26 super tips for saving money on cooling and
air conditioning costs
In the typical
home, air conditioning uses more electricity than anything
else -- 16% of total electricity used. In warmer
regions AC can be 60-70% of your summer electric bill,
according to Austin Energy. If you're serious about
saving energy, address your cooling costs first, since
that's what uses the most electricity.
Of course, you'll save the most money if you can learn
to do without your AC at all. It's definitely possible.
I live in Texas and have only rarely used AC. A combination
of ceiling fans, insulation, and the other tips below keeps
me comfortable -- and saves me hundreds of dollars every
summer. I could take a trip to Las Vegas every year from
what I save by not using AC.
A window unit AC uses 500 to 1440 watts, while a
2.5-ton central system uses about 3500 watts. That's a
lot of energy. A floor fan uses only 100 watts on the
highest speed, and ceiling fans use only 15 to 95 watts
depending on speed and size.
Let me put into perspective how wasteful central AC
is: Running your AC 12 hours a day for three weeks uses
more energy than than leaving the refrigerator door open 24
hours a day for a whole year. (Fridge
open 24/7: 180 watts x 13 extra hours day x 365 days/yr. =
854 kWh.)
|
The Air Conditioner
itself |
|
1. Use an AC
timer. |
|
For central AC, install a programmable
thermostat with a built-in timer.
For window unit AC's, just buy a plug-in timer
from a home improvement store.
Either way, set the timer or thermostat to turn off
about the time you leave for the day, and to turn back
on a half hour before you get home. Contrary to popular
belief, this does NOT use more electricity than having
the AC constantly maintain a cool temperature; it uses
less.
You can get programmable thermostats and plug-in
timers from your local home improvement store.
Programmable thermostats come with instructions, but
it's a quick job for an electrician if you're not
comfortable doing the installation yourself. Plug-in
timers for window units start out at $5, and there are
more expensive models with more features. |
It's a myth that leaving the AC on while you're
away at work uses less energy than turning it on when
you get home. Here's why:
Heat goes to where it's not. With the AC off, your
house will absorb heat from outside, but at some point
it will be so hot it can't absorb any more heat. When
you come home and turn the AC on, the AC has to remove
the accumulated heat only once.
But if the AC is on when you're gone, then your house
is constantly absorbing heat because your AC is
constantly cooling down the house. The AC has basically
turned your house into a heat magnet. So your AC is
removing absorbed heat over and over and over
again.
Let's say you leave the AC off, and your house
absorbs 20k BTU's of heat and then stops, because that's
all it can absorb.
Now let's say that you have the AC running instead.
The house absorbs 5k BTU's of heat, so the AC kicks in
and removes it. Then it absorbs another 5k BTU's, and
your AC kicks in and removes that. Repeat that process
several times during the day.
This is not a gray area, and there's no question
about it: running the AC when you're not home wastes
energy, period. |
|
2. Raise the
temperature |
3. Try doing without
AC, or just using it less |
|
Try cooling your home to only 80 degrees (or
warmer) instead of the 70's. This is especially easy
to do if you have ceiling fans. Each degree below 78
will increase your energy use by 3-4%. |
Many of us here in Texas actually get by without
using AC -- good use of ceiling fans and box fans is
really enough. Wearing a wrung-out wet shirt also does
wonders, as does a quick rinse in the shower every
couple of hours. (The amount of extra water used is
negligible compared to the amount of electricity saved.)
If you can't do without it AC completely, setting it at
85 degrees or higher and using fans will still save you
a lot of money. |
|
Two products that keep you
cool at night so you can keep the AC off:
Chillow
The Chillow is a water-filled
pillow that keeps your head cool while you sleep. You
can either sleep directly on it or put it inside a
pillow case. I bought one as soon as it came out and it
really works. Order
for $30. |
Bed fan
Most people prefer
to sleep with covers, even though that traps the heat
your body creates. So you can run an expensive AC to
cool the whole house just so you can be comfortable
under the covers...or you can simply use a Bed fan. It's
a small, gentle fan that operates right under the
covers.Why didn't someone think of this before? This
could be great for people who experience night sweats or
hot flashes. And you won't have to run an expensive AC
all night long. /I>. |
|
4. Don't cool unused
rooms |
5. Replace your old
AC |
|
If you don't use your whole house, it's cheaper to
use window-unit or portable AC's to cool only the rooms
you use, rather than central AC to cool the whole
house. Of course, close the doors to unused rooms.
If you have central AC and are opposed to getting
window units or portable units, you can close registers
in rooms you're not using so you're not paying to cool
them, but note that if you close too many of them, the
pressure in the system could cause leaks in the ducts.
Check with an AC professional first to see how many
& which registers are safe to close at the same
time. |
According to Austin Energy, today's AC's [2005]
use 30-50% less electricity than 15-year-old models.
When shopping, look at the SEER rating for central
systems and the EER rating for window units. The higher,
the better (more efficient, cheaper to operate).
As of Jan. 2006, AC's must have a SEER of at least
13, although they go as high as 19. Both the inside and
outside units should be a similar SEER for best
efficiency. (See <more about SEER from
Climate Magic.)
It is important to get the right size AC, and
replacing your old AC with one of the same size is often
a mistake. An AC that's too small OR too big will be
inefficient and waste energy. For window units check out
the AC sizing calculator, and for both
window & central systems see more
about AC sizing from the Dept. of Energy. |
|
6. Clean the
filter |
7. Cool your
condensor |
|
Clean or replace your AC filter every month. A
dirty filter makes your AC work harder, which uses more
electricity. Your home improvement store sells permanent
filters which you can wash with a garden hose so you
don't have to replace the filter each month. |
An AC
Mister makes your AC run more efficiently by
cooling the condensor with water vapor as it runs.
Evaporative cooling is an old concept so I have no doubt
that it works, but I haven't tested this product so I
can't say how well it works. The drier the environment,
the better the performance will be. |
|
8. Use an evaporative
cooler instead of air conditioning |
|
An evaporative cooler is a big
box fan that blows water-cooled air. It can be
either free-standing in your room, or it can sit outside
the house and blow the cooled air in through a window.
Evaporative coolers use a lot less electricity than an
regular air conditioner, and they work well in dry
climates (like Nevada, West Texas, etc.) -- but they
don't work in very humid climates at all. Here's a
map showing cooler effectiveness by region. Be aware
that they use a lot of water -- 66 gallons a day according to the
average in one study. (visit an evaporative cooler store...) |
|
9. Install a
geothermal system |
|
Geothermal systems use 30-60% less energy than
typical HVAC systems, run quieter, and require less
maintenance. They can also heat your water, too, and
in the summer it's free, since the water is heated with
heat that's already been extracted from the house to
keep it cool.
A geo system is a loop of piping under the ground
that circulates water. The heat is extracted from your
home, run through the pipes, and the earth absorbs the
heat from the water. Basically, the heat is taken out of
your home and put into the earth. This isn't so
different from a traditional AC system, which extracts
the heat from your home and puts it into the air
outside your home. A geo system is just a lot more
efficient and cheaper to run.
Geothermal heat pumps meet the EPA's Energy Star
guidelines if they're labeled at least COP 2.8 for
heating and EER 13 or for cooling. |
In 2006 a geo system cost about $2500 per ton of
capacity to intall. A 3-ton geo system at $7500 compares
with $4000 for a traditional system, for a $3500
up-front premium for the geo system. (EPA) A geo
system could save in the neighborhood of $700/yr.,
paying for itself in less than six years, not even
counting the lower maintenance costs. Also, many city
and state governments offer rebates and other incentives
for installing geo systems, making it an even more
attractive deal. On the other hand, depending on the
geology of your area and the availability of local
contractors, a geo system could cost a lot more than
$2500/ton to install.
I had a hard time finding really good figures to base
my calculations on, but the above should be in the
ballpark. For AC, I'm figuring 50% savings over a 3-ton
(4200-watt) AC system running 12 hours a day for five
months. There's also savings on heat, even if the old
heat source was gas or oil, but heating savings are
harder to figure, so I'm estimating that they'll be a
bit below the savings on cooling. (Here's
a cost comparison of different systems from GeoExchange.org,
PDF.)
More from:
|
|
10.
Install ceiling fans if you don't have
them. |
|
Fans can make the temperature seem 10 degrees cooler,
tremendously reducing your need for AC. And ceiling fans
are cheaper than you might expect: they start out around
$25 at your local home improvement store. Most people
are even able to install them themselves using the
instructions provided. |
Ceiling fans use very little energy. A typical 36" /
48" / 52" ceiling fan uses about 55 / 75 / 90 watts of
electricity respectively at the top speed (and the top
speed is most efficient for cooling you).
Don't underestimate the importance of ceiling
fans.
|
|
11. Make sure your fan
blades are spinning the right way. |
|
Make sure your fan is blowing DOWN, to send air past
your body, removing the hot air that surrounds your
body. If your fan is blowing up, it won't do
any good. In fact, it will make you warmer by bouncing
the warm air that collects at the ceiling back down
towards the living area.
It's true that a fan that blows down also
pushes the warmer air down from the ceiling into the
living area, but it's blowing even warmer air away from
your body, so the overall effect is to cool you
down.
Most fans have a switch to change the fan direction.
It's an up/down or left/right switch on the side of the
fan (between the light and the fan blades), and it's
usually unlabeled. Make sure the fan is off (not
spinning) before you flip the switch or you can damage
the motor. |
Once you've turned the fan off, it's fine to
physically stop the blades with your hand, just be
gentle so you don't bend the blades, otherwise the fan
will wobble when you turn it back on. With the blades
stopped, flip the direction (summer/winter) switch, then
turn the fan back on.
So how do you know which direction is up and which is
down? For most fans, when you're standing under the fan
looking up, counter-clockwise blows down and clockwise
blows up. Check by standing under the fan when it's on
full-speed. If you can feel the wind hitting you hard,
then it's blowing down. To verify, stop the fan, change
the direction switch, then turn the fan on full-blast
again and compare the
difference. |
|
Attic, Roof, and
Exterior |
|
12. Insulate the
attic |
13. Install an attic
fan |
|
Poorly insulated attics can lose up to 40% of a
house's cool air. The average home built in 1985-90 has
R-11 to R-15 insulation but needs R-49. See the DOE's
map for how
much insulation you need depending on what part of
the U.S. you live. (Baltimore Gas & Electric says
that increasing the level of insulation from 2-3 inches
(R5) to 8 -14 inches (R30) can save $95 to $145 per year
for every 1,200 square feet of ceiling area.) Also, an
attic radiant barrier (aluminum foil sheeting) stapled
across roof rafters can reduce energy use 3-8%. |
Install a simple attic fan to push the hot air out
of your attic. Just attach it to the gable vent
that's already in your attic and you won't even have to
cut any holes. It'll cost about $1/mo. to run 24/7, or
you attach it to a solar panel and run it for free.
Austin Energy says reducing the attic temperature by 10
degrees or more saves up to 10% on AC costs.
|
|
14. Install a radiant
barrier |
15. Test your ducts
for leaks |
|
A layer of aluminum foil-type material or special
paint across the underside of the roof in your attic
blocks up to 95% of heat radiated into the roof.
Besides decreasing the amount of attic heat that
radiates into the living space, it might reduce the heat
enough that you could consider turning the attic space
itself into a living space.
|
Austin Energy tested thousands of home duct systems
and found that the average home loses 27% of its heating
or cooling from leaky ducts. (June 2006) According to
the Los Angeles Times (1-25-01), studies show
that 25% of homes lose up to 1/3 of their heating or
cooling from leaky ducts. See if your local utility will
perform a free or rebated duct test, and have any leaks
repaired.
Those in hot climates like the Southwest U.S. should
use mastic sealant because regular duct tape will dry
out. |
|
16. Paint the exterior
with a light color |
17. Install a metal
roof |
|
The next time you have your home painted, use a light
color. According to Insulad,
dark colors increase cooling costs by 20% compared to
light colors.
|
Metal roofs reflect much more heat away from your
home than do regular asphalt shingle roofs. If you don't
like the way metal panels look, there are newer metal
shingles that look like attractive wood shingles.
Another benefit is that metal roofs are permanent
so you never have to replace your roof again (unlike
asphalt shingles, which must be replaced every 15 years
or so). |
|
18. Plant shade
trees |
|
|
Well-positioned shade trees can reduce indoor
temperatures by up to 20 degrees and energy use by up to
40%.
|
|
|
19. Make sure your
doors and windows are well sealed. |
20. Use drapes or
blinds to block sunlight |
|
You'll pay a lot more to cool your home when the cold
air easily escapes. Do-it-yourself weather stripping for
doors and caulk for windows is easy to install, and
cheap. Also make sure to caulk around the holes where
pipes go into the wall under sinks.
Also, close the damper to the fireplace when you're
not using it -- otherwise, cool air will escape through
the damper. |
Keep direct sunlight out. Direct sunlight can raise
the temperature of a room by 10-20 degrees. The less
heat gets into your home, the less you have to pay to
remove it. Drapes block sunlight and heat better than
blinds. |
|
21. Put solar screens
on the windows |
22. Install reflective
film on windows. |
|
Solar screening is a special mesh that reflects much
more sunlight than regular screening. It's available at
home improvement stores, and can block 60-70% of the
heat from sunlight. Get screens that don't block too
much light, because if your building gets too dark and
you wind up using more lighting inside as a result
(which generates heat) then you've defeated the purpose
of the screens. |
According to the California Energy Commission, 30% of
a structure's cooling requirements are due to solar
energy entering through glass. (source)
Reflective film reflects the sun's heat from your
windows, and can block 40-60% of heat and modern films
reflect heat away without blocking the light too,
so you can still have nice, bright rooms. Film costs
about $3-7.50 per square foot installed, or
do-it-your-selfers can get the material from a home
improvement store for about $1-2 a square foot. The
payback period is 3 to 5 years (or maybe less, if the
cost of electricity continues to rise). It's critical to
use film that blocks very little light, otherwise you'll
run more lighting inside which will heat up the building
and defeat the point. (more from ChiefEngineer.org) |
|
23. Use storm windows
& doors |
|
|
If you're ambitious, install storm windows and doors.
They can reduce the amount of cooling or heating lost
through single pane glass by 50%.
|
|
|
24. Reduce heat from
lighting |
25. Reduce heat from
cooking |
|
Lights create a lot of heat which your AC system has
to remove. Replace your lights with compact
fluorescent (CFL) bulbs, which use 75% less energy
and create 70-90% less heat at the same time. Regular
lights give off 10% light and 90% heat, while CFL's give
off 90% light and 10% heat.
Whatever kind of lighting you have, turn it off when
you're not using it. It's not just using electricity,
it's adding heat. (But don't try to heat your home with
lights in the winter, either; lighting is an
inefficient way to generate heat.) |
Any heat you create from cooking has to be removed by
your AC. Reduce cooking heat by using a microwave oven.
(Microwaves
are cheaper to operate than gas or electric ovens
anyway.) |
|
26. Use software to
model your building |
|
|
For those who want good data, you can get software to calculate the heat gain and
heat loss in your home or business. |
|
|
Other
tips for Central AC's |
- Shade the outside
condensor unit.
Condensors in the shade use up to 10% less
electricity than those in direct sunlight.
- Don't block the
condensor unit. Tall
grass and other debris on or around the condensor can
restrict air flow and use more electricity.
- Clean the
condensor/evaporator coils at the beginning of each
season. You can wash
the fin coils on the outside with a garden hose.
Unless you know what you're doing, have the coils on
the inside serviced by an AC specialist.
|
|
Other
tips for window units |
- Make sure you're
using an energy-efficient model. If you have an old, inefficient unit,
buying a new one will pay for itself quickly in lower
electricity bills. I recently noticed two AC's in the
same house, designed to cool the same sized area, but
one used 1440 watts while the other used only
600.
The EER (Energy Efficiency Rating)
tells you how efficient an AC is. The numbers range
from 8 to 11.5, and the higher the better. The EER of
window air conditioners rose 47% from 1972 to 1991.
(David Darling)
If you replace an old EER 5 unit with a new EER 10
unit, you'll cut your cooling costs in
half.
(Trivia: The EER is
the number of BTU's divided by the number of watts.
BTU's are British Thermal Units, and refer to how much
heat an AC can remove from a room in an hour. A 7000
BTU window unit that uses 655 watts has an EER of 7000
/ 655 = 10.7. Central AC systems are so large they're
measured in tons instead of BTU's. One ton = 12,000
BTU's.)
- Make sure your AC
is the right size for your room. A unit that's too small OR too big is
inefficient and wastes energy. Check out the AC sizing calculator at Consumer
Reports to get the right size AC.
|
The Fan Switch. Here's how the fan switch works: If
the AC is off, then turning the fan on will simply recirculate
the inside air without cooling it. (It draws in through the
intake and blows out through the ceiling vents as it normally
does.) There's not much advantage to this, because it doesn't
make the house any cooler, but it can help keep the air
"fresh" since it's being drawn through the filter and it's
being moved around a lot.
When the AC is on, the air's already being circulated, so
in that case there's no difference whether the fan switch is
on or off.
The fan by itself doesn't use much energy. It's the cooling
part of the AC system that uses most of the power.
Fans don't make the
air cooler! They work by blowing away the envelope
of warm air that surrounds your body.
As a living creature, you generate heat. A lot of it. As
that heat slowly radiates away from your body, it creates a
pocket of hot air that surrounds you. It's like you're being
insulated by an invisible bubble of heat. What fans do is to
push that hot surrounding air out of the way.
This is why blowing on hot food cools it off. It's not that
your breath is especially cool, it's that you're blowing the
heat off the food.
If you're sweating at all then the fan also cools you by
speeding up the evaporation.
So now that you know that fans don't make the air cooler,
you can see that there's no advantage to leaving the fan on
when you leave the room. Fans don't lower the temperature in
the room at all.
By the way, a typical 36" / 48" / 52" ceiling fan uses
about 55 / 75 / 90 watts of electricity respectively (less on
slower speeds).
CheapElectricityProvider.com helps you to connect, switch,
or transfer your service to a cheaper electric provider.
|
