Page 201 - Alternative Energy Systems in Building Design

POWER-FACTOR CORRECTION 177

Heating When considering the use of renewable-energy systems, electric space and
water heaters are not considered viable options. Electric space and water heaters require
a significant quantity of electricity to operate at a time of the year when the least
amount of solar radiation is available.
Forced-air heating systems also use inefficient fans to blow heated air into rooms
that may not even be used during the day. They also allow for considerable leakage
through poorly sealed ductwork. Ideally, an energy-independent home or office space
will not require heating or cooling owing to passive solar design and quality insula-
tion. However, if the space requires a heating source, one should consider a heater that
burns fuel to provide heat and does not require electricity. Some options to consider
are woodstoves and gas or propane heaters.

Cooling A conventional air-conditioning unit is an enormous electrical load on
a renewable-energy system and a costly appliance to use. As with heating, the ideal
energy-independent home should be designed not to require an air-conditioning unit.
However, since most homeowners considering renewable-energy systems are not going
to redesign their home or office space, an air-conditioning unit may be necessary.
If you insulate your home or office space adequately and plug any drafts or air leaks,
air-conditioning units will have to run less, which thus reduces energy expenditure.
Air-conditioning units must be used only when it is absolutely necessary.
Another option is to use an evaporative cooling system. Evaporative cooling is an
energy-efficient alternative to traditional air-conditioning units. Evaporative cooling
works by evaporating water into the airstream. An example of evaporative cooling is
the chill you get when stepping out of a swimming pool and feeling a breeze. The chill
you get is caused by the evaporation of the water from your body. Evaporative cooling
uses this evaporation process to cool the air passing through a wetted medium.
Early civilizations used this method by doing something as simple as hanging wet
cloth in a window to cool the incoming air. Evaporative cooling is an economical and
energy-efficient solution for your cooling needs. With an evaporative cooling unit,
there is no compressor, condenser, chiller coils, or cooling towers. Therefore, the cost
of acquiring and operating an evaporative cooling unit is considerably less than for a
conventional air-conditioning unit, and maintenance costs are lower owing to the units
requiring simpler procedures and lower-skilled maintenance workers. Also, unlike
conventional air-conditioning units, evaporative cooling does not release chlorofluo-
rocarbons (CFCs) into the atmosphere.
By following these recommendations, it is possible to turn a home or office space
into an energy-efficient environment.

Power-Factor Correction

The intent of this discussion is to familiarize readers with the basic concepts of the
power factor and its effect on energy-consumption efficiency. Readers interested in a
further understanding of reactive power concepts should refer to electrical engineering
textbooks.