NRDC's This Green Life
A Journal of Sorts
AUGUST 2005 / Links updated 2013

Our apartment has no central air conditioning -- just three window units. These serve us perfectly well, though we could probably use one more. During the couple of weeks each summer when the mercury soars into the '90s, we closet ourselves behind closed doors in the air conditioned rooms. The rest of the time, we use fans -- or more often, nothing at all.

My mother wonders how I survive. She's accustomed to a climate-controlled environment and Thermometer isn't comfortable in a wide range of temperatures. I have the opposite problem. It's depressing for me to be in a sealed environment where the windows never open. I prefer the feeling and smell of fresh air -- even fresh city air.

There's more than personal taste at issue. Minimizing air conditioner use is important for environmental reasons. Air conditioning is an energy hog, accounting for 16 percent of energy use in the country. As such, it's a major contributor to global warming, as well as smog.

Admittedly, reducing air conditioner use is easier in the Northeast, where I live, than in many other parts of the country, but it's possible everywhere using the following three-pronged approach:

1) Keep heat from entering. To keep heat out, you need to reflect or block it -- especially from the windows and roof where most heat enters. An easy way to block it from windows is with light-colored curtains and shades. Close or pull them down before the sun gets strong on that side of the house. If you plan to be out all day, close them on all sides before leaving.

Outside shutters, louvers and awnings serve the same purpose and are even more effective because they prevent the sun from heating up the windows. Just be sure to choose ones that are easy to adjust, so you can get your sun, air and view when you want them.

About a third of the heat entering most homes comes through the roof. Installing a radiant barrier on the underside of the roof can cut heat gain by 25 percent. Alternatively, apply a reflective coating to the top side. Insulating your attic will not only help with summer heat, but winter chill as well.

Landscaping to block heat can cut your cooling costs by 15 to 50 percent, according to the Department of Energy, while beautifying your property at the same time. Tall trees with spreading crowns on the south side of your home will shade the roof from the midday sun, while shorter trees to the west will block the lower rays of afternoon. Shading paved areas with trees, shrubs or trellises with vines will lower the temperature of the air around your home, protecting it further from the sun's heat, and have the added advantage of making the outdoors more pleasant, too.

2) Remove heat that's inside. Use natural ventilation during the cooler parts of the day and night to bring temperatures down. Open low windows a little bit on the windward side of the house and open high windows a lot on the opposite side to draw the cool air up and through the building. As the air travels, it will pick up heat and send it outside. Make sure inside doors are left open so there's a path for the breeze to take. Ventilate your attic, too, with louvers and roof vents. Maintain the coolness during the hot period of the day by closing your windows. Interior heat increases slowly in a well-insulated house.

3) Avoid producing heat. A number of indoor activities increase the indoor temperature. Cooking is an obvious one. Try using the microwave instead of the stove -- or have cold dinners when the weather is hot. Washing and drying clothes is another. Do these activities in the morning or evening when it's not so hot, and seal off the room so the heat doesn't spread. And while you're at it, seal off your water heater -- or wrap it in a water heater blanket, which helps preserve energy in winter too.

Lastly, replace your incandescent bulbs with compact fluorescents, which emit 90 percent less heat and use 75 percent less energy, year-round, while producing the same amount of light. Don't use electric light at all when natural light is sufficient.

Even if you do all this, there will still be summer days when your home is too hot. That's when mechanical help is needed. I always try fans first. A variety of types are available. Ceiling fans are great for circulating air -- both for cooling in the summer and warming in the winter. When used in combination with air conditioners, they allow you to turn the thermostat up 4° F, which saves considerable energy. Window fans are good for ventilation, though I don't like the fact that they block the breeze when they're not on. Oscillating fans are the cheapest and easiest solution. Just plunk one on the table and point it at you for a great wind-chill effect.

When your comfort requires something more, by all means use the air conditioner. The point is not to suffer, but to alter conditions in and around your home to make it necessary less of the time.

—Sheryl Eisenberg

Printer Friendly Version (requires Adobe Acrobat)
Family photos
Sheryl Eisenberg, a long-time advisor to NRDC, posts a new This Green Life every month. Sheryl makes her home in Tribeca (NYC), where—along with her children, Sophie and Gabby, and husband, Peter—she tries to put her environmental principles into practice. No fooling. Read more about Sheryl.


Join me on Facebook


Cooling Your Home Naturally

Radiant Barrier Fact Sheet

Landscaping for Energy Conservation

Cool Your House with a Window or Attic Fan

Energy-Efficient Air Conditioning

Energy Star

Air Conditioners

Shutters on Italian farmhouse
Cooling, Italian style. None of the vacation homes we've rented in Italy over the years has ever had an air conditioner. Instead, they were outfitted with traditional wooden shutters, like this farmhouse in Emilia Romagna. We found that as long as we closed the shutters in the morning before going out, the houses were generally comfortable when we returned for siesta in the afternoon.

Landscaping options. Evergreens can provide year-round shade and also act as a wind block in winter. Deciduous trees will drop their leaves when it's cold to let winter sunlight through. What you plant, and where, will depend on your climate and the siting of your home. Try drafting a simple plan of your grounds and bringing it to your local nursery for expert advice.

Increasing air conditioning efficiency. For air conditioners to perform their best, they need to be properly maintained. The most important step is regularly cleaning or replacing filters. If you're in the market for a new air conditioner, get an Energy Star model, which guarantees efficiency. Also, be sure to select one that is appropriately sized for your space. Buying an overly large machine -- a common mistake -- will waste energy and money alike.

Sheryl Eisenberg is a web developer and writer. With her firm, Mixit Productions (, she brought NRDC online in 1996, designed NRDC's first websites, and continues to develop special web features for NRDC. She created and, for several years, wrote the Union of Concerned Scientists' green living column, Greentips, and has designed and contributed content to many nonprofit sites.

Share | |
Find NRDC on