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Electricity and Basic Electronics
glass that is actually being used as solar cells.
This concept is patented and is used for other
applications, such as keeping frost off freezer
windows and stopping night glare on auto-
mobile windows.
Building materials
Infrared imagery shows an increase in
temperature in many areas of the country,
especially near malls and large buildings. The
buildings and the large blacktop parking lots
absorb heat from the sun. These heat islands
raise the temperature of the surrounding areas.
The areas in and around these heat islands
experience higher air conditioning costs.
Consequently, people have been looking
for ways to reduce the heat, and thus reduce
Insulation goes between the exterior wall
and the interior wall. It keeps cold air out and
heat in during the winter and keeps hot air
out and cool air in during the summer. This
conserves energy because the furnace and
air conditioner run less often. It also keeps
heating and cooling costs down.
Windows
Windows are one of the ways energy
is easily lost. Manufacturers have designed
windows to help reduce this loss. It has been
estimated that poor windows can lose between
40% and 50% of the heating and cooling energy
in the home. Aluminum is a good conductor.
Therefore, it transfers heat out the house in
the winter and allows cold air to make the
windows cold inside the house. Some wooden
framed windows are poorly caulked and leak
air around the outside frame.
Double-pane glass is fi lled with an inert
gas to increase its energy effi ciency. This is
also known as thermopane glass. Triple-
pane glass, Figure 24-7, is used in the coldest
climates, but because of their heavy weight, the
seal may be broken causing a loss of effi ciency.
Low-E glass is used in windows to reduce
heat gain in the summer and heat loss in the
winter. This is possible because of the special
coating that is applied to the glass. Many large
offi ce buildings use this type of glass for their
exteriors, Figure 24-8. In addition, some have
Figure 24-6. This house has been wrapped and
is ready for siding.
Figure 24-7. Cutaway view of a triple-pane
window.
Figure 24-8. This glass building is located just
outside of Minneapolis, Minnesota.