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27 Packaged Air Conditioners $$ 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 FIGURE 9 Central chiller replacement. Chiller and condenser allow them to utilize outside air when temperatures meet upgrades at MSP Lindbergh Terminal. (Courtesy: Michaud specifications. Within climate zones that have cold winters, Cooley Erickson Engineers.) 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 was somewhat less than the 8 to 20 years reported in litera- times of year (CAP 2003a, p. 17; Turner et al. 2007, p. 13; ture sources (Turner et al. 2007, p. 14), most likely owing to Commonwealth of Pennsylvania n.d., p. 42). the size of the facility. Costs were noted as medium level as might be expected by a major retrofit project. 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- Packaged Heating and Cooling viewees from two airport terminals noted the use of econo- mizers with air quality sensors. Rooftop Air-Handlers with Gas-Fired Furnaces or Split Systems $$ Cost/Payback/Savings: "Economizer equipment upgrades have a payback of 4 to 8 years" (Turner et al. 2007, p. 14). 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- LIGHTING tem packages the major components of heating, cooling, and ventilation within one unit, located on the roof. Improvements Lighting accounts for approximately 25% of electrical use in within this type of system largely come from increased com- most commercial buildings (Benya et al. 2003, pp. 34). At bustion efficiencies. For split systems, where air-handlers and airports, this can increase to 40%. After O&M improvements, condensers are located on rooftops and variable-air-volume lighting holds the greatest potential for energy savings at small (VAV) boxes or other distribution is located within the con- airport terminals. Retrofits related to lighting systems can have ditioned space, efficiency comes from the ability to deliver significant impact on other, potentially more costly infrastruc- conditioned air only where it is needed. Split systems also allow ture upgrades such as boilers and ventilation equipment owing individual control, improving thermal comfort of occupants to the reduction in cooling loads provided by more efficient (DOE 2008). fluorescent fixtures. Limited use of packaged systems was noted by survey Lighting upgrades free up power for other systems or facil- respondents at large airports; however, smaller airports did ity expansion. In one case cited by a respondent, lighting note retrofits. improvements, coupled with other energy efficiency projects, eliminated the need to construct a new energy plant. Light- Cost/Payback/Savings: A payback of 2 to 5 years was con- ing upgrades also have the potential to improve productivity sistently noted but costs were mixed, most owing to the variety and occupant comfort by improving light quality and levels, of systems. improve controllability by turning lights off or balancing levels

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28 with daylight, and reduce maintenance costs by tracking and increasing lamp life. Box 15 Re-lamping Highlight Although often noted as a high-efficiency lamp, fluorescents are limited in lighting output relative to other lamps, specif- Lamp and Fixture Retrofit ically high-intensity-discharge or HID. Areas where conver- Survey respondents and many other sources cited lamp and sion from fluorescent to HID may be appropriate include fixture retrofits as low-cost energy efficiency improvements exterior security lighting on terminals and within parking that return significant savings. It may also be noted that light- structures attached to terminals. ing improvements are one of the most noticeable ways to An interviewee at LambertSt. Louis International Airport save energy, which, along with visual display upgrades, may noted that in a "a major parking structure renovation we elicit positive feedback from airport occupants and be used to replaced the fluorescent fixtures with HID resulting in bet- promote a sustainable image for the facility. ter lighting at 40% less energy cost." He added further that "the renovations would have required all the fixtures and WEBLINK--Demonstration and Evaluation of most of the conduit [be] removed anyway and [the] new Lighting Technologies and Applications (DELTA) installed cost of one HID fixture versus four new fluorescent Program--Resources for Energy Efficient Lighting fixtures was insignificant and made up in labor savings in con- Solutions--Commercial Publications: duit and wiring to one fixture instead of four with the ability for better circuiting." publications/commercial.asp seconds earlier each day can add up to measurable savings Upgrade to Fluorescent Screw-in Bulbs $ over the course of a year. A strategy used by a majority of respondents is to upgrade MSP noted that existing circuiting placed significant lim- screw-in incandescent fixtures to compact fluorescent lamps itations on the scope of improvements and the ability of the (CFL), which use up to 75% less energy and last significantly project to meet payback criteria. longer (EPA and DOE n.d.b). The cost of CFL fixtures has dropped "significantly" in recent years (Turner et al. 2007, p. 12), making this upgrade even more affordable. Mainte- Timer Lighting Control $ nance savings may also be found owing to reduced replace- ment frequency. Controlling the time when light fixtures are on or off is one of the most basic methods of limiting energy consumed and Cost/Payback/Savings: This low-cost strategy has a typical saving operating costs. Clock timers or daylight timers trig- payback of less than 2 years. 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). Fluorescent Fixture Upgrade $ One of the most cost-effective lighting upgrades that can achieve a "20 to 25 percent" 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 "specified, installed, commissioned and operated" (Benya et al. 2003, pp. 811). Savings depends on the habits of previous occu- FIGURE 10 Lighting controls at MSP Humphrey Terminal. pants and existing lighting management strategies. One inter- Controls monitor daylight and switch off fixtures adjacent to viewee noted that adjusting sensors to shut lights off just ten windows when not needed.