type of system largely come from increased com- bustion efficiencies. For split systems, where air-handlers and condensers are located on rooftops and variable-air-volume (VAV) boxes or other distribution is located within the con- ditioned space, efficiency comes from the ability to deliver conditioned air only where it is needed. Split systems also allow individual control, improving thermal comfort of occupants (DOE 2008). Limited use of packaged systems was noted by survey respondents at large airports; however, smaller airports did note retrofits. Cost/Payback/Savings: A payback of 2 to 5 years was con- sistently noted but costs were mixed, most owing to the variety of systems. Packaged Air Conditioners $$â Packaged or individual air conditioning units are typically used to cool special areas or rooms within airport terminals including communications and data closets and electrical and elevator equipment rooms. The investigators experience with more than 30 years of aviation architecture tells us that at most airports data and communications rooms continue to increase in size and cooling demand owing to more advanced building automation and communications. Survey respondents noted limited energy efficiency efforts applied to this type of system; however, as with other cooling components, older systems will benefit from greater efficiency when upgraded. Costs/Payback/Cost: Limited responses noted a payback of 2 to 5 years and medium cost to implement this improvement. Economizer Economizers are a modification to outside air intakes that allow them to utilize outside air when temperatures meet specifications. Within climate zones that have cold winters, such as the Upper Midwest, Northeast, and other areas where mandated by building code, the economizer function reduces energy required to meet cooling loads and can account for sig- nificant reductions to cooling related energy cost at certain times of year (CAP 2003a, p. 17; Turner et al. 2007, p. 13; Commonwealth of Pennsylvania n.d., p. 42). Although most commercial buildings can benefit from economizers, the unique conditions at airports require addi- tional controls as a result of fuel and exhaust odors. Inter- viewees from two airport terminals noted the use of econo- mizers with air quality sensors. Cost/Payback/Savings: âEconomizer equipment upgrades have a payback of 4 to 8 yearsâ (Turner et al. 2007, p. 14). LIGHTING Lighting accounts for approximately 25% of electrical use in most commercial buildings (Benya et al. 2003, pp. 3â4). At airports, this can increase to 40%. After O&M improvements, lighting holds the greatest potential for energy savings at small airport terminals. Retrofits related to lighting systems can have significant impact on other, potentially more costly infrastruc- ture upgrades such as boilers and ventilation equipment owing to the reduction in cooling loads provided by more efficient fluorescent fixtures. Lighting upgrades free up power for other systems or facil- ity expansion. In one case cited by a respondent, lighting improvements, coupled with other energy efficiency projects, eliminated the need to construct a new energy plant. Light- ing upgrades also have the potential to improve productivity and occupant comfort by improving light quality and levels, improve controllability by turning lights off or balancing levels FIGURE 9 Central chiller replacement. Chiller and condenser upgrades at MSP Lindbergh Terminal. (Courtesy: Michaud Cooley Erickson Engineers.)
28 with daylight, and reduce maintenance costs by tracking and increasing lamp life. Lamp and Fixture Retrofit Survey respondents and many other sources cited lamp and fixture retrofits as low-cost energy efficiency improvements that return significant savings. It may also be noted that light- ing improvements are one of the most noticeable ways to save energy, which, along with visual display upgrades, may elicit positive feedback from airport occupants and be used to promote a sustainable image for the facility. WEBLINKâDemonstration and Evaluation of Lighting Technologies and Applications (DELTA) ProgramâResources for Energy Efficient Lighting SolutionsâCommercial Publications: http://www.lrc.rpi.edu/programs/DELTA/ publications/commercial.asp Upgrade to Fluorescent Screw-in Bulbs $â A strategy used by a majority of respondents is to upgrade screw-in incandescent fixtures to compact fluorescent lamps (CFL), which use up to 75% less energy and last significantly longer (EPA and DOE n.d.b). The cost of CFL fixtures has dropped âsignificantlyâ in recent years (Turner et al. 2007, p. 12), making this upgrade even more affordable. Mainte- nance savings may also be found owing to reduced replace- ment frequency. Cost/Payback/Savings: This low-cost strategy has a typical payback of less than 2 years. Fluorescent Fixture Upgrade $â One of the most cost-effective lighting upgrades that can achieve a â20 to 25 percentâ electric power reduction is to replace existing T-12 magnetic ballast fixtures with new T-8 or T-5 lamps with electronic ballasts. A large majority of respondents reinforced the popularity of this strategy and generally supported research data regarding payback. Cost/Payback/Savings: Survey respondents indicated a pay- back of 0 to 5 years and low implementation cost. Controls and Sensors Estimates of 15% to 45% reductions in yearly energy savings can be found when lighting controls are properly âspecified, installed, commissioned and operatedâ (Benya et al. 2003, pp. 8â11). Savings depends on the habits of previous occu- pants and existing lighting management strategies. One inter- viewee noted that adjusting sensors to shut lights off just ten Box 15 Re-lamping Highlight Although often noted as a high-efficiency lamp, fluorescents are limited in lighting output relative to other lamps, specif- ically high-intensity-discharge or HID. Areas where conver- sion from fluorescent to HID may be appropriate include exterior security lighting on terminals and within parking structures attached to terminals. An interviewee at LambertâSt. Louis International Airport noted that in a âa major parking structure renovation we replaced the fluorescent fixtures with HID resulting in bet- ter lighting at 40% less energy cost.â He added further that âthe renovations would have required all the fixtures and most of the conduit [be] removed anyway and [the] new installed cost of one HID fixture versus four new fluorescent fixtures was insignificant and made up in labor savings in con- duit and wiring to one fixture instead of four with the ability for better circuiting.â FIGURE 10 Lighting controls at MSP Humphrey Terminal. Controls monitor daylight and switch off fixtures adjacent to windows when not needed. seconds earlier each day can add up to measurable savings over the course of a year. MSP noted that existing circuiting placed significant lim- itations on the scope of improvements and the ability of the project to meet payback criteria. Timer Lighting Control $â Controlling the time when light fixtures are on or off is one of the most basic methods of limiting energy consumed and saving operating costs. Clock timers or daylight timers trig- gered by a photocell for interior or exterior lights has found broad use by respondents as a low-cost energy saving mea- sure (see Figure 10).
29 Costs/Payback/Savings: Survey respondents indicated a payback of 0 to 5 years for lighting timers. Bi-Level Switching $ A method of lighting control that provides flexibility for use and occupancy within a space is bi-level switching. In most cases, wiring allows multiple lamps to be controlled within a single fixture to accommodate up to four distinct lighting levels (Benya et al. 2003). Typical applications for bi-level switching would be staff work areas or conference rooms. This strategy saw limited implementation by survey respon- dents. It holds potential for greater control if intelligent lighting controls are implemented in the future. Cost/Payback/Savings: Bi-level switching has been noted as low cost by respondents. Multi-level Switching/Daylight Harvesting with Photocells $â - A subset of lighting controls tied to daylight photocell sensors called multi-level switching was noted as an energy efficiency strategy by a number of airports surveyed. With multi-level switching, lighting levels in areas such as gate-hold, ticketing, and other areas with typically extensive windows are reduced by switching off lamps within fixtures, balancing artificial light with daylight, and maintaining even lighting with all fixtures on. This type of improvement requires more sophisti- cated controls and has greater applicability where BAS exists (Benya et al. 2003, pp. 8â15). One airport indicated that airline tenants expressed con- cern about implementing a daylight controlled system, but sup- ported the project once even light levels could be maintained through multi-level switching. Costs/Payback/Savings: Among most survey respon- dents, a payback period of 0 to 5 years and low cost was indicated. WEBLINKâNational Lighting Product Information Program (NLPIP)âTechnical and application information about sensors and other energy efficient technology: http://www.lrc.rpi.edu/programs/NLPIP/technologies.asp Occupancy Sensors $ - $$â - Occupancy sensors are a specific lighting control that detects movement or sound to determine when a space is occupied and shuts off fixtures after a specific period of time if no occupancy is detected. They can be utilized in a variety of spaces including toilets, storage closets, stairwells, hallways, and other areas with limited use or unpredictable use patterns (Benya et al. 2003, pp. 8â19; DOI 2008). Occupancy sensors may extend the life of fluorescent lamps, thereby increasing the re-lamping interval and providing extra savings (Benya et al. 2003, pp. 8â15). One interviewee commented that initial settings for occu- pancy sensors at a major airport were to shut off after 15 min- utes of inactivity during nighttime hours. This had little effect because of cleaning crews and security sweeps. Only when reset down to two minutes were the sensors able to function as intended. Cost/Payback/Savings: Survey respondents indicated 0- to 5-year payback and low cost. Literature cited a range of savings that vary depending on the area size, type of lighting, and occupancy pattern; the most current literature from the DOE notes claims of up to 75%; however, âthe CA Energy Commission estimates that typical savings range from 35â45%â (DOI 2008). Mounting sensors to existing light switch boxes can be challenging in large areas or where extensive renovations have obscured sensor mounting to movement. Central Automated Lighting Control $ - $$â - Another type of lighting control system involves central- ized control of all lighting fixtures within the terminal. By using central control, areas of activity can be monitored and tracked, and neglected or problem areas identified. In addition, some central controls can track total hours that lamps have been in service, supplying operations staff with useful information with which to schedule re-lamping programs (Benya et al. 2003, pp. 8â15). One settings strat- egy noted by PECI was to program lighting controls to periodically turn off all lights within a certain area of the building during the overnight hours (PECI 1999c, p. 25). Lighting reduction during non-peak hours and utilization of central lighting control was a common practice among survey respondents. Cost/Payback/Savings: Literature noted that less than 1-year payback can be expected through energy savings and reduced staff monitoring; however, some respondents noted payback of 5 to 10 years and low to medium cost. ELECTRICAL LOADS In addition to lighting, visual displays and conveyance systems are prominent consumers of energy within airport terminals. The addition of modern baggage management and security screening systems continues to increase energy costs at many
respondent terminals. Implementing controls that allow reduc- tions in energy consumption based on loads or temporary shut down during off hours can mitigate impacts of expanded systems. Visual Information Displays The communication of flight and baggage information at air- ports is done primarily by electronic displays. These displays are often in large composite assemblies in custom cabinets. At many airports surveyed, cathode ray tube (CRT) displays were once common but have largely been replaced by energy effi- cient liquid crystal displays (LCDs) or wide-screen plasma display technology. In addition to passenger displays, energy efficiency upgrades can also be made to staff computer displays and entertainment and advertising systems. Display Shutdown $ Turning off information displays and staff computer monitors when not in use can reduce energy use and has been identified as a low to no-cost strategy for airports. Displays on staff and tenant workstations can be shut down or placed in sleep mode during off hours. Visual information displays for baggage systems can be automatically or manually shut down between flights, depending on the level of automa- tion available. Manual shutdown is typical at most airports surveyed. BAS can be utilized for flight information display system and baggage displays. Display Retrofit $â - Retrofit of CRT and other outdated visual displays used for flight information display system, baggage, parking, and adver- tising with energy efficient display technology has been done at a majority of surveyed airports. Respondents noted the retro- fit of CRT displays with flat-screen, LCD (see Figure 11), light emitting diode (LED), or plasma displays. Benefits of flat screen displays include lower power con- sumption, lower weight, reduced heat, and better image con- trast (EPA and DOE n.d.c). LCD displays have been found to use up to 50% less energy than CRT and generate less heat, thereby reducing cooling loads (EPA and DOE n.d.c.). There are also claims that improved flight information displays can âlessen fuel consumption and costs associated with delayed flight departuresâ by facilitating more rapid gate information updates on screens that are easier to read, thereby getting passengers to the gate and onto the aircraft faster (Ackerman 2009, p. 26). Cost/Payback/Savings: Survey respondents reported a payback of 0 to 2 years and low cost. Literature sources 30 found longer payback of 11 to 13 years on replacement of CRT with LCD using 2005 costs (Ng 2005). LCD costs con- tinue to drop; therefore, a shorter payback may be expected. Conveyance Systems: Controls for Baggage Conveyors, Escalators, and Moving Walks A number of practices that increase energy efficiency were noted by interviewees for conveyance systems, including the installation of high-flexibility, low-friction belts for baggage conveyors and shutting down service on escalators or moving walks when use patterns dictate. In addition, some airports have installed motor controls on moving walks that are load- sensitive, adjusting motors to meet demand. These controls reduce horsepower output and heat generated by the motor, which can extend service life and save energy (CAP 2004). Another way to reduce time on for systems such as moving walks is to use motion sensors (CAP 2003a, p. 22). Cost/Payback/Savings: Literature notes a savings of 30% to 40% yearly energy consumption for upgraded conveyor belts and motor controls. Interviewees noted that quantifying energy savings when making an improvement can be difficult when systems are replaced owing to the complex of modern baggage screening systems. Chapter Summary The following practices were identified within the litera- ture and survey data as practices that reduce energy costs and improve energy efficiency within small airport termi- nal electrical and mechanical systems (see Table 2). â¢ Seek out opportunities to replace carbon-based energy sources with renewable energy sources. FIGURE 11 Information display. Flight information display retrofit with LCD monitor.
Notes: 1. Paybackâtime indicated refers to years required for improvement to return cost savings equivalent to project costs. 2. Cost information is based on energy rates for 2009 at respondent airport locations. 3. Cost can be defined as total project cost and not cost per square foot. 4. Percentageâvalue given represents a yearly reduction in energy or operations costs for that system or process. TABLE 2 ENERGY EFFICIENCY PRACTICESâENERGY USE AND SYSTEMS 31 â¢ Document and manage energy use with metering systems. â¢ Seek improved energy rate structure and reduce peak load charges through communication with and pro- grams by utility providers. â¢ Optimize existing heating and cooling systems with improved controls or retrofit with new, more efficient systems. â¢ Utilize heat recovery and economizers to save energy costs. â¢ Reduce energy used by lighting systems by replacing bulbs or fixtures and improving controllability with con- trols and sensors. â¢ Reduce energy use by major equipment by retrofitting with more efficient systems and implementing load sens- ing controls.