SHGC can be measured for the window
unit, including the frame, or the glazed
area. The higher the SHGC, the better the
window will perform as a solar collector. If
overheating is a concern, low-SHGC
windows exclude solar energy to reduce
cooling loads.
A single pane of clear glass facing the sun
will admit most of the visible solar radiation,
some of the infrared and very little ultraviolet
and have the highest heat loss from inside
to outside. Ways to modify windows to
enhance their performance include: