Green Tips for a Cool Summer

A green guide for keeping your home cool this summer, from simple steps to bigger projects.

Medically Reviewed by Michael W. Smith, MD on July 14, 2009
8 min read

Keeping our houses cool with air conditioners costs Americans about $11 billion a year. And those air conditioners release about 100 million tons of carbon dioxide into the air annually -- two tons for each home that has one.

With the demand for home air-conditioning systems in the U.S. at an all-time high, summer’s toll on the environment is probably going to get worse.

The good news is that by following some green tips at home this summer, you can cool off, save money, and make a sizable dent in your carbon footprint. “If we can reduce carbon emissions from homes just 5%, it’s like taking three-quarters of the cars off the road,” says Trey Muffett, building science director for Sustainable Spaces, a home performance retrofitter in San Francisco.

Your eco-cooling steps can be as big as installing insulation in your house or as little as changing some of your everyday habits. “I always encourage people to go for the low-tech solutions first because you can do those starting tomorrow,” says Aaron Pope, manager of sustainability programs for the California Academy of Sciences.

The lowest-tech ways to keep cool this summer start with your own body.

  1. Wear clothes in natural fabrics. “Fabrics such as cotton, hemp, and linen ‘breathe’ better than synthetic fibers and naturally wick moisture away from the body,” says Kimberly Rider, author of The Healthy Home Workbook.
  2. Eat cool. Dine on salads and sandwiches instead of large, protein-rich meals when the weather is hot, as these can warm your body up. Oven- or stove-top cooking heats up your house as well.
  3. Stay hydrated. Avoid alcohol and caffeine in the heat, as these can promote dehydration. Drink more water than usual or consider an electrolyte replacement drink if you’re sweating a lot.
  4. Cool off with water. Soak your feet in a tub of cold water, put on a wet bandana, or take a cool shower. Keep a spray bottle of water in the refrigerator and spritz yourself regularly throughout the day.
  5. Head down and out. When your home is at its hottest, remember that the basement is the coolest place in the house. Or plan outings to air-conditioned buildings -- such as the library or a movie theater – during peak hot hours.

Try some of these low-tech practices around the house.

  1. Use windows and window coverings to your advantage. If you’re not home during the day, close all windows, curtains, and blinds to keep your house cool for as long as possible. If you’re home during the day and don’t want all the windows covered, cover them when needed. Remember that south-facing windows get a lot of sun. East-facing windows get sun in the morning and west-facing ones get the hotter and stronger sun in the afternoon and evening. Dark-colored curtains, roman shades, and even dime-store roller shades can be very effective. “Roller shades can block up to 80% of solar heat,” Muffett says. If the air cools down enough in the evening, open the windows to promote as much air circulation as possible.
  2. Don’t add to the heat inside. Use appliances such as irons, washers, and dryers at night or early morning -- or eliminate the dryer altogether and use a clothesline instead. (Not running your appliances between 4 p.m. and 6 p.m. also helps avoid brownouts.“A big source of heat is your stove,” Pope says. “So if you can, cook outdoors or microwave meals.” Microwaves use two-thirds less energy than stoves. Another option is using a toaster oven for baking. Because toaster ovens are so much smaller, they don’t warm up a kitchen like a conventional oven. And, depending on the model, you’ll be cutting your energy use in half. Turn off computers and other appliances when not in use. Left running, these can also generate unnecessary heat. You can also unplug these appliances when not in use to ensure you reduce your electric bill as well, because the small amount of power these pull while plugged in can add up on your bill over time.
  3. Consider changing your bulbs. Incandescent light bulbs are heat generators, so many experts suggest switching them for energy-efficient compact fluorescent light bulbs or halogen infrareds. Fluorescent “corkscrew” bulbs contain mercury, so consider the safety risks before putting them in children’s bedrooms, playrooms, or other places where they may be likely to break.
  4. Use fans. When it cools down outside, place inexpensive portable fans in front of open windows to bring the cool air inside. And consider installing a ceiling fan if you don’t already have one. Attic fans also circulate cool air from outside through the house. Use ceiling or room fans even if you have an air conditioner. You can then set your thermostat higher because the air movement from the fan will help the room feel cooler.
  5. Keep your refrigerator well stocked. Refrigerators that are full of food don’t warm up as quickly when the door is opened, so they require less energy to stay cool.

Shading from the inside with curtains and blinds is a good first step, but shading from the outside can be even better.

One of the least expensive ways to do this is by installing awnings. The Department of Energy estimates that awnings can reduce solar heat gain – the amount the temperature rises – in your house by as much as 77%. Patio covers can also shade from the outside.

Other more costly exterior shade options include woven mesh solar screens that hang outside, solar control windows, and reflective film on windows. Window film, which is actually a microscopic layer of metal that repels solar radiation, can block anywhere from 50% to 70% of solar heat.

Depending on where you live, two other cost-effective solutions can be a big help.

  • Dehumidifiers. In regions such as the Southeast, humidity makes hot air feel hotter than it actually is. “If you take the humidity out of the air, the temperature feels much cooler,” Pope says. “Dehumidifiers are not too expensive and they’re much more energy-efficient than a whole air conditioning system.”
  • Swamp coolers. In desert climates, people used to sleep in screened-in porches, sometimes hanging wet blankets or sheets inside the screen and using a fan to help draw the air through the moist fabric. Evaporative coolers, also known as swamp coolers, operate on the same principle. They draw in fresh air from the outside, pulling it in through moist pads and circulating it with a big fan.

Swamp coolers can be costly -- from $200 to $700, plus installation. But they can lower the temperature of outside air as much 30 degrees and use up to 75% less energy than air conditioners.

Despite their name, swamp coolers are only effective in dry climates.

Try some of these strategies for cutting costs and energy consumption with your air conditioning system.

  1. Keep the filter clean. Dirty filters limit airflow and make the unit run longer. Clean or replace the filter every month or so during the summer.
  2. Make sure your air conditioner is in good working order. Air conditioners require professional maintenance to keep them working effectively. “Every couple of years, you want to have someone come in and do a tune-up,” Pope says.
  3. Set your thermostat higher. Try it at 78 degrees when you’re home and 85 degrees when you’re out.
  4. Install a programmable thermostat. “If you set it to kick in an hour or half-hour before you get home, you won’t even notice, and you’ll be saving a lot of energy,” Pope says.
  5. Shade your air conditioner. Don’t locate central air conditioners in direct sunlight. Place window units on the north side of your house, which remains more shaded. A shaded air conditioner uses up to 10% less energy to operate.

If you’d like to take some bigger steps, consider this: The federal stimulus package signed into effect last year offers incentives to encourage energy efficiency. For example, homeowners who invest in new insulation, duct seals, or energy-efficient windows or cooling systems can receive a tax credit of up to $1,500 if the work is done in 2009. With the energy savings you’ll gain, you might recoup some of the costs over just a few years.

Before you invest in any equipment or improvements, get an assessment of your energy needs. Utility companies often provide them for free, and they’re also available from private companies. “The best thing is to gather information about your home so that you can make decisions based on real information and data instead of guessing,” Pope says.

For example, sealing ducts and building leaks, and improving insulation, can cut your energy usage up to 70% (for both heating and cooling), depending on where you live.

Here are some bigger projects you might consider.

  • Bulk up your insulation. If your home was built more than 20 or 30 years ago, you probably have very poor insulation, Pope says. Most experts consider this one of the best energy investments.
  • Install a whole-house fan. Whole-house fans installed in the attic draw cool air into your home through the windows and force hot air out through attic vents. They cost between $150 and $400. Installation costs depend on access to your attic. “Whole-house fans cost one to five cents an hour to run, compared to 20 cents an hour for air conditioning in a warm state such as Georgia,” Muffett says.
  • Seal your ducts. Leaky ducts account for 25% of cooling costs in an average home. If your leaky ducts are in the attic, for example, you can lose a lot of cool air there.
  • Invest in a new air conditioning unit. If yours is on the way out or more than 10 years old, replacing it with an Energy Star rated unit can save 20% to 40% on cooling costs.

Before it gets too hot this summer, plant a few trees. Trees don’t just provide shade. Through a process called evapotranspiration, they also cool and moisten the air.

Pope advises buying trees that won’t need a lot of water or care, and planting them strategically. In temperate climates, for example, planting deciduous trees such as maple and ash west and southwest of your house will block sunlight in summer but let it in during the winter. Trees also add to the beauty of your home, boost property values, and provide a perch for a rope swing -- a great place to cool off on a summer evening.