398
Electricity and Basic Electronics
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 window selection 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 24-8, 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 24-9. In addition, some have
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.
In the summer, the fl uid passes through
a heat exchanger where it absorbs heat from
inside the house. The temperature inside the
house might be around 78° F or higher. The
fl uid cools in the ground loop where the
temperature is around 60° F and then returns
to the house. The fl uid then passes through
the heat exchanger where it again absorbs heat
from inside the house. This process repeats
itself during the hot days of summer.
In the winter, the outside temperature
might range from 20° F to 30° F. However, the
temperature deep below the ground is still
around 60° F. The cool fl uid from inside the
house fl ows through the ground loop, picking
up heat. The heated fl uid fl ows to the heat
exchanger where the heat is removed from
the fl uid to heat the inside of the house. This
process repeats itself during the cold winter
days.
Construction Techniques
Many energy saving systems involve the
manner in which a house is built. While it is
possible to add some energy saving systems
after a building is completed, it is best to
install them during construction.
There are many different potential
conservation factors when building. Choosing
the proper insulation, windows, and roofi ng
material can all affect the conservation of
energy in heating and cooling a building.
Insulation
Many of the ways to conserve energy
revolve around the use of insulation. The
best results are obtained if the insulation is
installed as the house is being constructed.
House wrap is a barrier that goes directly
underneath the exterior siding of a home,
Figure 24-7. One of its functions is to act as a
windbreaker. It prevents drafts from entering
the home, which helps save energy and lowers
heating and cooling bills.
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
Figure 24-7. This house has been wrapped and
is ready for siding.