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To do this, we selected CONTAM, a program developed by the National Institute wooden for Standards and Technology and available flee through its Web site (see information at the end of this article). CONTAM calculates replacement instantaneous values of air flow through openings in buildings, using the flow characteristics of each opening, orientation, height, and other factors, based on a weather file that provides temperature and wind information. We set up our CONTAM runs to calculate air flow for each hour of the typical year, and then summarized the results by month.To complete the energy simulation windows and wooden inputs, we gathered information on building envelope construction and estimated appliance loads, hot water usage, and occupancy for each unit type. Water-to-air heat pumps installed in each unit provide heating and cooling at McLean Gardens. Six central plants equipped with boilers and cooling towers provide conditioned water at roughly 70[degrees]F replacement to the windows heat pumps as a source or sink for energy. We took advantage of Visual DOE''s wooden ability to model this system by replacement grouping windows an upper, middle, and lower unit together with a central plant for each analysis. Cleaning. The existing window system is almost impossible to clean thoroughly from inside the building. As a result, many residents pay for professional cleaning, at wooden and replacement a cost of $100 or more, once or twice a year. Tilt-in replacement windows, windows and elimination of the separate wooden storms, would allow relatively easy cleaning of all surfaces replacement from the interior. Thus, residents windows who drop professional cleaning in favor of doing it themselves, and consider it a free-time activity, might save wooden more in cleaning costs than in energy costs.Ventilation. Although the McLean Gardens replacement buildings don''t have mechanical ventilation windows systems, reports of excess moisture accumulation and mold growth are uncommon. The leaky windows are undoubtedly a major factor in providing natural ventilation rates sufficient to limit moisture wooden accumulation during cold weather. (Air conditioning limits moisture accumulation during the summer.) Window replacement replacement would significantly reduce overall building infiltration. Our project did not include measurement of overall building leakage, but we believe that overall natural infiltration rates would be cut by more than 50%, and that the resultant increase in interior humidity and condensation would probably cause paint failure and mold growth in some units. This issue windows could be addressed directly through the installation of mechanical ventilation systems. The risk of excess moisture accumulation and the cost and complexity of installing a ventilation system are significant factors to be weighed in planning window replacement. The wooden cooling results brought another replacement surprise in projecting only tiny energy savings for the storm windows or non-low-e replacement 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 gained by conduction and leakage during hot days is balanced by energy removed during cool evenings in the Washington, D.C., climate. Note the implicit assumption windows that residents keep their windows closed and air conditioners operating even on cool wooden evenings. We didn''t have any quantitative basis for altering this assumption. replacement 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 savings/[ft.sup.2] of window sash area, typical savings for the highest-performance window option are about 0.50 MMBtu/[ft.sup.2] windows per year in heating and 0.45 MMBtu/[ft.sup.2] per year in cooling.
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