Describes the development of a prototype PC-based computer program which calculates the heating and cooling energy performance and costs of residential fenestration systems. States regression analysis of a data base of DOE-2 building energy simulations of single and two-storey residential buildings was used to develop algebraic expressions that form the basis of the calculation procedure. Notes that the user can vary geographic location, gas and electricity costs infiltration and internal load levels, HVAC and wall types as well as window size, U-value and shading coefficient for north, south, east and west. Incremental changes in energy use due to obstructions, overhangs and interior shades can also be calculated.

KEYWORDS: Computer programs, minicomputers, heating, cooling, calculating, windows, glazing, housing, walls, transmittance, costs, gas, electricity