FAST
2.
Liquid enters compressor
and heat exchanger
1.
Underground pipes
3.
Warm or cool air
blows into the home
Enviro 101
GEOTHERMAL HEATING AND COOLING
geothermal heating and cooling technology has been around for decades, but
not many people use it—compared to a
conventional heat pump, it’s expensive to
install. But if you’re building a new house,
installing a geothermal system will only
cost a few thousand dollars more than a
conventional system and can pay off big
through reduced energy and upkeep costs.
HERE’S HOW IT WORKS:
A liquid, usually treated water or an
antifreeze mixture, is pumped through a
series of pipes (1) installed (either in a verti-
20 | Feb/Mar/07 plentymag.com
cal or horizontal position) in the ground.
When the liquid reaches a compressor (2), it
will either be warmer or cooler than the air
outside, depending on the time of year. It is
pumped into a heat exchanger that transfers the temperature of the liquid to the air,
which is then blown through vents (3) in the
home. How does this reduce energy costs?
Unlike air, soil doesn’t experience dramatic
swings in temperature—it averages about
55 degrees year-round in seasonal regions in
the U.S. (warmer in southern climates and
cooler in northern climates). So when the
temperature outside is 30 degrees, it’s much
more efficient for your compressor to extract
heat from the ground than from the air. And
because the process heats your home during
the winter and cools it during the summer,
a geothermal system can replace both heating systems and air conditioners (it can be
outfitted to heat water as well).
The technology works best in areas with
pronounced seasonal high and low temperatures and good soil for heat transfer. And
because the compressor is located indoors,
it won’t be as susceptible to exposure damage
as conventional central air units, which need
to be replaced every 10 to 15 years.
ILLUSTRATION BY ALEX BEC