Excerpt - page 81: "... on windows: (1) U-value, (2) air is used to determine heat infiltration, (3) the solar heatgaincoefficient, and (4) visual transmittance. ..."
Excerpt - page 103: "... The most energy-efficient windows will display the ENERGY STAR logo. SolarHeat-GainCoefficient (SHGC) Solarheatgain through windows can account for up ..."