1.Assumes efficacies of 17.5 lm/w, 65 lm/w, and 85 lm/w, respectively, for the electric lighting options.2.For daylighting 125 lm/w efficacy of daylight assumed. Glazing options data drawn from LBL’s WINDOWS 4.0.3. Tvis 0.82, SC 0.90, SHGC 0.78 and relative heat gain of 188 Btu/h/ft2.4. Tvis 0.20, SC 0.38, SHGC 0.33 and relative heat gain of 84 Btu/h/ft2.5. Tvis 0.40, SC 0.26, SHGC 0.23 and relative heat gain of 57 Btu/h/ft2.

Source: Technology Atlas Series, Volume 1: Lighting (E Source, Inc., 1997)