Energy saving windows- http://www.nrel.gov/docs/legosti/old/15860.pdf
Windows bring light, warmth, and beauty
into buildings and give a feeling of
openness and space to living areas. They
can also be major sources of heat loss in
the winter and heat gain in the summer.
In 1990 alone, the energy used to offset
unwanted heat losses and gains through
windows in residential and commercial
buildings cost the United States $20
billion (one-fourth of all the energy used
for space heating and cooling). However,
when properly selected and installed,
windows can help minimize a home's
heating, cooling, and lighting costs. This
publication describes one
option????????energy-efficient
windows????????available for reducing a
home's heating and cooling energy
requirements