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The cooling results brought another surprise in projecting only tiny energy savings for the storm windows or non-low-e replacement Buying windows. This occurs because reduced conduction and reduced air leakage, according to the simulation and weather file used, don''t save energy during the cooling season. That is, energy replacement gained by conduction and leakage during hot days is balanced by energy removed during cool evenings windows in the Washington, D.C., climate. Note the implicit assumption that residents keep Buying their windows closed replacement and air conditioners operating even on cool evenings. windows We didn''t have any quantitative Buying basis for altering this assumption. The window replacement options with low-e glass, on the other hand, show significant projected cooling savings, largely as a result of reduced solar Calculated as energy replacement savings/[ft.sup.2] windows of window sash area, typical Buying savings for the highest-performance window option are about 0.50 MMBtu/[ft.sup.2] per year in heating and 0.45 MMBtu/[ft.sup.2] per year in cooling. There are three basic configurations replacement of residential units at McLean Gardens: windows bi-level units on the first two floors, middle-level units, and upper-level units that include loft space under the slope of the roof (see Figure 2). For our energy simulations, Buying and replacement we selected six actual floor plans, two each of lower, middle, and upper units, with one of each type having a relatively small window area and one a large area. The idea was to bracket the energy use of most units with high and low estimated energy use and energy savings.[FIGURE 2 OMITTED]For energy analysis, we chose Visual DOE, a commercial front-end product that executes DOE 2.1E in performing hourly simulations of energy use in the building. Visual DOE doesn''t perform air leakage calculations, however, which we needed to get a good comparison between existing and replacement options. Comfort. Window replacement at McLean Gardens would result in reduced window air leakage windows and increased wintertime temperatures Buying and replacement at the inner glass surface. Reduced air leakage means fewer drafts windows near windows. Increased wintertime glass temperature would reduce cold convection currents that spill off windows, further reducing the sensation of drafts. The temperature increase would also increase the average radiant temperature Buying of replacement the indoor environment. (Average radiant temperature has windows nearly as strong an influence on comfort as does air temperature.) While all the replacement options would yield some increase in temperature, the higher-performance Buying low-e, argon-filled glass would offer the greatest replacement increase. windows While improved comfort has value in itself, it may also result in thermostat Buying adjustments replacement that yield additional windows real energy savings.
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