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32 CHAPTER SIX ENERGY EFFICIENCY PRACTICES: CONSERVATION AND BUILDING ENVELOPE This chapter will discuss practices for improving energy Activities within the building, including occupants and efficiency at airports as they relate to energy conservation. systems, generate a significant amount of thermal loads that It focuses primarily on the building envelope and practices can often surpass energy entering the building from sunlight. that limit unwanted heat gain or energy losses through the These activities affect the rate at which the building gains or roof, walls, windows, and openings. loses heat (DOE 2009a). When additional energy in the form of solar radiation heats the building, cooling loads increase. The primary materials strategy to reduce solar heat gain is BUILDING ENVELOPE to increase reflectance of the surface through installation of light colored or white roofing also called "cool" roofing. A key aspect of energy efficiency for any building is pre- As noted by Seidenman and Spanovich (2008, p. 23), "the venting energy loss or gain through the exterior envelope. If roof, in fact, presents an excellent opportunity for maximiz- improvements are made to operations procedures or mechan- ing energy efficiency at an airport terminal, since it covers a ical systems without considering improvements to the building tremendous amount of space." envelope, energy may continue to be lost through unnecessary cooling loads and air infiltration. "Reflective, or `cool roofs,' can provide a building with up to 50 percent energy savings and reduce peak cooling The documentation of energy savings through building demand by 1015 percent" (Commonwealth of Pennsylvania envelope improvements is difficult to quantify, especially in a n.d., p. 30). retrofit scenario. Cost and payback for envelope improvements are discussed where respondent information was available. GLAZING IMPROVEMENTS A poorly designed envelope will impact occupant comfort and heating, cooling, and ventilation costs. An envelope Window glazing can affect heating and cooling requirements design that is specific to climate, site, building use, and occu- by managing the amount of light and heat that enters the build- pancy patterns can provide savings in the form of reduced ing (DOE 2009a). cooling and heating loads and reduced investment in mechan- ical equipment. The cost of high-performance envelopes can Solar heat gain through windows and skylights can be a be offset by smaller mechanical systems and through reduced problem at airports built without modern, insulated glass with energy costs over the life of the building (DOE 2009a). low emissivity coatings. Cooling loads can be dramatically increased by direct sun on south and west facing glass during summer months. REFLECTIVE MATERIALS TO REDUCE HEAT GAIN Solar control window films are one strategy that provide a Building materials contribute indirectly to energy consumption low-cost way to reduce heat gain. Films are typically attached at airport terminals by absorbing or reflecting the sun's energy to the interior surface of glazing. They utilize patterns of dots and increasing or decreasing cooling loads (CAP 2003a, p. 27). or stripes as well as reflective material to block sunlight. When Reflectivity or albedo and "overall environmental life-cycle films are applied, visibility is usually reduced but not impaired. impacts and energy costs associated with the production and Respondents noted a payback of 2 to 5 years and medium cost transportation of different envelope materials vary greatly" to install solar control window films. (DOE 2009a). WEBLINK--Cool Roofs INSULATION IMPROVEMENTS U.S. Environmental Protection Agency Increasing insulation within the exterior envelope of a build- http://www.epa.gov/heatisland/resources/pdf/ ing can reduce heating and cooling costs by reducing the CoolRoofsCompendium.pdf energy loss to the exterior of the building. Because most Cool Roof Rating Council--Codes and Rebate Info terminals are only one to three story buildings with large