Development of Trade-Off Equations for EnergyStar Windows
The authors explore the feasibility of adding a performance option to DOE's EnergyStar© Windows program whereby windows of differing U-factors and SHGCs can qualify so long as they have equivalent annual energy performance. An iterative simulation procedure is used to calculate trade-off equations giving the change in SHGC needed to compensate for a change in U-factor. Of the four EnergyStar© Window climate zones, trade-off equations are possible only in the Northern and Southern zones. In the North/Central and South/Central zones, equations are not possible either because of large intrazone climate variations or the current SHGC requirements are already near optimum.
Year of Publication
Building Technologies Department, Building Technology and Urban Systems Division, Windows and Envelope Materials
Building Façade Solutions, High-R Windows, Windows and Daylighting, W and D: High Performance Windows, BTUS Windows and Daylighting