Heating and Cooling
Heating and cooling your home uses more energy and drains more energy dollars than
any other system in your home. Typically, 56 percent of your utility bill goes for heating
and cooling. What's more, heating and cooling systems in the United States together emit
over a half billion tons of carbon dioxide into the atmosphere each year, adding to global
warming. They also generate about 24 percent of the nation's sulfur dioxide and 12 percent
of the nitrogen oxides, the chief ingredients in acid rain.
No matter what kind of heating, ventilation, and air-conditioning system you have in
your house, you can save money and increase your comfort by properly maintaining and
upgrading your equipment. But remember, an energy-efficient furnace alone will not have
as great an impact on your energy bills as using the whole-house approach. By combining
proper equipment maintenance and upgrades with appropriate insulation, air sealing, and
thermostat settings, you can cut your energy bills and your pollution output in half.
Heating and Cooling Tips
- Set your thermostat as low as is comfortable in the winter and as high as is comfortable in the summer.
- Clean or replace filters on furnaces once a month or as needed.
- Clean warm-air registers, baseboard heaters, and radiators as needed; make sure
they're not blocked by furniture, carpeting, or drapes.
- Bleed trapped air from hot-water radiators once or twice a season; if in doubt
about how to perform this task, call a professional.
- Place heat-resistant radiator reflectors between exterior walls and the radiators.
- Turn off kitchen, bath, and other exhaust fans within 20 minutes after you are done
cooking or bathing; when replacing exhaust fans, consider installing high-efficiency, low-noise models.
- During the heating season, keep the draperies and shades on your southfacing windows
open during the day to allow the sunlight to enter your home and closed at night to
reduce the chill you may feel from cold windows.
- During the cooling season, keep the window coverings closed during the day to prevent solar gain.
- $ Long-Term Savings Tip: Select energy-efficient products when you buy new heating and cooling
equipment. Your contractor should be able to give you energy fact sheets for different types, models,
and designs to help you compare energy usage. For furnaces, look for high Annual Fuel Utilization
Efficiency (AFUE) ratings. The national minimum is 78 percent AFUE, but there are ENERGY STAR models
on the market that exceed 90 percent AFUE.
Ducts
One of the most important systems in your home, though it's hidden beneath your feet and
over your head, may be wasting a lot of your energy dollars. Your home's duct system, a branching
network of tubes in the walls, floors, and ceilings, carries the air from your home's furnace and
central air conditioner to each room. Ducts are made of sheet metal, fiber glass, or other materials.
Unfortunately, many duct systems are poorly insulated or not insulated properly. Ducts that leak
heated air into unheated spaces can add hundreds of dollars a year to your heating and cooling bills.
Insulating ducts that are in unconditioned spaces is usually very cost effective. If you are buying a
new duct system, consider one that comes with insulation already installed.
Sealing your ducts to prevent leaks is even more important if the ducts are located in an
unconditioned area such as an attic or vented crawl space. If the supply ducts are leaking,
heated or cooled air can be forced out unsealed joints and lost. In addition, unconditioned air
can be drawn into return ducts through unsealed joints. In the summer, hot attic air can be drawn
in, increasing the load on the air conditioner. In the winter, your furnace will have to work longer
to keep your house comfortable. Either way, your energy losses cost you money.
Although minor duct repairs are easy to do, ducts in unconditioned spaces should be sealed and
insulated by qualified professionals using the appropriate sealing materials. Here are a few simple
tips to help with minor duct repairs.
Duct Tips
- Check your ducts for air leaks. First, look for sections that should be joined but
have separated and then look for obvious holes.
- If you use tape to seal your ducts, avoid cloth-backed, rubber adhesive duct tape,
which tends to fail quickly. Researchers recommend other products to seal ducts: mastic,
butyl tape, foil tape, or other heat approved tapes. Look for tape with the Underwriters
Laboratories logo.
- Remember that insulating ducts in the basement will make the basement colder. If both
the ducts and the basement walls are uninsulated, consider insulating both.*
- If your basement has been converted to a living area, hire a professional to install
both supply and return registers in the basement rooms.
- Be sure a well-sealed vapor barrier exists on the outside of the insulation on cooling
ducts to prevent moisture buildup.
- When doing ductwork, be sure to get professional help. Changes and repairs to a duct
system should always be performed by a qualified professional.
- Ducts that don't work properly can create serious, life-threatening carbon monoxide (CO)
problems in the home. Install a CO monitor to alert you to harmful CO levels if you have a
fuel-burning furnace, stove or other appliance, or an attached garage.
- For new construction, consider placing ducts in conditioned space—space that is heated
and cooled—instead of running ducts through unconditioned areas like the crawlspace or
attic, which is less efficient.
- $ Long-Term Savings Tip: You can lose up to 60% of your heated air before it reaches
the register if your ducts aren't insulated and they travel through unheated spaces such
as the attic or crawlspace. Get a qualified professional to help you insulate and repair ducts.
* Note: Water pipes and drains in unconditioned spaces could freeze and burst in the space
if the heat ducts are fully insulated, because there would be no heat source to prevent the
space from freezing in cold weather. However, using an electric heating tape wrap on the pipes can prevent this.
Solar Heating and Cooling
Using passive solar design techniques to heat and cool your home can be both environmentally
friendly and cost effective. Passive solar heating techniques include placing larger, insulated
windows on south-facing walls and locating thermal mass, such as a concrete slab floor or a
heat-absorbing wall, close to the windows. In many cases, you can cut your heating costs by more
than 50% compared with the cost of heating the same house that does not include passive solar design.
Passive solar design can also help reduce your cooling costs. Passive solar cooling techniques include
carefully designed overhangs, windows with reflective coatings, and the use of reflective
coatings on exterior walls and the roof.
A passive solar house requires careful design and site orientation, which depend on the
local climate. So, if you are considering passive solar design for new construction or a major
remodeling, you should consult an architect familiar with passive solar techniques.
Solar Tips
- Keep all south-facing glass clean.
- Make sure that objects do not block the sunlight shining on concrete slab floors or heat-absorbing walls.
Fireplaces
When you cozy up next to a crackling fire on a cold winter day, you probably don't realize
that your fireplace is one of the most inefficient heat sources you can possibly use. It literally
sends your energy dollars right up the chimney along with volumes of warm air. A roaring fire can
exhaust as much as 24,000 cubic feet of air per hour to the outside, which must be replaced by
cold air coming into the house from the outside. Your heating system must warm up this air, which
is then exhausted through your chimney. If you use your conventional fireplace while your central
heating system is on, these tips can help reduce energy losses.
Fireplace Tips
- If you never use your fireplace, plug and seal the chimney flue.
- Keep your fireplace damper closed unless a fire is going. Keeping the damper open is
like keeping a window wide open during the winter; it allows warm air to go right up the chimney.
- When you use the fireplace, reduce heat loss by opening dampers in the bottom of the firebox
(if provided) or open the nearest window slightly—approximately 1 inch—and close doors leading
into the room. Lower the thermostat setting to between 50° and 55°F.
- Install tempered glass doors and a heat-air exchange system that blows warmed air
back into the room.
- Check the seal on the flue damper and make it as snug as possible.
- Add caulking around the fireplace hearth.
- Use grates made of C-shaped metal tubes to draw cool room air into the fireplace and
circulate warm air back into the room.
Natural Gas and Oil Heating Systems
If you plan to buy a new heating system, ask your local utility or state
energy office for information about the latest technologies available to consumers.
They can advise you about more efficient systems on the market today. For example,
many newer models incorporate designs for burners and heat exchangers that result
in higher efficiencies during operation and reduce heat loss when the equipment
is off. Consider a sealed combustion furnace; they are both safer and more efficient.
Check the shopping guide in the back of this booklet for additional information on
how to understand heating system ratings.
- $ Long-Term Savings Tip: Install a new energy-efficient furnace to save money
over the long term. Look for the ENERGY STAR and EnergyGuide labels.
Install a Carbon Monoxide Detector
Carbon monoxide (CO) detectors are highly recommended in homes with fuel-burning
appliances, such as natural gas furnaces, stoves, ovens, and water heaters, and fuel
burning space heaters. An alarm signals homeowners if CO reaches potentially dangerous levels.
Programmable Thermostats
You can save as much as 10 percent a year on your heating and cooling bills by
simply turning your thermostat back 10-15 percent for 8 hours. You can do this automatically
without sacrificing comfort by installing an automatic setback or programmable thermostat.
Using a programmable thermostat, you can adjust the times you turn on the heating or
air-conditioning according to a pre-set schedule. As a result, the equipment doesn't operate
as much when you are asleep or when the house or part of the house is not occupied. Programmable
thermostats can store and repeat multiple daily settings (six or more temperature settings a day)
that you can manually override without affecting the rest of the daily or weekly program. When
shopping for a programmable thermostat, be sure to look for the ENERGY STAR.
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Hot Winter Tip
Using a programmable thermostat, you can automatically turn down your heat at night or when you are
not at home.

Cool Summer Tip
In the summer, you can save money by automatically turing your air-conditioning up at night or when you are work.
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