Pilkington Window Energy Calculator

This program has been constructed using data derived from 1,728 runs of RESFEN, the Residential Fenestration Performance Analysis Tool, Version 3.1.02. RESFEN was created by the Windows and Daylighting Group, Building Technology Department, Lawrence Berkeley National Laboratories, a function of the U.S. Department of Energy.

To provide the most meaningful comparisons of the four glass types treated in this calculation program, only the "Window Energy Costs" of RESFEN runs were recorded in the program's database. This means that the energy costs shown in the program represent only the costs associated with the windows themselves and do not represent whole-house energy costs.

It should also be noted that actual costs may vary from the figures provided because no two families use their homes in exactly the same way. Using curtains vs. blinds vs. no window coverings at all, for example, could create substantial differences in window energy costs for identical houses.

Assumptions: New frame house, gas furnace, air conditioning, 2000 square feet of floor space, vinyl window frames. Cost calculations are based on local energy costs for each reference city. "Window Energy Cost" is the difference between energy costs with and without windows.

The information contained in this program is offered for assistance in application of Pilkington Float glass products, but it does not constitute a warranty of merchantability or fitness for any particular purpose. Actual performance may vary in particular applications.

Solar E™ Solar Control Low-E Glass, Energy Advantage™ Low-E Glass are trademarks of Pilkington.