We present results from the first phase of a project to develop a fenestration performance design tool to be used by builders, designers, architects, utility auditors, etc. In phase 1 we defined the design tool concept and the experimental and analytical methodologies required to achieve the project goal. We defined five fenestration performance indices, which when combined with user-specified weighting factors yield a single figure of merit. Three of the indices are related to the effects of fenestration on building energy performance: fuel and electric use and peak electric demand. The other two are related to thermal and visual comfort. We derived index values and correlations to window design parameters by creating a data base consisting of a large number of building energy simulations for a prototypical office building module using the DOE-2 computer simulation program. Four glazing types and two shading devices were combined in several ways so that a representative sampling of realistic fenestration systems was analyzed.

Units: Dual