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That Cool Blast of AC Is Not So Cool for the Planet. What Can You Do?

Sunday, June 15, 2008

In terms of global warming, the truth about air conditioning is chilling. According to the Department of Energy, one-sixth of American energy use goes toward cooling buildings, a particularly large proportion given that most air conditioners operate for only about one-quarter of the year. Another way of looking at it: Keeping your home cool this summer will add one to three tons of carbon dioxide to the atmosphere.

In this era of climate change concern, air conditioning is a troublesome paradox: It works by forcing hot air outside, making the outdoors even hotter. In densely packed cities, that heat gets trapped, making cities less able to cool when the sun sets. The more fossil fuel energy we consume in our quest to stay comfortable, the hotter the atmosphere gets, and the more air conditioning we use as a result.

It's worth keeping in mind that humans have gone without air conditioning for millennia; it was not until 1928 that the first home systems were introduced and not until the 1950s that they caught on. For generations, people in multi-story houses would sleep on the ground floor or in basements during the dog days of summer. Spicy foods -- which increase circulation, taking heat away from the core of the body and inducing sweating -- have helped ease high temperatures through the ages.

Of course, air conditioning isn't going anywhere. The Washington area's summers are notoriously hot, and too much heat is a health hazard. New technologies are making climate control greener: Geothermal systems draw heat from the ground in the winter and deposit it there during the summer. (President Bush's Texas ranch has one.) And some home-cooling systems powered partially by solar panels have hit the market. SolCool ( http://www.solcool.net) offers hybrid systems that can even produce drinking water in more humid environments; prices start at about $5,000, plus installation costs.

That said, there are plenty of simpler ways to minimize your carbon footprint while beating the heat. Here are a few:

· Strengthen your first line of defense against the sun's rays. Close blinds in the morning to keep the sun out. Add solar film to your windows, or if you're buying new ones, choose double-glazed and solar-protective models. Consider installing window awnings, and plant trees or install window boxes to create more shade. Last, seal any cracks. "The average American house has gaps around its windows and doors that, combined, equal a 3-foot-by-3-foot hole in the wall," says Jenny Powers, a spokeswoman for the Natural Resources Defense Council. Good insulation can also save 20 to 35 percent on cooling costs, she says.

· Ventilate. Run fans, which are far less power-intensive than air-conditioning units, and create a cross breeze by opening windows.

· Unless you have pets, don't leave the air conditioning on all day if you're out. Buy a programmable thermostat if you have central air conditioning; it will pay for itself in energy savings. Keep the temperature as high as you're comfortable with. Air conditioners are significantly more efficient when running above 72 degrees, and even more so at 78 degrees or higher.

· Keep your air conditioner's coils clean, and change filters regularly. Install units on the north side of your home if possible; the sun is less intense there, and a unit operating in the shade uses 10 percent less electricity, according to the Energy Department.

· Seek out appliances with the Energy Star seal. If your AC unit is more than a few years old, the energy savings of a more efficient model are likely to outweigh the energy used to produce the appliance. (To recycle the old one, call your county household hazardous waste service.)

· Contact your power company about switching to renewable-energy credits. This will allocate your monthly energy payment to investment in wind or other clean-energy sources. It may not absolve you of all guilt, but it certainly can't hurt.

-- Eviana Hartman

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