Chill out without letting the electricity bill
get you hot under the collar.
By Dan Seitz Updated: July 14, 2020
Air conditioning makes it
much easier to work through the summer. In fact, it’s an important tool
for public
health. But running your AC also increases your utility bill, drives
up pollution by forcing power plants to burn
more fossil fuels, and makes
hot nights even hotter.
If you’re ecologically
minded, you can look into installing renewable power for your house or buying
energy from renewable sources. But whether you care about the environment or
just hate the giant bill at the end of the month, one easy fix is to use less
air conditioning.
Outside the house, regulate your body temperature and
drink lots of water. Inside, you can do a lot to drive down the
temperature before you flip on the AC.
Heat and
humidity
When going without air
conditioning, you need to consider two factors: the overall heat and the
humidity. On a hot day, sweating is
a surprisingly effective method of returning your body to its core temperature.
As the droplets on your skin transition from liquid to gas, their evaporation
pulls warmth away from your body, cooling the blood underneath your skin, which
goes back to your body’s core, reducing your overall temperature.
Moisture in the air,
however, stalls this process. In meteorological terms, humidity is the amount
of water vapor the atmosphere can hold. The more humid it is, the less space
there is for your sweat to evaporate. And without your body’s natural chilling
system, everything feels hotter. (Just to rub it in, humidity is likely to be
higher in warmer months, so as the temperature is reaching its highest pitch, your
sweat will be at its least effective.)
What this boils down to is
that keeping cool is a matter of getting as much sweat as possible to evaporate
off your skin. To do that, you need to keep relatively dry air moving across
your body. And your home’s setup can help you do that.
Take
advantage of your architecture
Chilling out your
environment is largely a matter of working with convection—the tendency of hot
air to rise. The best way to cool off a room is to pull heat up and out. As a
bonus, proper ventilation also controls humidity, so that gross sticky feeling can
fly away, too.
First, take a look at the
layout of your house. Hot summers aren’t a new problem for homebuilders, and
older houses may have design features you can use.
For example, “shotgun”
houses, which are one room wide and extend back, create cross breezes through
screen doors and open windows. A cross breeze helps pull away hot air, making a
home feel more comfortable. You can enhance these breezes with electric fans
(more on that later).
Houses with large
wraparound porches also maintain lower temperatures. That’s because the
external structure absorbs the direct sunlight, allowing the inner rooms to
avoid overheating.
In some cases, cooling
features might be blocked off. Cupolas, for example, were originally designed
to give hot air a place to escape a home. But when builders installed central
air in older homes, they might have turned those chimneys into attics. If you
clear any blocked vents or spaces in your attic, you may notice (and enjoy)
better air circulation.
Keep out
sunlight
A lot of warmth comes into
your home via sunlight. In individual rooms, you should control these rays
with blackout
curtains or shades. If you still want sunlight, open the curtains on
windows that don’t face the sun directly; this allows indirect sunlight to
filter in.
The color of the curtains’
outward-facing side also matters. We see color because that particular
wavelength of light bounces off an object. Because heat radiates as infrared
light, “hot” colors like red, orange, and yellow will deflect the most warmth.
Of course, not everyone
enjoys living like a vampire. If you need more direct light, consider solar
screens and window tints instead of curtains. These treatments can remove
certain wavelengths of radiation while letting others in.
Another useful technique,
if you have a green thumb (and
sometimes, even if you don’t), is houseplants. Certain types of
plants—including xerophytes like cacti, aloe, and succulents; “air plants” like
bromeliads; and any greenery that doesn’t require frequent watering—get their
water from the air around them. If you grow them in windows or window boxes,
they’ll sponge up a bit of humidity while blocking some of the sunlight.
However, not all greenery thrives in muggy conditions, so ask at your local
garden center to find the ideal plants.
Place
your fans
Fans don’t cool the air,
per se. Instead, they set air in motion, which helps clear away your body’s
evaporated perspiration. So you should place them to maximize air flow.
To start, place electric fans in your windows (if
they open). Try to set the blowers as high up as possible, ideally in the top
sash. They should face outward to suck out hot air out of the room. If you have
a two-story house, concentrate your fans in the upper story’s windows (or at least
lower those windows’ top sashes), where they can help convection pull hot air
up and away.
Ceiling fans can also help.
If you have them, look up and ensure they’re turning counterclockwise. That
way, they’ll pull hot air toward the ceiling.
In addition to enhancing
convection, fans can set
up a cross breeze. If you’re between these flows of air, you’ll feel more
comfortable. To establish cross breezes, don’t think in just two dimensions. A
fan in the door will move air, and another in the window will do the same—but
if you set them up strategically, the door fan can blow cool air onto you while
the window fan pulls hot air away.
Spend a little time
designing a “fan network” in your house. This should keep air moving through
the rooms so you have constant flow.
Manage
humidity
When things feel miserably
humid, a few dehumidifiers can
make a room much more comfortable. A dehumidifier really is the only machine
for the job—wall-unit ACs can remove humidity, but science works against them.
To draw water out of the
air, you must reduce it to the dew point, the temperature at which water
transitions from gas to liquid. The condensers on the back of your air conditioner
can indeed go below the dew point; if you see water dripping out of an air
conditioner, that’s exactly what’s happening. The issue is that the dew point
isn’t a fixed number.
As a rule of thumb, the
higher the humidity, the closer the dew point is to the outdoor temperature. At
80 degrees Fahrenheit and 75 percent humidity, for example, the dew point is 71
degrees. But at 52 percent humidity, it’s 59 degrees. Even if your window unit
can cool the room to that point, you will be shiveringly uncomfortable.
So unless it’s extremely
hot, extremely humid, or you’re really unlucky and it’s both, don’t rely on the
wall unit to pull mugginess from the air. For the truly miserable days, get a
dehumidifier.
Shut down
appliances
On a blazing day, you’ll
want to limit the sources of heat in your home. In the kitchen, avoid you hot
oven and try cooking food in separate appliances, such as pressure cookers or microwaves, that
don’t generate such high temps. Or just stick to uncooked meals like salads.
Beyond cooking, other
appliances can also produce unnecessary heat. For example, you should wash
dishes by hand instead of running the dishwasher. In the bathroom, leave
blow-drying and other hot grooming practices off your personal regimen—at least
for the summer.
Time your
AC use
These techniques won’t cool
down the house quite as much as a central air system or a few well-placed wall
units, but they will make your house more comfortable. And you can still use
these systems in concert with air conditioning: They can lower the temperature
of your home so that when you do crank on the AC, you require less of it—and
you waste less power.
When you finally turn on
the air conditioning, remember to use it efficiently. You don’t want to waste
that cold rush, so check your windows for leaks, which you can seal up with
weather stripping. If your home has a garage or breezeway, try to enter and
leave your house through those locations instead of letting chill air escape
when you open a door directly outside.
Just like hot air rises,
cold air sinks—and you need to control this tendency. For example, in any room
where you have AC, cover the heating vents to prevent cold air from sinking to
the basement. You should also avoid wasting energy on rooms where the climate
doesn’t matter. So close the doors of the empty spare bedroom and the storage
closet while the air is running.
With the units themselves,
you should install devices that have energy-saver modes. Some of these will
automatically shut off when the air reaches a goal temperature; others have
timers you can configure so the units will leave the house at a warmer level or
shut off entirely when no one’s home.
If you have a central air
system, help it
along with a smart thermostat such as a Nest.
These devices will learn your AC habits over time, and can modulate the air
flow to save energy.
Whether you want to save
the planet, save the power grid, or just save a few bucks, you can avoid
overheating—with minimal AC.
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