The EnergyChoose the right appliances to curb
your home’s energy appetite
BY aleX Wilson
W
hen it comes to electricity consumption, the kitchen is the
hungriest room in the house. Kitchen appliances—including refrigerators, freezers, ranges, and dishwashers—account for nearly 27% of household electricity use.
Collectively, that’s more than 300 billion kilowatt hours (kwh) per year in
the United States, or roughly the electricity output of 90 average-size coalfired power plants.
not all appliances are equally voracious,
however. refrigerators and freezers account for nearly twothirds of kitchen energy
where does the
energy go?
kitchen appliances on average
account for more than a quarter
of household electricity use, and
the appliances we use to keep
food cold—refrigerators and
standalone freezers—together
are the biggest consumers. ovens, coffeemakers, and cooktops, as a group, are the secondhungriest appliances in the
kitchen, followed by dishwashers.
10%
26%
use, with ranges, ovens, and cooktops accounting for
a little over one-quarter, and dishwashers the rest.
add in the heating, air conditioning, hot water, and
lighting used in a kitchen, and this room is clearly the
energy hog of most houses. Putting your kitchen on
an energy diet might be one of the best things you can
do to save money and resources. like most diets, it all
comes down to making informed choices.
refrigerators are the top energy guzzlers
in a typical american home, the refrigerator accounts
for about 15% of total electricity use. assuming heat
and hot water are not electric, that makes the refriger54
64%
Two tools to measure energy efficiency
The blue Energy Star label and the yellow EnergyGuide sticker help consumers identify energy-efficient appliances. Energy Star labeling indicates
compliance with guidelines set by the U.S. Environmental Protection Agency
and the U.S. Department of Energy. Appliances rated by the program include
dishwashers, refrigerators, and freezers (but not cooking appliances). While
Energy Star compliance identifies an energy-efficient appliance, some models
exceed the requirements more than others (see www.energystar.gov). Unlike
the voluntary Energy Star program, the EnergyGuide label is required by the
Federal Trade Commission on all fridges, freezers, and dishwashers (but not
on cooking appliances). The label shows the model’s capacity, its estimated
annual energy consumption and operating costs, and a scale that compares
its efficiency to that of similar models. The EnergyGuide label helps in comparison shopping but does not indicate Energy Star compliance.
fine HOMeBUilDinG
COPYRIGHT 2007 by The Taunton Press, Inc. Copying and distribution of this article is not permitted.
Drawing: Matt Collins
Smart Kitchen
refrigerators: Style and use determine efficiency
What to avoid
Frugal features.
The most-popular features with
consumers—such
as automatic
defrosting and
through-the-door
ice and water dispensers—are not
always the most
energy efficient.
Still, Maytag’s new
Ice20 refrigerator
meets Energy Star
requirements and
is equipped with
two potentially
energy-saving
features: an alarm
that alerts homeowners to a refrigerator door left
ajar, and a vacation
mode that saves
energy by limiting
automatic defrosting when the fridge
isn’t opened for
several days.
• Through-the-door ice and water dispensers. Both the lost insulation and the
additional cooling coils in a through-the-door ice and water dispenser increase
electricity consumption.
• Automatic ice makers. Ice makers consume energy, though exactly how much
is difficult to determine.
What to look for
• The Energy Star label. The U.S. Environmental Protection Agency confers its
Energy Star label on models that are at least 15% more energy efficient than
the federal minimum. Reading the label is an easy way to be sure that the
refrigerator you choose is not an energy waster.
• Freezers on top or bottom. Side-by-side refrigerators use more energy.
• Manual defrost cycles. The most energy-efficient refrigerators and freezers
have manual defrost, although they can be hard to find, particularly among
high-end models.
• Door alarms. Some manufacturers offer an alarm that will sound if the
fridge door is left open—helping to save energy and to prevent food spoilage.
Maintaining High performance
• Place fridges away from heat sources—especially a range or oven, but also a
dishwasher. Radiant heat from these appliances warms the surface of the
fridge, requiring more energy to keep the inside cool. If the refrigerator must
be adjacent to a heat source, provide space for air circulation.
• Clean the coils, at least annually. Dust and dirt buildup on
refrigerator/freezer coils reduces the heat-exchange efficiency
to watch for
and makes the compressor work harder. Most refrigerators
Vacuum-panel insulation. Thermos bottles keep coffee hot because
now have coils that can be accessed from the front, eliminatmost of the air molecules in the double wall have been removed, keeping
ing the need to pull the unit away from the wall.
conductive heat transfer very low. The same idea has been incorporated
• Turn off the condensation-control feature. Essentially, these
into flat vacuum panels. Back in the mid-1990s, Whirlpool produced
are heating elements under the protective shell that conhigh-efficiency refrigerators that used inch-thick vacuum panels made by
sume energy in two ways: by using electricity to warm the
Owens-Corning, which had center-of-panel insulating values of R-75. The
outer shell and by increasing the difference in temperature
technology was dropped, but with a planned tightening of efficiency stanacross the unit’s insulation. Models with this feature usually
dards, vacuum-panel insulation could be back. Silica-aerogel insulation is
have a switch to turn it off; do so, unless condensation
another material that could find its way into refrigerators; it insulates betbecomes a problem.
ter than the polyurethane foam used in most models (much better if in
• Keep the freezer full. Frozen food serves as a thermal
a vacuum panel).
stabilizer that reduces the amount of on-off cycling. If you
Linear, variable-capacity compressors. Probably the biggest
don’t have a lot of frozen food, freeze containers of water
breakthrough put forth by appliance manufacturers and efficiency pro(use plastic, and allow for expansion as the water freezes) to
ponents today, linear compressors can be as much as 23% more efficient
take up the extra space. When you need ice for a cooler, you
than standard reciprocating compressors, according to Korean appliance
can use these frozen containers.
manufacturer LG. The company currently offers the only refrigerator with
• Don’t keep an extra fridge in the garage. When you buy a
linear-compressor technology. Sold in Europe, it has not yet been intronew refrigerator, avoid the temptation to keep the old one to
duced in the North American market.
store a few six-packs of beer or soda. Recycle it instead.
innovations
www.finehomebuilding.com
Photos: Courtesy of Maytag Corp.
fall/winter 2007
COPYRIGHT 2007 by The Taunton Press, Inc. Copying and distribution of this article is not permitted.
55
Cooking options pit
efficiency against cost
More-efficient cooking saves
energy and money directly,
of course, but by keeping waste
heat out of the kitchen, it also
saves on air conditioning.
Although this impact might
not be huge in a typical home,
it can make a difference. As a
rule, electric cooking appliances
are more efficient than gasfueled ones. But the relative price
of natural gas versus electricity
often makes natural-gas-fueled
appliances a more economical
choice. Gas cooktops also afford
more controllability than their
electric counterparts.
Because their functions are so
different, it’s important to consider cooktops and ovens separately, even though they might
be combined in a stand-alone
kitchen range.
Cooktops & Ovens: Electric wins over gas
Cooktop efficiency is difficult to measure, and relatively little attention has been paid to
it, primarily because stovetop cooking accounts for a small percentage of household
energy use—about 5%, according to the American Council for an Energy Efficient Economy. My research shows that electric cooktops are the most efficient, and gas the worst.
The chart below ranks the most-common cooktop technologies in order of efficiency
based on the energy factor, which is the ratio of the amount of energy conveyed to an
item being heated to the device’s overall energy consumption. Expressed as a decimal,
it reflects the proportion of energy used that actually contributes to the cooking of food.
Cooktop tYPE
56
FINE HOMEBUILDING
0.84
take off when introduced a decade or so ago, it’s back, with
more high-end induction cooktops entering the market. On an
induction cooktop, electrical energy is transferred directly to
ferrous-metal cookware through magnetic induction. Efficiency is
the highest of any cooktop (about 84%) because the cookware is
heated directly. It’s also a safer way to cook: The cooking surface
does not heat up, enabling photos like the one at right, where
water boils in a cutaway pan while ice cubes rest intact on the
“burner’s” surface. Induction cooktops also heat up and cool down
quickly, providing precise controllability. Downsides include high
cost and the fact that only certain cookware can be used. Castiron, enameled cast iron, and some stainless-steel cookware work.
Test yours to make sure a magnet sticks to it, or look for a label.
0.742
Radiant ceramic. The most common mid- to high-end electric cooktop today, it has relatively fast-heating radiant elements
under ceramic glass, providing a sleek, easy-to-clean stovetop
surface. Flat-bottom cookware is needed for good surface contact; older-style cast-iron pans are not recommended because
burrs on the metal can scratch the glass surface. Radiant-ceramic
cooktops heat faster than electric coils and are nearly equal in
energy efficiency.
Gas ovens draw
electricity, too
0.737
Electric coil. Available today on only low-cost ranges and
cooktops, these old-fashioned open-coil elements are slow to
heat up and difficult to clean, but fairly efficient at transferring
electric energy to the pot.
Gas (natural or propane). Cooks prefer gas burners for
gas
With ovens, rapid heat-up and
cooldown aren’t as important as
with cooktops, making electric
ovens more competitive with gas,
even for serious cooks. In fact, it
is not uncommon for high-end
ranges to have a gas cooktop and
an electric oven. Again, electric
is more efficient: Electric ovens
are 1.8 to 3.5 times as efficient as
gas ovens, according to U.S. Department of Energy (DOE) data.
Cost efficiency, however, largely
depends on which type of fuel
costs the least in your area.
Most gas ovens also use a lot of
electricity while operating. In
nearly all gas ovens today, when
the gas burner is operating, an
electric glow-bar igniter (some-
energy factor
Induction. Although induction technology initially failed to
Electric
ator a home’s single largest electricity consumer. This is the case
even though refrigerators have
improved dramatically since the
mid-1970s; today’s models use
about a third as much power as
those from 30 years ago.
speed and controllability, but indoor-air-quality experts often
recommend against gas for health reasons. Gas cooktops
rate worst in terms of energy efficiency, but they are usually more cost efficient because the price of natural gas is
typically a lot lower than electricity. Gas cooktops use only
about 40% of the energy produced, and if there’s a continuously burning pilot light, the overall efficiency is far lower
(about 16%). In some areas, propane is nearly as expensive
as electricity per unit of delivered energy, making electric
cooktops a more economical option. The efficiency of natural gas and propane is essentially the same.
0.156
Without pilot: 0.399
With pilot:
From top: GE Profile induction cooktop www.geappliances.com • GE Profile radiant cooktop
• GE built-in electric cooktop • Whirlpool Gold gas cooktop www.whirlpool.com
Photos: Courtesy of General Electric (top 3). Courtesy of Whirlpool Corp. (bottom).
COPYRIGHT 2007 by The Taunton Press, Inc. Copying and distribution of this article is not permitted.
MicroWave
cooking saves energy
Like their cooktop counterparts, electric-oven elements cook food more efficiently than gas. But the
real energy champions are microwaves, which are five
times as energy efficient as a standard electric oven.
You can see how they rank below.
times called a “gas oven
igniter”) is on, drawing
about 375w. (interestingly,
at the international Builders’
Show in Orlando this year, not
one kitchen-appliance salesperson who was asked seemed to be
aware of this fact.) found in all
self-cleaning models, the glow
bar ignites the gas when the
oven is turned on and reignites it
as it cycles off and on during the
cooking or self-cleaning process.
those 375w (or even as much as
500w in some ovens) are a significant amount of electricity.
if low electricity use is a priority in your home, consider a
model without a glow bar,
such as ranges made by the
Peerless-Premier appliance
TIPS TO CUT
CONSUMPTION
pe
oven efficiency by ty
Energy factor
oven type
Microwave
g)
electric (self-cleanin
)
rd
da
electric (stan
gas (self-cleaning)
gas (standard)
0.557
0.138
0.122
0.054
0.030
Additional insulation.
self-cleaning ovens typically have more insulation
than standard ovens, so
if you have a choice, go
for a self-cleaning model.
the extra insulation keeps
the outer surface of the
range from becoming
too hot during the selfcleaning cycle, but it also
helps the oven to operate
more efficiently.
A fan. convection ovens
have a fan in the back that
circulates air to maintain
more even temperatures.
as a result, either the
cooking time or the temperature can be reduced.
the energy savings from
reduced gas or electricity
use for cooking easily
outweighs the fan’s electricity use.
Top: ge Profile advantium oven www.geappliances.com
Bottom: Premier gas range www.premierrange.com
www.finehomebuilding.com
Lid on or off? if you use a
convection oven, keep the
lid off a casserole dish. otherwise, it will cook no more
quickly than in a standard
oven. on a cooktop, closing
the lid on a pot will retain
heat and reduce energy use.
Consider a Crock-Pot.
slow-cooking, plug-in crockery pots offer an energyefficient way to cook soups,
stews, and other dishes.
Co. (www.premierrange.com),
which operate with a pilot or a
spark ignition.
Microwave ovens are
tops in efficiency
first introduced as a practical
kitchen appliance in 1965, microwave ovens have revolutionized
cooking and offer substantial
energy savings over standard
ovens. they work by producing non-ionizing microwave
radiation (a certain frequency of
radio waves) with a magnetron
top photo: Courtesy of General electric. Bottom photo: Courtesy of Peerless-Premier appliance Co.
and directing that radiation at
the food. the microwave radiation is absorbed by water, fats,
and sugars, producing heat. Because the microwaves penetrate
the food, heating is more rapid
and requires less energy than in
a conventional oven. Microwave
ovens are about five times as energy efficient as standard electric
ovens and more than 10 times as
energy efficient as gas ovens.
increasingly, manufacturers
are combining cooking functions with microwave ovens to
produce a new generation of
“rapid-cook” appliances. these
models combine microwaves
with electric grilling elements so
that food can be browned as well
as cooked. Quartz elements are
often used to create radiant heat,
though General electric’s advantium microwave oven uses a
halogen-lamp element. Convection is another feature offered by
the advantium and some others,
such as turboChef’s Speedcook
Oven. in the future, most ovens
will likely include multiple heating options to speed up cooking
and will serve a wider range of
functions, from defrosting to reheating to grilling.
Exhaust fans are
important to health
exhaust fans add to energy consumption, but their importance
with regard to kitchen air quality—and the health of your
home’s occupants—cannot be
ignored. Chemical impurities in
natural gas, along with incomplete combustion, can result in
dangerous levels of carbon monoxide (CO), causing headaches
and fatigue at low levels and, at
high concentrations, death. Because of this concern, gas ranges
should be installed with quality,
outdoor-venting range-hood
fans, which should be operated
when the cooktop or oven is on.
exhaust fans are most efficient
when placed above the cooktop
fall/winter 2007
COPYRIGHT 2007 by The Taunton Press, Inc. Copying and distribution of this article is not permitted.
57
dishwasherS: Less hot water equals less energy use
What to look for
• The Energy Star label. Energy Star-qualified
dishwashers are at least 41% more energy
efficient than the federal minimum. Keep in
mind that some models exceed the standard
significantly more than others; check the
EnergyGuide label or the list of qualifying
dishwashers at www.energystar.gov for
high-performing machines.
• Soil sensing. With this technology, “fuzzy
logic” is used to determine how dirty the
dishes are. Water use and wash cycle are
adjusted accordingly, saving significant
water and energy.
• No-heat drying. Most dishwashers have an
electric heating element and fan for drying
dishes. Make sure the one you buy has a
no-heat drying option, which can save a
significant amount of energy.
Usage Tips
• Insulate hot-water pipes from the water
heater so that water stays hot all the way to
the dishwasher and doesn’t cool off as much
between the different wash and rinse cycles.
• Wash full loads only, even if it means waiting a
day or two.
• Avoid high-temperature cycles. Many dishwashers have a setting for more intensive cleaning in
which the temperature is boosted, which can
significantly increase electricity use per cycle.
To conserve energy, don’t use this setting.
innovations to watch for
Steam-cycle dishwashers. LG has introduced a steam-cycle
dishwasher that the company claims cleans dishes better. The washing cycle uses steam at over 200°F, apparently saving energy in
the process (because it uses a lot less water). The dishwasher was
unveiled at the 2007 Kitchen/Bath Industry Show and should be
available this fall.
Drawer dishwashers. The New Zealand company Fisher &
Drawerful of savings.
Compact dishwasher
drawers can be highly
efficient (both of these
models from New
Zealand manufacturer
Fisher & Paykel are
Energy Star compliant).
An added bonus is that
the integrated models,
like the one pictured
above, blend seamlessly
into kitchen cabinetry.
Paykel and KitchenAid both offer drawer-type dishwashers. They
can save energy and water by allowing you to use one smaller
drawer rather than a partially loaded full-size dishwasher, or by
allowing two drawers to be operated at different cycles.
Condensation drying. While most dishwashers vent moist
air into the kitchen as dishes are drying, Bosch models use
condensation-drying technology, which the company claims
improves hygiene and saves energy.
58
FINE HOMEBUILDING
Top: Fisher & Paykel model DD603I www.fisherpaykel.com
Bottom: Fisher & Paykel model DD603SS
Photos: Courtesy of Fisher & Paykel Appliances. Facing page: Courtesy of Bosch Appliances (top two). Courtesy of LG Appliances (bottom).
COPYRIGHT 2007 by The Taunton Press, Inc. Copying and distribution of this article is not permitted.
Top performers. Introduced in July, the Bosch
Evolution line includes
dishwashers that exceed
the minimum federal
energy-efficiency standard by 147%—far more
than any Americanmade dishwasher, using
approximately the same
amount of energy as a
dishwasher half its size.
Easy button.
The “EcoOption”
button offered
on some Bosch
dishwashers allows homeowners to reduce energy usage by up
to 25%. Activating the feature
lowers the wash
temperature
and extends the
cycle by a few
minutes.
or range. Downdraft fans, which
are installed at the back or in the
center of a range, rely on significant airflow (and power consumption) to ventilate cooking
fumes effectively. Because fumes
are more easily channeled into a
fan installed in a range hood, fan
performance is better.
If you can’t vent an exhaust fan
outdoors, avoid the use of gas
cooking appliances. Recirculating range-hood fans can remove
odors but should not be relied on
to remove combustion gases.
A significant energy-saving
feature to look for in a rangehood fan is a variablespeed motor. It allows the
fan to operate at a lower
airflow rate when full
ventilation capacity is not
needed, thus saving energy and reducing noise.
Dishwashers are
shaping up
A new way to clean
dishes. Recently introduced, the LG steam
dishwasher uses only 2.8
to 3.2 gal. of water in an
average load.
Top: Bosch Evolution dishwasher, model SHE98
www.boschappliances.com • close-up Bosch Evolution SHE68 (800
series) Bottom: LG steam dishwasher, model LDF9810 www.lgusa.com
www.finehomebuilding.com
Dishwashers have
changed quite a bit in
recent years. They use
a lot less water, which
translates into lower energy use for water heating. In 1978, water use by
dishwashers ranged from
11 gal. to 15 gal. for a normal dishwashing cycle.
By 2000, that usage had dropped
to 6 to 10 gal.
As water use has gone down,
total energy use has also
dropped, while the proportion of
energy use for other than water
heating has risen. In 1978, 83%
of the total energy use for dishwasher operation was for heating water, with 10% for motor
operations and 7% for drying.
By 1994, energy use for water
heating had dropped to 56%,
according to a 2003 Virginia
Tech report.
However, that does not mean
most dishwashers are as energy
efficient as they could be. Nearly
all dishwashers today have
booster heaters that increase the
temperature of incoming water
to about 140°F to improve wash
performance. An integral electric element provides this heat,
and it can use a lot of electricity. Recent independent testing
shows that booster heaters operate throughout the dishwashing
cycle, resulting in total electricity
use per cycle of 2.0 to 3.5 kwh.
Used an average of 215 times
per year (the frequency DOE
assumes), a dishwasher could
easily consume more electricity annually than a refrigerator.
More research is needed to determine the significance of this
electricity use.
Dishwashers vary considerably in their energy use, much
more so than refrigerators. For
comparison, dishwashers are
rated by the federal government
according to their energy factor (EF), a measurement based
on the energy usage for an average number of cycles (a completely different formula than
the one used to rate cooking
appliances). The higher the
EF, the more efficient the dishwasher: The current federal
standard mandates a minimum
EF of 0.46; Energy Star dishwashers must meet a minimum
EF of 0.65. The most-efficient
dishwashers have an EF that
approaches or slightly exceeds
1.0. Although the EF is used
to compute the annual energy
consumption and cost estimates
found on the EnergyGuide label
on many appliances, the EF itself might not appear there. □
Alex Wilson is founder and
executive editor of Environmental Building News and
president of BuildingGreen
Inc. in Brattleboro, Vt. (www
.buildinggreen.com). His latest book, Your Green Home
(New Society Publishers,
2006), was reviewed in Fine
Homebuilding #184.
fall/winter 2007
COPYRIGHT 2007 by The Taunton Press, Inc. Copying and distribution of this article is not permitted.
59