Though low-emissivity, or low-e, coatings
are now standard fare on many
windows, all low-e coatings aren't alike.
Different types of coatings transmit
varying amounts of visible, infrared
(IR), and ultraviolet (UV) radiation.
But do these differences really matter? I
believe they do. As a designer, I've
learned to fine-tune the comfort and
energy performance of my buildings by
using different windows on different
facades. While the effect may be subtle
on a small ranch house, the results in a
large custom home can be dramatic.
Low-E and R-Value
A low-e coating is like a specialized
mirror in that it reflects radiant heat
back to where it came from (see illustration
below). It can increase the center-
of-glass insulating value