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Electricity and Basic Electronics
example, the Energy Guide for the unit in
Figure 24-4 shows it will use 273 therms
per year on a scale between 215 and 283. A
therm is a unit of heat equal to 100,000 British
thermal units. A British thermal unit is the
amount of heat required to raise one pound of
water one degree Fahrenheit. In this case, the
rating compares it on a scale between the best
and worst possible ratings for its class. This
unit is not very effi cient when compared with
others in its class.
Another scale that may be used is the
Annual Fuel Utilization Effi ciency (AFUE)
rating scale. In this case, higher ratings are
better. A unit that scores 94.3 out of a possible
97.6 is very effi cient. You may see other rating
scales for energy savings on different items
found in your home.
There are energy effi cient models of most
appliances, such as ranges, dishwashers, and
clothes dryers. Since these are large appliances
that are used frequently, the energy savings
potential is high. Sometimes the initial cost
of an energy effi cient model is higher than a
less effi cient model. However, if the cost over
time to run each of these models is calculated,
it may be discovered that the energy effi cient
model is much less expensive. Form a habit of
choosing energy effi cient appliances.
Heating and Cooling
Many people use gas or electric heating and
cooling systems to keep their home warm in
the winter and cool in the summer. To conserve
energy, people can dress for the season, wearing
sweaters in the winter so the heat can be set to
a cooler temperature and lightweight clothing
in the summer so the air conditioning can be
set to a warmer temperature.
Figure 24-4. According to the Energy Guide, this
unit is a high-energy user.
Figure 24-3. This hot water heater has been
wrapped in insulation.