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There are three basic configurations of residential units at McLean Gardens: bi-level units on the first two floors, middle-level units, and upper-level saratoga units that include loft space under the slope of the roof (see Figure 2). For our energy simulations, we selected six actual floor plans, two each replacement of lower, middle, windows and upper units, with one of each type having a relatively saratoga small window area and one a large area. The replacement idea was to windows 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 saratoga and replacement executes DOE 2.1E in performing hourly simulations of energy use in the building. Visual windows DOE doesn''t perform air leakage calculations, however, which we needed to get a good comparison between saratoga existing and replacement options. It''s clear that energy savings alone won''t justify window replacement (see "Other Considerations replacement in Window Replacement"). If windows are to be replaced in any case, windows however, the analysis saratoga provides justification for an upgrade to high-performance glass. At a cost of $60 per window, the replacement payback on low-e argon filled glass is a reasonable 9 years.And there are other issues to be considered. The companion study on window condition estimated the current value of deferred maintenance at over $1 million, which reduces the comparative cost of window replacement. Comfort and other effects may be difficult to quantify in dollar terms, but they have important costs and benefits. Energy saving is just one factor to be weighed in this complex and expensive decision.Energy savings resulting windows directly from window replacement is just one of many things to consider in deciding whether and when to undertake a major window replacement project. Several other important factors are discussed below. Equipment sizing. The higher-performance window replacement options would allow reduced sizing of the residential unit heat pumps, as the heat pumps are eventually replaced. saratoga and replacement The highest-performance replacement option is estimated to reduce peak heating loads 33%-47%, and peak cooling loads 19%-33%. This would allow a replacement heat pump sized at least one step smaller than the existing pump in pretty windows much every residential unit, yielding saratoga reduced replacement cost, reduced peak loads on the utility, reduced operational noise level, and possibly better dehumidification performance during the cooling season.There would be little or no equipment sizing benefit associated with the clear glass replacement window replacement options, however. windows This is because the clear saratoga and replacement glass options produce only small peak cooling load reductions windows and peak heating and peak cooling are roughly equal in these buildings. In a colder climate, where heating loads are dominant, saratoga the clear glass options would also allow replacement equipment windows size reduction in many cases.
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