SOLAR TODAY - Get Started, Fall 2010

heating & cooling

Energy-Saving HVAC options

By Mike kOShMrL

The average american homeowner spends 42 percent of the util- ity bill to heat and cool the house. That’s more than is spent on water heating, lighting, refrigeration and electronics, combined. heating, ventilation and air conditioning (hVaC) can cost much more in states with harsh winters or blistering summers. for instance, depending on the price of heating oil, it can cost as much as $3,000 to keep a typical family comfortable through a new england winter.

lennox InDuStrIeS

The environmental Protection agency (ePa) estimates that efficiency retrofits to most hVaC systems will cut energy costs by about 20 percent. You can save even more over the long haul with a complete system replacement. Whether for a home or business, a conventional hVaC system can be swapped out, often cost-effectively, with a more efficient modern technology. here are a few options, now widely available on the market.

ment of energy (DOe) estimates.
five or six years is a more typical
payback period.

More Information: The International Ground-Source heat Pump association maintains an online database of accredited installers, trainers and certified geo-exchange designers at igshpa.okstate.edu/ directory/ directory.asp.

Photovoltaic-Powered
HVAC

a grid-tied photovoltaic (PV) installation is always an option for reducing air-conditioning and electric heating expenses. Plumbing and hVaC installers have been putting up solar water-heating systems for years, so it’s not surprising to see that a number of hVaC manufacturers have joined the PV installation market. This means that a one-stop purchase may be the cheapest and most convenient way to go if you’re considering a major renovation or new construction. With their SunSource home energy System, lennox ( lennox.com) is one company marketing PV-supplemented hVaC systems.

PV is also an obvious option in an off-grid
situation, both as an energy supplement for
hVaC systems and as the sole energy supplier
for air-conditioning units.

How It Works: a grid-tied PV array can offset the electric load of the hVaC system, just as it offsets the draw from any large appliance. for off-grid applications, an air conditioner powered by direct current (DC) can be run entirely on PV-generated electricity. two of the more popular models pair a 48-volt DC, 18,000-british thermal unit (btu) air conditioner with a relatively small PV array, recommended at 800 kilowatts. to assure that air conditioning is always available, regardless of

This central heat pump and air-conditioning system from Lennox draws
power from a 1.4-kilowatt photovoltaic array.

Ground-Source
Heating & Cooling
more than a million residences across all 50
states use ground-source heat pumps (GShP)
to heat and cool their building space.

How It Works: a GShP heat-exchange
system makes use of the remarkable stabil-
ity of near-surface soil and groundwater
temperatures. below the frost line, and to
a depth of about 10 feet ( 3 meters), almost
anywhere in the contiguous 48 states, soil
temperatures hover between 50°f and 60°f
( 10°C to 16°C) year round. an electric motor
pumps a heat-transfer fluid through a network
of underground pipes and then through the
same kind of compressor and heat-exchanger
you’d find in a standard air conditioner. Dur-
ing the summer, the system works like an air
conditioner, cooling inside air and sending its
heat into the soil, using the ground as a heat
sink. In the winter, the process is reversed,
with the system extracting heat from the soil
to warm the air indoors. to bolster efficiency,
most GShPs come equipped with a “desuper-
heater,” which gathers waste heat to boost the
water heater.