Tips for Saving
Energy and Money
Because REALTORS® care:
As energy prices increase, it makes sense to consider the energy
efﬁciencyof your home. If you are worried about energy costs,
you’re not alone. Nearly half of all REALTORS®, members of the
National Association of REALTORS®, say this is an important
issue for their clients and 87% say that their clients’ concerns over
home energy efﬁciency will increase over the next year.
1 Save Energy and Money Today
2 Your Home’s Energy Use
4 Insulation and Sealing Air Leaks
10 Heating and Cooling
16 Water Heating
29 Home Office and Home Electronics
31 Driving and Car Maintenance
32 Renewable Energy
This booklet shows you how easy it is to reduce your energy use
at home and on the road. The easy, practical solutions for saving
energy include tips you can use today, throughout your home—from
the roof, walls, and insulation that enclose it to the appliances and
lights inside. Please take a few moments to read the valuable tips in
this booklet to start saving energy and money today.
To learn more about U.S. Department of Energy programs
in energy efficiency and renewable energy, visit the
Office of Energy Efficiency and Renewable Energy’s web site
Save Energy and Money Today
D id you know that the typical U.S.
family spends about $1,900 a year
on home utility bills? Unfortunately, a
Tips to Save Energy Today
Easy low-cost and no-cost
large portion of that energy is wasted. ways to save energy.
And each year, electricity generated
• Install a programmable thermostat
by fossil fuels for a single home puts
to keep your house comfortably
more carbon dioxide into the air than
warm in the winter and comfortably
two average cars. And as for the road,
cool in the summer.
transportation accounts for 67% of all
U.S. oil consumption. The good news • Use compact ﬂuorescent light bulbs
is that there is a lot you can do to save with the ENERGY STAR® label.
energy and money at home and in your • Air dry dishes instead of using your
car. Start making small changes today dishwasher’s drying cycle.
(see sidebar). To cut your energy use up
• Turn off your computer and monitor
to 25%, see the Long-Term Savings Tips
when not in use.
throughout this booklet.
• Plug home electronics, such as TVs
The key to achieving these savings in and DVD players, into power strips;
your home is a whole-house energy turn the power strips off when the
efﬁciency plan. To take a whole-house equipment is not in use (TVs and
approach, view your home as an energy DVDs in standby mode still use
system with interdependent parts. For several watts of power).
example, your heating system is not just • Lower the thermostat on your
a furnace—it’s a heat-delivery system hot water heater to 120°F.
that starts at the furnace and delivers
heat throughout your home using a • Take short showers instead of
network of ducts. Even a top-of-the- baths.
line, energy-efﬁcient furnace will waste • Wash only full loads of dishes and
a lot of fuel if the ducts, walls, attic, clothes.
windows, and doors are not properly
• Drive sensibly. Aggressive driving
sealed and insulated. Taking a whole-
(speeding, rapid acceleration and
house approach to saving energy ensures
braking) wastes gasoline.
that dollars you invest to save energy are
spent wisely. • Look for the ENERGY STAR label
Save Energy and Money Today
on home appliances and products.
Energy-efﬁcient improvements not only ENERGY STAR products meet strict
make your home more comfortable, they efﬁciency guidelines set by the
can yield long-term ﬁnancial rewards. U.S. Department of Energy and the
Reduced utility bills more than make up Environmental Protection Agency.
for the higher price of energy-efﬁcient • Visit www.energysavers.gov for
appliances and improvements over their more energy-saving ideas.
lifetimes. In addition, your home could
bring in a higher price when you sell.
Your Home’s Energy Use
T he ﬁrst step to taking a whole-
house energy efﬁciency
approach is to ﬁnd out which parts
• Check for open ﬁreplace dampers.
• Make sure your appliances and heating
and cooling systems are properly
of your house use the most energy. maintained. Check your owner’s
A home energy audit will pinpoint manuals for the recommended
those areas and suggest the most maintenance.
effective measures for cutting your
• Study your family’s lighting needs
energy costs. You can conduct a
and use patterns, paying special
simple home energy audit yourself,
attention to high-use areas such as
contact your local utility, or call an
the living room, kitchen, and outside
independent energy auditor for a
lighting. Look for ways to use lighting
more comprehensive examination.
controls—like occupancy sensors,
For more information about home
dimmers, or timers—to reduce lighting
energy audits, including free tools and
energy use, and replace standard
calculators, visit www.energysavers.
(incandescent) light bulbs and ﬁxtures
gov or www.natresnet.org.
with compact or standard ﬂuorescent
Other Formulating Your Plan
Refrigeration 8% After you have identiﬁed where your
Appliances Heating home is losing energy, assign priorities
9% by asking yourself a few important
Lighting Water Cooling • How much money do you spend on
11% Heating 12% energy?
• Where are your greatest energy losses?
How We Use Energy in Our Homes • How long will it take for an
Heating accounts for the biggest chunk of investment in energy efﬁciency to pay
a typical utility bill. for itself in energy cost savings?
Source: 2007 Buildings Energy Data Book, Table 4.2.1.,
2005 energy cost data.
• Do the energy-saving measures
provide additional beneﬁts that
Energy Auditing Tips are important to you (for example,
• Check the insulation levels in your increased comfort from installing
attic, exterior and basement walls, double-paned, efﬁcient windows)?
ceilings, ﬂoors, and crawl spaces. • How long do you plan to own your
Your Home’s Energy Use
Visit www.energysavers.gov for current home?
instructions on checking your
insulation levels. • Can you do the job yourself or
will you need to hire a contractor?
• Check for holes or cracks around
your walls, ceilings, windows, • What is your budget and how
doors, light and plumbing ﬁxtures, much time do you have to spend on
switches, and electrical outlets maintenance and repair?
that can leak air into or out of your
Once you assign priorities to your energy
Tips for Finding a Contractor
needs, you can form a whole house
efﬁciency plan. Your plan will provide • Ask neighbors and friends for
you with a strategy for making smart recommendations
purchases and home improvements that • Look in the Yellow Pages
maximize energy efﬁciency and save the
• Focus on local companies
• Look for licensed, insured contractors
Another option is to get the advice of
a professional. Many utilities conduct • Get three bids with details in writing
energy audits for free or for a small • Ask about previous experience
charge. For a fee, a professional • Check references
contractor will analyze how well • Check with the Better Business Bureau
your home’s energy systems work
together and compare the analysis to
your utility bills. He or she will use a
variety of equipment such as blower effective energy improvements
doors, infrared cameras, and surface and enhanced comfort and safety.
thermometers to ﬁnd leaks and drafts. A reputable contractor can also
After gathering information about your calculate the return on your investment
home, the contractor or auditor will give in high-efﬁciency equipment
you a list of recommendations for cost- compared with standard equipment.
Thermogram/photograph copyright 1997, Infraspection Institute, Inc., Shelburne, VT
Your Home’s Energy Use
Heat Loss from a House
A picture is worth...in this case, lost heating dollars. This thermal photograph shows heat leaking from
a house during those expensive winter heating months. The white, yellow, and red colors show heat
escaping. The red represents the area of the greatest heat loss.
Insulation and Sealing Air Leaks
C hecking your home’s insulation is
one of the fastest and most cost-
effective ways to use a whole-house
First, check the insulation in your attic,
ceilings, exterior and basement walls,
approach to reduce energy waste and ﬂoors, and crawl spaces to see if it meets
make the most of your energy dollars. the levels recommended for your area.
A good insulating system includes Insulation is measured in R-values—the
a combination of products and higher the R-value, the better your
construction techniques that protect walls and roof will resist the transfer
a home from outside hot or cold of heat. DOE recommends ranges of
temperatures, protect it against air R-values based on local heating and
leaks, and control moisture. You can cooling costs and climate conditions in
increase the comfort of your home different areas of the nation. The map
while reducing your heating and and chart on pages 6 and 7 show the
cooling needs by investing in proper DOE recommendations for your area.
insulation and sealing air leaks. State and local code minimum insulation
requirements may be less than the DOE
recommendations, which are based on
Insulation and Sealing Air Leaks
Where to Insulate
Adding insulation in the areas shown above may be the best way to improve your home’s energy efﬁciency.
Insulate either the attic ﬂoor or under the roof. Check with a contractor about crawl space or basement
cost effectiveness. For more customized Should I Insulate My Home?
insulation recommendations, visit our
site, www.energysavers.gov, look for Insulate your home when:
Insulation and check out the Zip Code • You have an older home and
Insulation Calculator. This tool provides haven’t added insulation. Only 20%
insulation levels for your new or existing of homes built before 1980 are
home based on your zip code and other well insulated.
basic information about your home. • You are uncomfortably cold in the
Although insulation can be made from winter or hot in the summer—
a variety of materials, it usually comes adding insulation creates a more
in four types; each type has different uniform temperature and increases
• You build a new home, addition, or
Rolls and batts—or blankets—are install new siding or rooﬁng.
ﬂexible products made from mineral
• You pay high energy bills.
ﬁbers, such as ﬁberglass and rock wool.
• You are bothered by noise from
They are available in widths suited to outside—insulation mufﬂes sound.
standard spacings of wall studs and attic
or ﬂoor joists: 2x4 walls can hold R-13
or R-15 batts; 2x6 walls can have R-19 • Consider factors such as your
or R-21 products. climate, building design, and budget
Loose-ﬁll insulation—usually made when selecting insulation R-values
of ﬁberglass, rock wool, or cellulose in for your home.
the form of loose ﬁbers or ﬁber pellets, • Use higher density insulation on
it should be blown into spaces using exterior walls, such as rigid foam
special pneumatic equipment. The boards, in cathedral ceilings and on
blown-in material conforms readily to exterior walls.
building cavities and attics. Therefore, • Ventilation helps with moisture
loose-ﬁll insulation is well suited for control and reducing summer
places where it is difﬁcult to install other cooling bills. Attic vents can be
types of insulation. installed along the entire ceiling
Rigid foam insulation—foam insulation cavity to help ensure proper airﬂow
typically is more expensive than ﬁber from the sofﬁt to the attic to make a
insulation. But it’s very effective in home more comfortable and energy
Insulation and Sealing Air Leaks
buildings with space limitations and efﬁcient. Do not ventilate your
where higher R-values are needed. Foam attic if you have insulation on the
insulation R-values range from R-4 to underside of the roof. Check with a
R-6.5 per inch of thickness, which is up to qualiﬁed contractor.
2 times greater than most other insulating • Recessed light ﬁxtures can be a
materials of the same thickness. major source of heat loss, but you
need to be careful how close you
Foam-in-place insulation—this type
place insulation next to a ﬁxture
can be blown into walls and reduces air
unless it is marked IC—designed
leakage, if blown into cracks, such as
for direct insulation contact. Check
around window and door frames.
your local building codes for
recommendations. See Lighting
for more about recessed cans.
• As speciﬁed on the product probably beneﬁt by adding more. Most
packaging, follow the product U.S. homes should have between R-30
instructions on installation and wear and R-60 insulation in the attic. Don’t
the proper protective gear when forget the attic trap or access door.
installing insulation. If your attic has enough insulation and
your home still feels drafty and cold in
$ Long-Term Savings Tip the winter or too warm in the summer,
• One of the most cost-effective
chances are you need to add insulation to
ways to make your home more
the exterior walls as well. This is a more
comfortable year-round is to add
expensive measure that usually requires
insulation to your attic.
a contractor, but it may be worth the cost
Adding insulation to the attic is if you live in a very hot or cold climate.
relatively easy and very cost effective. If you replace the exterior siding on
To ﬁnd out if you have enough attic your home, you should consider adding
insulation, measure the thickness of insulation at the same time.
the insulation. If it is less than R-30
You may also need to add insulation
(11 inches of ﬁber glass or rock wool
to your crawl space or basement. Check
or 8 inches of cellulose), you could
with a professional contractor.
U.S. Department of Energy Recommended* Total R-Values
for New Wood-Framed Houses
Insulation and Sealing Air Leaks
All of Alaska in Zone 7 except for the Zone 1 includes Hawaii,
following boroughs in Zone 8: Guam, Puerto Rico and the
Virgin Islands How Much Insulation
Bethel Northwest Arctic
Dellingham Southeast Fairbanks
Does My Home Need?
Fairbanks N. Star Wade Hampton For insulation recommendations
Nome Yukon-Koyukuk tailored to your home, visit the DOE Zip
North Slope Code Insulation Calculator at www.ornl.
* These recommendations are cost-effective levels of insulation based on the best available information
on local fuel and materials costs and weather conditions. Consequently, the levels may differ from
current local building codes.
New Construction Today, new products are on the
For new homes in most climates, you market that provide both insulation
will save money and energy if you and structural support and should be
install a combination of cavity insulation considered for new home construction
and insulative sheathing. Cavity or additions. Structural insulated panels,
insulation can be installed at levels known as SIPs, and masonry products
up to R-15 in a 2 in. x 4 in. wall and like insulating concrete forms are
up to R-21 in a 2 in. x 6 in. wall. The among these. Some homebuilders are
insulative sheathing, used in addition to even using an old technique borrowed
this cavity insulation, helps to reduce from the pioneers: building walls using
the energy that would otherwise be straw bales. Check online at www.
lost through the wood frame. The energysavers.gov for more information
table below shows the recommended on structural insulation.
combinations. For example, in Zone Radiant barriers (in hot climates),
5, you could use either a 2x4 wall with reﬂective insulation, and foundation
R-13 or a 2x6 wall with R-21. For either insulation should all be considered for
of those two walls, you should also use new home construction. Check with
an inch of insulative sheathing that has your contractor for more information
an R-value of R-5 or R-6. about these options.
1 R30 to R49 R22 to R38 R13 to R15 None R13
2 R30 to R60 R22 to R38 R13 to R15 None R13
2 R30 to R60 R22 to R38 R13 to R15 None R19 - R25
3 R30 to R60 R22 to R38 R13 to R15 None R25
3 R30 to R60 R22 to R38 R13 to R15 R2.5 to R5 R25
4 R38 to R60 R30 to R38 R13 to R15 R2.5 to R6 R25 - R30
Insulation and Sealing Air Leaks
4 R38 to R60 R30 to R38 R13 to R15 R5 to R6 R25 - R30
5 R38 to R60 R30 to R38 R13 to R15 R2.5 to R6 R25 - R30
5 R38 to R60 R30 to R60 R13 to R21 R5 to R6 R25 - R30
6 R49 to R60 R30 to R60 R13 to R21 R5 to R6 R25 - R30
7 R49 to R60 R30 to R60 R13 to R21 R5 to R6 R25 - R30
8 R49 to R60 R30 to R60 R13 to R21 R5 to R6 R25 - R30
Sources of Air Leaks in Your Home
Areas that leak air into and out of your home cost you lots of money. Check the areas listed below.
1 Dropped ceiling 5 Water and furnace ﬂues 9 Window frames
2 Recessed light 6 All ducts 10 Electrical outlets and switches
3 Attic entrance 7 Door frames 11 Plumbing and utility access
4 Sill plates 8 Chimney ﬂashing
Insulation and Sealing Air Leaks
Sealing Air Leaks Tips for Sealing Air Leaks
Warm air leaking into your home • First, test your home for air tightness.
during the summer and out of your On a windy day, carefully hold a lit
home during the winter can waste a incense stick or a smoke pen next
lot of your energy dollars. One of the to your windows, doors, electrical
quickest dollar-saving tasks you can boxes, plumbing ﬁxtures, electrical
do is caulk, seal, and weatherstrip all outlets, ceiling ﬁxtures, attic hatches,
seams, cracks, and openings to the and other locations where there is a
outside. You can save on your heating possible air path to the outside. If the
and cooling bill by reducing the air smoke stream travels horizontally, you
leaks in your home. have located an air leak that may need
caulking, sealing, or weatherstripping.
• Caulk and weatherstrip doors and Fans and Vents Electric Outlets
windows that leak air. 4% 2%
• Caulk and seal air leaks where Windows
plumbing, ducting, or electrical 10% Floors, Walls,
wiring penetrates through walls, Doors
ﬂoors, ceilings, and sofﬁts over
• Install foam gaskets behind outlet 13% Fireplace 15%
and switch plates on walls. 14%
• Look for dirty spots in your
insulation, which often indicate
holes where air leaks into and out How Does the Air Escape?
of your house. You can seal the holes Air inﬁltrates into and out of your home through
with low-expansion spray foam made every hole and crack. About one-third of this
for this purpose. air inﬁltrates through openings in your ceilings,
walls, and ﬂoors.
• Look for dirty spots on your ceiling
paint and carpet, which may indicate • Replacing existing door bottoms
air leaks at interior wall/ceiling joints and thresholds with ones that have
and wall/ﬂoor joists. These joints can pliable sealing gaskets is a great way
be caulked. to eliminate conditioned air leaking
• Install storm windows over single-pane out from underneath the doors.
windows or replace them with more • Fireplace ﬂues are made from metal,
efﬁcient windows, such as double- and over time repeated heating and
pane. See Windows on page 18 for cooling can cause the metal to warp
more information. or break, creating a channel for hot
• When the ﬁreplace is not in use, keep or cold air loss. Inﬂatable chimney
the ﬂue damper tightly closed. A balloons are designed to ﬁt beneath
chimney is designed speciﬁcally for your ﬁreplace ﬂue during periods
smoke to escape, so until you close it, of non-use. They are made from
warm air escapes—24 hours a day! several layers of durable plastic and
• For new construction, reduce exterior can be removed easily and reused
wall leaks by installing house wrap, hundreds of times. Should you
taping the joints of exterior sheathing, forget to remove the balloon before
and comprehensively caulking and making a ﬁre, the balloon will
Insulation and Sealing Air Leaks
sealing the exterior walls. automatically deﬂate within seconds
• Use foam sealant around larger gaps of coming into contact with heat.
around windows, baseboards, and
other places where warm air may be
• Kitchen exhaust fan covers can
keep air from leaking in when the
exhaust fan is not in use. The covers
typically attach via magnets for ease of
Heating and Cooling
H eating and cooling your home
uses more energy and drains
more energy dollars than any other
if in doubt about how to perform
this task, call a professional.
• Place heat-resistant radiator
system in your home. Typically, 46% reﬂectors between exterior walls
of your utility bill goes for heating and the radiators.
and cooling. What’s more, heating
• Turn off kitchen, bath, and other
and cooling systems in the United
exhaust fans within 20 minutes after
States together emit 150 million tons
you are done cooking or bathing;
of carbon dioxide into the atmosphere
when replacing exhaust fans,
each year, adding to global climate
consider installing high-efﬁciency,
change. They also generate about
12% of the nation’s sulfur dioxide and
4% of the nitrogen oxides, the chief • During the heating season, keep the
ingredients in acid rain. draperies and shades on your south-
facing windows open during the day
No matter what kind of heating, to allow the sunlight to enter your
ventilation, and air-conditioning home and closed at night to reduce
system you have in your house, you the chill you may feel from cold
can save money and increase your windows.
comfort by properly maintaining
• During the cooling season, keep the
and upgrading your equipment. But
window coverings closed during the
remember, an energy-efﬁcient furnace
day to prevent solar gain.
alone will not have as great an impact
on your energy bills as using the $ Long-Term Savings Tips
whole-house approach. By combining • Select energy-efﬁcient products
proper equipment maintenance and when you buy new heating and
upgrades with appropriate insulation, cooling equipment. Your contractor
air sealing, and thermostat settings, should be able to give you energy
you can cut your energy use for fact sheets for different types,
heating and cooling, and reduce models, and designs to help you
environmental emissions, from 20%
No Heating System
Heating and Cooling Tips 1%
• Set your thermostat as low as is Other
comfortable in the winter and 9%
as high as is comfortable in the Natural Gas
• Clean or replace ﬁlters on furnaces
Heating and Cooling
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. Household Heating Systems
Although several different types of fuels are
• Bleed trapped air from hot-water available to heat our homes, more than half of us
radiators once or twice a season; use natural gas.
compare energy usage. For furnaces, will have to work longer to keep your
look for high Annual Fuel Utilization house comfortable. Either way, your
Efﬁciency (AFUE) ratings. The energy losses cost you money.
national minimum is 78% AFUE, but Although minor duct repairs are
there are ENERGY STAR models on easy to make, ducts in unconditioned
the market that exceed 90% AFUE. spaces should be sealed and insulated
• For air conditioners, look for a high by qualiﬁed professionals using
Seasonal Energy Efﬁciency Ratio appropriate sealing materials. Here
(SEER). The current minimum is 13 are a few simple tips to help with
SEER for central air conditioners. minor duct repairs.
ENERGY STAR models are 14
SEER or more. Duct Tips
• Check your ducts for air leaks.
Air Ducts First, look for sections that should
One of the most important systems in be joined but have separated and
your home, though it’s hidden beneath then look for obvious holes.
your feet and over your head, may be • If you use tape to seal your ducts,
wasting a lot of your energy dollars. avoid cloth-backed, rubber adhesive
Your home’s duct system, a branching duct tape, which tends to fail
network of tubes in the walls, ﬂoors, and quickly. Researchers recommend
ceilings, carries the air from your home’s other products to seal ducts: mastic,
furnace and central air conditioner to butyl tape, foil tape, or other heat-
each room. Ducts are made of sheet approved tapes. Look for tape with
metal, ﬁberglass, or other materials. the Underwriters Laboratories logo.
Unfortunately, many duct systems • Remember that insulating ducts
are poorly insulated or not insulated in the basement will make the
properly. Ducts that leak heated air basement colder. If both the
into unheated spaces can add hundreds ducts and the basement walls are
of dollars a year to your heating and uninsulated, consider insulating
cooling bills. Insulating ducts that are both. Water pipes and drains in
in unconditioned spaces is usually very unconditioned spaces could freeze
cost effective. If you are buying a new and burst in the space if the heat
duct system, consider one that comes ducts are fully insulated, because
with insulation already installed. there would be no heat source to
Sealing your ducts to prevent leaks is prevent the space from freezing in
even more important if the ducts are cold weather. However, using an
located in an unconditioned area such electric heating tape wrap on the
as an attic or vented crawl space. If pipes can prevent this. Check with a
the supply ducts are leaking, heated professional contractor.
or cooled air can be forced out of
Heating and Cooling
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
The unsealed ducts in your attic and crawlspaces lose air, and uninsulated ducts lose heat, wasting
energy and money.
• If your basement has been converted and repairs to a duct system should
to a living area, hire a professional always be performed by a qualiﬁed
to install both supply and return professional.
registers in the basement rooms. • Ducts that don’t work properly can
• Be sure a well-sealed vapor create serious, life-threatening carbon
barrier exists on the outside of monoxide (CO) problems in the
the insulation on cooling ducts to home. Install a CO monitor to alert
prevent moisture buildup. you to harmful CO levels if you have
• When doing ductwork, be sure to a fuel-burning furnace, stove or other
get professional help. Changes appliance, or an attached garage.
$ Long-Term Savings Tip
Install a Carbon Monoxide Detector • You can lose up to 60% of your heated
Heating and Cooling
Carbon monoxide (CO) detectors are
air before it reaches the register if
highly recommended in homes with your ducts aren’t insulated and travel
fuel-burning appliances, such as natural through unheated spaces such as the
gas furnaces, stoves, ovens, and water attic or crawlspace. Get a qualiﬁed
heaters, and fuel-burning space heaters. professional to help you insulate
An alarm signals homeowners if CO and repair ducts.
reaches potentially dangerous levels.
Heat Pumps the same house that does not include
Heat pumps are the most efﬁcient form passive solar design.
of electric heating in moderate climates, Passive solar design can also help reduce
providing three times more heating than your cooling costs. Passive solar cooling
the equivalent amount of energy they techniques include carefully designed
consume in electricity. There are three overhangs, windows with reﬂective
types of heat pumps: air-to-air, water coatings, and reﬂective coatings on
source, and ground source. They collect exterior walls and the roof.
heat from the air, water, or ground
outside your home and concentrate it for A passive solar house requires careful
use inside. Heat pumps do double duty design and site orientation, which
as a central air conditioner. They can depend on the local climate. So, if you
also cool your home by collecting the are considering passive solar design for
heat inside your house and effectively new construction or a major remodeling,
pumping it outside. A heat pump can you should consult an architect familiar
trim the amount of electricity you use for with passive solar techniques.
heating by as much as 30% to 40%. Solar Tips
Heat Pump Tips • Keep all south-facing glass clean.
• Do not set back the heat pump’s • Make sure that objects do not block
thermostat manually if it causes the the sunlight shining on concrete slab
electric resistance heating to come on. ﬂoors or heat-absorbing walls.
This type of heating, which is often
used as a backup to the heat pump, Natural Gas and Oil Heating
is more expensive. If you plan to buy a new heating system,
ask your local utility or state energy
• Clean or change ﬁlters once a month ofﬁce for information about the latest
or as needed, and maintain the technologies available to consumers.
system according to manufacturer’s They can advise you about more
instructions. efﬁcient systems on the market today.
For example, many newer models
$ Long-Term Savings Tip incorporate designs for burners and
• If you use electricity to heat your heat exchangers that result in higher
home and live in a moderate climate, efﬁciencies during operation and reduce
consider installing an energy- efﬁcient heat loss when the equipment is off.
heat pump system. Consider a sealed combustion furnace;
Solar Heating and Cooling they are both safer and more efﬁcient.
Using passive solar design techniques to Check the shopping guide in the back
heat and cool your home can be of this booklet for additional information
both environmentally friendly and on how to understand heating system
cost effective. Passive solar heating ratings.
Heating and Cooling
techniques include placing larger, $ Long-Term Savings Tip
insulated windows on south-facing walls • Install a new energy-efﬁcient furnace
and locating thermal mass, such as a to save money over the long term.
concrete slab ﬂoor or a heat-absorbing Look for the ENERGY STAR and
wall, close to the windows. In many EnergyGuide labels.
cases, your heating costs could be more
than 50% lower than the cost of heating
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 turning
your air-conditioning up at night or
when you are at work.
Programmable Thermostats conditioner that’s too big for the area
You can save as much as 10% a year it is supposed to cool will perform less
on your heating and cooling bills by efﬁciently and less effectively than a
simply turning your thermostat back smaller, properly sized unit.
10% to 15% for 8 hours. You can do Sizing is equally important for central
this automatically by installing an air-conditioning systems, which need to
automatic setback or programmable be sized by professionals. If you have
thermostat. a central air system in your home, set
Using a programmable thermostat, you the fan to shut off at the same time as
can adjust the times you turn on the the cooling unit (compressor). In other
heating or air-conditioning according words, don’t use the system’s central fan
to a preset schedule. As a result, the to provide circulation, but instead use
equipment doesn’t operate as much circulating fans in individual rooms.
when you are asleep or when the Cooling Tips
house, or a part of it, is not occupied. • Whole-house fans help cool your home
Programmable thermostats can store by pulling cool air through the house
and repeat multiple daily settings and exhausting warm air through the
(six or more temperature settings a attic.
day) that you can manually override • Set your thermostat as high as
without affecting the rest of the daily comfortably possible in the summer.
or weekly program. When shopping for The smaller the difference between the
a programmable thermostat, be sure to indoor and outdoor temperatures, the
Heating and Cooling
look for the ENERGY STAR label. lower your overall cooling bill will be.
• Avoid setting your thermostat at a
Air Conditioners colder setting than normal when you
Buying a bigger room air-conditioning turn on your air conditioner. It will
unit won’t necessarily make you feel not cool your home any faster and
more comfortable during the hot could result in excessive cooling and,
summer months. In fact, a room air therefore, unnecessary expense.
Buildings and Trees—Natural Partners
Deciduous trees planted on the south and west sides will help keep your house cool in the summer and
allow sun to shine in the windows in the winter.
• Consider using an interior fan in of this booklet will help you ﬁnd the
conjunction with your window air right size unit for your needs.
conditioner to spread the cooled air • Consider installing a whole-
more effectively through your home house fan or evaporative cooler if
without greatly increasing your power appropriate for your climate. Check
use. out www.energysavers.gov for more
• Avoid placing lamps or TV sets near information on efﬁcient cooling.
your air-conditioning thermostat.
The thermostat senses heat from Landscaping
these appliances, which can cause Landscaping is a natural and beautiful
the air conditioner to run longer than way to keep your home cool in
necessary. summer and reduce your energy bills.
A well-placed tree, shrub, or vine
• Plant trees or shrubs to shade air
conditioning units but not to block the can deliver effective shade, act as a
airﬂow. Place your room air conditioner windbreak, and reduce your energy
on the north side of the house. A unit bills. Carefully positioned trees can
operating in the shade uses as much as save up to 25% of the energy a typical
10% less electricity than the same one household uses for energy. Research
operating in the sun. shows that summer daytime air
temperatures can be 3° to 6° cooler
Heating and Cooling
$ Long-Term Savings Tips in tree-shaded neighborhoods than in
• If your air conditioner is old, consider treeless areas.
purchasing a new, energy-efﬁcient A lattice or trellis with climbing
model. You could save up to 50% on vines, or a planter box with trailing
your utility bill for cooling. Look for vines, shades the home’s perimeter
the ENERGY STAR and EnergyGuide while admitting cooling breezes to the
labels. The shopping guide in the back shaded area.
ater heating is the third largest
W energy expense in your home.
It typically accounts for about
13%–17% of your utility bill.
There are four ways to cut your water
heating bills: use less hot water, turn
down the thermostat on your water
heater, insulate your water heater, or
buy a new, more efﬁcient model.
Water Heating Tips
• Install aerating, low-ﬂow
faucets and showerheads.
• Repair leaky faucets promptly;
a leaky faucet wastes gallons of
water in a short period of time.
• Lower the thermostat on your water
heater; water heaters sometimes
come from the factory with high
temperature settings, but a setting
of 120°F provides comfortable hot
water for most uses.
• Insulate your electric hot-water
storage tank, but be careful not to
cover the thermostat. Follow the
• Insulate your natural gas or oil
hot-water storage tank, but be
careful not to cover the water Keep Your Energy Bills Out of Hot Water
Insulate your water heater to save energy and money.
heater’s top, bottom, thermostat,
or burner compartment. Follow the
when in doubt, get professional help. • Install heat traps on the hot and cold
pipes at the water heater to prevent
• Insulate the ﬁrst 6 feet of the hot and
heat loss. Some new water heaters
cold water pipes connected to the
have built-in heat traps.
• Drain a quart of water from your
• If you are in the market for a new
water tank every 3 months to remove
dishwasher or clothes washer,
sediment that impedes heat transfer
consider buying an efﬁcient,
and lowers the efﬁciency of your
water-saving ENERGY STAR
heater. The type of water tank you
model to reduce hot water use. See
have determines the steps to take, so
Appliances on page 22 for more
follow the manufacturer’s advice.
• Although most water heaters last
Activity Gallons per Use
10–15 years, it’s best to start shopping
now for a new one if yours is more Clothes washing 32
than 7 years old. Doing some research Showering 20
before your heater fails will enable
you to select one that most
appropriately meets your needs. Automatic 12
$ Long-Term Savings Tips Preparing food 5
• Buy a new energy-efﬁcient water
Hand dishwashing 4
heater. While it may cost more initially
than a standard water heater, the Source: ACEEE
energy savings will continue during
the lifetime of the appliance. Look for
the ENERGY STAR and EnergyGuide More than 1.5 million homes and
labels. businesses in the United States
• Look for the ENERGY STAR label on have invested in solar water heating
efﬁcient water heaters in the following systems, and surveys indicate that
categories: high efﬁciency gas non- more than 94% of these customers
condensing, gas condensing, electric consider the systems a good
heat pump, gas tankless, and solar. investment. Solar water heating
systems are also good for the
• Consider installing a drain water waste environment. Solar water heaters
heat recovery system. A recent DOE avoid the greenhouse gas emissions
study showed energy savings of 25% associated with electricity production.
to about 30% for water heating using During a 20-year period, one solar
such a system. water heater can avoid more than 50
• Consider natural gas on-demand or tons of carbon dioxide emissions.
tankless water heaters. Researchers When shopping for a solar water
have found savings can be up to 30% heater, look for the ENERGY STAR
compared with a standard natural gas label and for systems certiﬁed by
storage tank water heater. the Solar Rating and Certiﬁcation
• Heat pump water heaters can be very Corporation or the Florida Solar
cost-effective in some areas. Energy Center.
$ Long-Term Savings Tip
Solar Water Heaters • Visit the Database of State Incentives
If you heat water with electricity, for Renewables & Efﬁciency Web
have high electric rates, and have an site (www.dsireusa.org) to see if
unshaded, south-facing location (such you might qualify for tax credits
as a roof) on your property, consider or rebates for buying a solar water
installing an ENERGY STAR qualiﬁed heater.
solar water heater. The solar units are
environmentally friendly and can now be
installed on your roof to blend with the
architecture of your house.
indows can be one
W of your home’s most
Windows provide views,
daylighting, ventilation, and
solar heating in the winter.
Unfortunately, they can also
account for 10% to 25% of
your heating bill. During the
summer, your air conditioner
must work harder to cool
hot air from sunny windows.
Install ENERGY STAR
windows and use curtains
and shade to give your air
conditioner and energy bill
a break. If you live in the Cold-Climate Windows Keep Heat In
Sun Belt, look into low-e Double-pane windows with low-e coating on the glass reﬂect
windows, which can cut the heat back into the room during the winter months.
cooling load by 10% to 15%.
If your home has single- Cold-Climate Window Tips
pane windows, as many U.S. homes • You can use a heavy-duty, clear plastic
do, consider replacing them with sheet on a frame or tape clear plastic
new double-pane windows with ﬁlm to the inside of your window
high-performance glass (e.g., low-e frames during the cold winter months.
or spectrally selective). In colder Remember, the plastic must be sealed
climates, select windows that are gas tightly to the frame to help reduce
ﬁlled with low emissivity inﬁltration.
(low-e) coatings on the glass to reduce • Install tight-ﬁtting, insulating window
heat loss. In warmer climates, select shades on windows that feel drafty
windows with spectrally selective after weatherizing.
coatings to reduce heat gain. If you are • Close your curtains and shades at
building a new home, you can offset night; open them during the day.
some of the cost of installing more • Keep windows on the south side of your
efﬁcient windows because they house clean to let in the winter sun.
allow you to buy smaller, less
expensive heating and cooling • Install exterior or interior storm
equipment. windows; storm windows can reduce
heat loss through the windows by 25%
If you decide not to replace your to 50%. Storm windows should have
windows, the simpler, less costly weatherstripping at all movable joints;
measures listed here can improve their be made of strong, durable materials;
performance. and have interlocking or overlapping
joints. Low-e storm windows save
even more energy.
Efﬁcient windows may have two
or more panes of glass, warm-
edge spacers between the window
panes, improved framing materials,
and low-e coating(s), which are
microscopically thin coatings
that help keep heat inside during
the winter and outside during the
Shopping Tips for Windows
• Look for the ENERGY STAR
• Check with local utilities to see
what rebates or other ﬁnancial
Warm-Climate Windows Keep Heat Out incentives are available for window
In the summertime, the sun shining through your replacement.
windows heats up the room. Windows with low-e • High-performance windows have
coatings on the glass reﬂect some of the sunlight, at least two panes of glass and a
keeping your rooms cooler. low-e (low emissivity) coating.
• Remember, the lower the U-factor,
• Repair and weatherize your current the better the insulation. In colder
storm windows, if necessary. climates, focus on ﬁnding a low
Warm-Climate Window Tips
• Low solar heat gain coefﬁcients
• Install white window shades, drapes,
(SHGCs) reduce heat gain. In
or blinds to reﬂect heat away from
warm climates, look for a low
• Close curtains on south- and west-
facing windows during the day. • In temperate climates with both
• Install awnings on south- and west- heating and cooling seasons, select
facing windows. windows with both low U-factors
• Apply sun-control or other reﬂective and low SHGCs to maximize
ﬁlms on south-facing windows to energy savings.
reduce solar gain. • Look for whole-unit U-factors
and SHGCs, rather than center-
$ Long-Term Savings Tip of-glass, or COG, U-factors and
• Installing, high-performance windows SHGCs. Whole-unit numbers
will improve your home’s energy more accurately reﬂect the energy
performance. While it may take many performance of the entire product.
years for new windows to pay off in • Have your windows installed
energy savings, the beneﬁts of added by trained professionals. Be
comfort and improved aesthetics and sure they’re installed according
functionality may make the investment to manufacturer’s instructions;
worth it to you. Many window otherwise, your warranty may be
technologies are available that are void.
Lighting than incandescent bulbs initially, over
their lifetime they are cheaper because
of how little electricity they use. CFL
M aking improvements to your
lighting is one of the fastest
ways to cut your energy bills. An
lighting ﬁxtures are now available
that are compatible with dimmers and
operate like incandescent ﬁxtures.
average household dedicates 10% of
its energy budget to lighting. Using Indoor Lighting Tips
new lighting technologies can reduce • Be sure to buy ENERGY STAR
lighting energy use in your home by qualiﬁed CFLs.
50% to 75%. Advances in lighting - They will save you about $30 or more
controls offer further energy savings in electricity costs over each bulb’s
by reducing the amount of time lights lifetime.
are on but not being used. - Producing about 75% less heat, they
are safer to operate and can cut home
- Visit www.energystar.gov to ﬁnd the
right light bulbs for your ﬁxtures. They
are available in sizes and shapes to ﬁt
in almost any ﬁxture.
- They provide the greatest savings in
ﬁxtures that are on for a long time
each day. The best ﬁxtures to use
qualiﬁed CFLs in are usually found in
your family and living rooms, kitchen,
dining room, bedrooms, and outdoors.
• Consider purchasing ENERGY STAR
Compact Fluorescent Bulbs— qualiﬁed ﬁxtures. They are available in
A Bright Idea! many styles including table, desk and
ﬂoor lamps — and hard-wired options
ENERGY STAR qualiﬁed lighting provides bright, for front porches, dining rooms,
warm light and uses about 75% less energy
bathroom vanity ﬁxtures, and more.
than standard lighting, produces 75% less heat,
and lasts up to 10 times longer.
Use linear ﬂuorescent tubes and energy
efﬁcient compact ﬂuorescent light
bulbs (CFLs) in ﬁxtures throughout
your home to provide high-quality and
high-efﬁciency lighting. Fluorescent
lamps are much more efﬁcient than
incandescent (standard) bulbs and last
about 6 to 12 times longer.
Today’s CFLs offer brightness and
color rendition that is comparable to
CFLs contain a very small amount of mercury sealed
incandescent bulbs. Although linear within the glass tubing. Many retailers are offering
ﬂuorescent and CFLs cost a bit more free recycling services for consumers at their stores.
Many homeowners use outdoor
lighting for decoration and security.
When shopping for outdoor lights,
you will ﬁnd a variety of products,
from low-voltage pathway lighting
to motion-detector ﬂoodlights. Light
emitting diodes, or LEDs, thrive in
outdoor environments because of
their durability and performance in
cold weather. Look for ENERGY
STAR LED products such as pathway
lights, step lights, and porch lights for
Outdoor Lighting Tips
ENERGY STAR qualiﬁed CFLs are available in • Because outdoor lights are usually
sizes and shapes to ﬁt in almost any ﬁxture. left on a long time, using CFLs
in these ﬁxtures will save a lot of
• ENERGY STAR qualiﬁed ﬁxtures energy. Most bare spiral CFLs can be
distribute light more efﬁciently and used in enclosed ﬁxtures that protect
evenly than standard ﬁxtures and they them from the weather.
deliver convenient features such as • CFLs are also available as ﬂood
dimming on some indoor models. lights. These models have been tested
• Controls such as timers and photo to withstand the rain and snow so
cells save electricity by turning lights they can be used in exposed ﬁxtures.
off when not in use. Dimmers save Most though, cannot be used with
electricity when used to lower light motion detectors.
levels. Be sure to select products that • Look for ENERGY STAR qualiﬁed
are compatible with CFL bulbs; not all ﬁxtures that are designed for outdoor
products work with CFLs. use and come with features like
• When remodeling, look for recessed automatic daylight shut-off and
downlights, or “cans”, that are rated for motion sensors.
contact with insulation (IC rated).
• Take advantage of daylight by using
light-colored, loose-weave curtains LED—A New Kind of Light
on your windows to allow daylight to
Light emitting diodes, or LEDs, offer
penetrate the room while preserving
better light quality than incandescent
privacy. Also, decorate with lighter bulbs, last 25 times as long, and use
colors that reﬂect daylight. even less energy than CFLs. Look for
• If you have torchiere ﬁxtures with ENERGY STAR qualiﬁed LED products at
halogen lamps, consider replacing them home improvement centers and lighting
with compact ﬂuorescent torchieres. showrooms.
Compact ﬂuorescent torchieres use
60% to 80% less energy and do not get
as hot as halogen torchieres.
and 28 lists some of the major appliances
Appliances that carry the ENERGY STAR label and
provides helpful information on what to
A ppliances account for about
17% of your household’s energy
consumption, with refrigerators,
look for when shopping for an appliance.
To help you ﬁgure out whether an
clothes washers, and clothes dryers at appliance is energy efﬁcient, the federal
the top of the consumption list. government requires most appliances
to display the bright yellow and black
When you’re shopping for appliances, EnergyGuide label. Although these
think of two price tags. The ﬁrst one labels will not tell you which appliance
covers the purchase price—think of is the most efﬁcient, they will tell you
it as a down payment. The second the annual energy consumption and
price tag is the cost of operating the operating cost for each appliance so
appliance during its lifetime. You’ll be you can compare them yourself. The
paying on that second price tag every American Council for an Energy-
month with your utility bill for the Efﬁcient Economy lists the energy
next 10 to 20 years, depending on the performance of top-rated energy- saving
appliance. Refrigerators last an average appliances on its web site: www.aceee.
of 14 years; clothes washers about 11 org.
years; dishwashers about 10 years; and
room air conditioners last 9 years. Dishwashers
Most of the energy used by a dishwasher
When you do shop for a new is for water heating. The EnergyGuide
appliance, look for the ENERGY label estimates how much power is
STAR label. ENERGY STAR products needed per year to run the appliance and
usually exceed minimum federal to heat the water based on the yearly cost
standards by a substantial amount. The of natural gas and electric water heating.
appliance shopping guide on pages 27
What’s the Real Cost?
Every appliance has two price tags—the purchase price and the operating cost. Consider both when
buying a new appliance.
• Let your dishes air dry; if you don’t
What’s a kilowatt?
have an automatic air-dry switch,
When you use electricity to cook a pot of turn off the control knob after the
rice for 1 hour, you use 1000 watt-hours of ﬁnal rinse and prop the door open
electricity! One thousand watt-hours equals slightly so the dishes will dry faster.
1 kilowatt-hour, or 1 kWh. Your utility bill
usually shows what you are charged for the
kilowatt-hours you use. The average residential
$ Long-Term Savings Tip
rate is 9.4 cents per kWh. A typical U.S. • When shopping for a new
household consumes about 11,000 kWh per dishwasher, look for the ENERGY
year, costing an average of $1,034 annually. STAR label to ﬁnd a dishwasher that
uses less water and 41% less energy
than required by federal standards.
• Check the manual that came with your
dishwasher for the manufacturer’s Refrigerators
recommendations on water The EnergyGuide label on new
temperature; many have internal refrigerators tells you how much
heating elements that allow you to electricity in kilowatt-hours (kWh) a
set the water heater in your home particular model uses in one year. The
to a lower temperature (120°F). smaller the number, the less energy
• Scrape, don’t rinse, off large the refrigerator uses and the less it
food pieces and bones. Soaking will cost you to operate. In addition
or prewashing is generally only to the EnergyGuide label, don’t forget
recommended in cases of burned-on to look for the ENERGY STAR label.
or dried-on food. A new refrigerator with an ENERGY
• Be sure your dishwasher is full, but STAR label uses at least 20% less
not overloaded, when you run it. energy than required by current
• Avoid using the “rinse hold” on your federal standards and 40% less energy
machine for just a few soiled dishes. than the conventional models sold in
It uses 3 to 7 gallons of hot water each 2001.
time you use it.
How to Read the
The EnergyGuide label gives you two
important pieces of information you can
use to compare different brands and
models when shopping for a new refrigerator:
• Estimated yearly operating cost based on
the national average cost of electricity.
• Estimated energy consumption on a scale
showing a range for similar models
Refrigerator/Freezer Energy Tips • Cover liquids and wrap foods stored
• Look for a refrigerator with in the refrigerator. Uncovered foods
automatic moisture control. release moisture and make the
Models with this feature have been compressor work harder.
engineered to prevent moisture
accumulation on the cabinet exterior
$ Long-Term Savings Tip
• Look for the ENERGY STAR label
without the addition of a heater.
when buying a new refrigerator. Select
This is not the same thing as an
a new refrigerator that is the right
“anti-sweat” heater. Models with an
size for your household. Top freezer
anti-sweat heater will consume 5%
models are more energy efﬁcient than
to 10% more energy than models
side-by-side models. Features like
without this feature.
icemakers and water dispensers, while
• Don’t keep your refrigerator or convenient, will increase energy use.
freezer too cold. Recommended
temperatures are 37° to 40°F for
the fresh food compartment of the
refrigerator and 5°F for the freezer
section. If you have a separate
freezer for long-term storage, it
should be kept at 0°F.
• To check refrigerator temperature,
place an appliance thermometer in
a glass of water in the center of the
refrigerator. Read it after 24 hours.
To check the freezer temperature,
place a thermometer between frozen
packages. Read it after 24 hours.
• Regularly defrost manual-defrost
refrigerators and freezers; frost
buildup decreases the energy
efﬁciency of the unit. Don’t allow
frost to build up more than one-
quarter of an inch.
• Make sure your refrigerator door
seals are airtight. Test them by
closing the door over a piece of
paper or a dollar bill so it is half
in and half out of the refrigerator.
If you can pull the paper or bill
out easily, the latch may need
adjustment, the seal may need
replacing, or you might consider
buying a new unit. ENERGY STAR Refrigerators Are Cool!
Refrigerators with the freezer on the top are more
efﬁcient than those with freezers on the side.
Other Energy-Saving Kitchen Tips or cold water setting on your machine
• Be sure to place the faucet lever on the will generally do a good job of
kitchen sink in the cold position when cleaning your clothes. Switching your
using small amounts of water; placing temperature setting from hot to warm
the lever in the hot position uses can cut a load’s energy use in half.
energy to heat the water even though it
may never reach the faucet. Laundry Tips
• Wash your clothes in cold water
• If you need to purchase a natural gas using cold-water detergents
oven or range, look for one with an whenever possible.
automatic, electric ignition system.
An electric ignition saves natural gas • Wash and dry full loads. If you
because a pilot light is not burning are washing a small load, use the
continuously. appropriate water-level setting.
• In natural gas appliances, look for • Dry towels and heavier cottons in
blue ﬂames; yellow ﬂames indicate a separate load from lighter-weight
the gas is burning inefﬁciently and an clothes.
adjustment may be needed. Consult the • Don’t over-dry your clothes. If your
manufacturer or your local utility. machine has a moisture sensor, use it.
• Keep range-top burners and reﬂectors • Clean the lint ﬁlter in the dryer
clean; they will reﬂect the heat better, after every load to improve air
and you will save energy. circulation.
• Use a covered kettle or pan to boil • Use the cool-down cycle to allow
water; it’s faster and it uses less energy. the clothes to ﬁnish drying with the
• Match the size of the pan to the heating residual heat in the dryer.
element. • Periodically inspect your dryer vent
• Use small electric pans or toaster ovens to ensure it is not blocked. This will
for small meals rather than your large save energy and may prevent a ﬁre.
stove or oven. A toaster oven uses a Manufacturers recommend using
third to half as much energy as a full- rigid venting material, not plastic
sized oven. vents that may collapse and cause
• Use pressure cookers and microwave
ovens whenever it is convenient • Consider air-drying clothes on
to do so. They will save energy by clothes lines or drying racks. Air-
signiﬁcantly reducing cooking time. drying is recommended by clothing
manufacturers for some fabrics.
About 90% of the energy used for $ Long-Term Savings Tips
washing clothes in a conventional • Look for the ENERGY STAR and
top-load washer is for heating the water. EnergyGuide labels. ENERGY
There are two ways to reduce the amount STAR clothes washers clean clothes
of energy used for washing clothes—use using 50% less energy than standard
less water and use cooler water. Unless
washers. Most full-sized ENERGY
you’re dealing with oily stains, the warm
How Much Electricity Do Appliances Use?
This chart shows how much energy a typical appliance uses per year and its corresponding cost
based on national averages. For example, a refrigerator uses almost ﬁve times the electricity the
average television uses. Visit www.energysavers.gov for instructions on calculating the electrical
use of your appliances.
STAR washers use 15 gallons of
water per load, compared to the
32.5 gallons used by a new standard
machine. ENERGY STAR models
also spin the clothes better, resulting
in less drying time.
• When shopping for a new clothes
dryer, look for one with a moisture
sensor that automatically shuts off
the machine when your clothes are
dry. Not only will this save energy,
it will save the wear and tear on
your clothes caused by over-drying. Save Energy and More with ENERGY STAR
ENERGY STAR clothes washers use 50% less
• ENERGY STAR does not label energy to wash clothes than standard washing
clothes dryers because most of machines.
them use similar amounts of energy,
which means there is little difference
in energy use between models.