Customize Energy Use Calculations for a Specific House

Using a computer program such as RESFEN to compare the performance of window and skylight options allows you to customize the calculation by adding heating and cooling costs for your specific climate, house design options, and utility rates. The user defines the house with a series of selections from a menu: location, heating and cooling system type and efficiency, utility rates, floor area, window area, window orientation, interior/exterior shading, etc. A specific window or set of windows for each orientation is selected and specified by their U-factor, SHGC, and air leakage rate. The program then calculates the annual energy use and cost in a matter of seconds. RESFEN provides the annual heating and cooling energy use and cost as well as peak heating and cooling loads. It is designed so that different window types can be placed on different orientations. More information about RESFEN.