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Home energy Q&A

Q: I'm really fascinated by the concept of daylighting that you wrote about a while ago. Last winter was so bleak up here that I really noticed what the day was like without bright light streaming into our house. Can you tell me more about this?

A: As simple as the basic idea is — to use the sun to bring light into a building, the idea of daylighting carries with it much more than just the light.

In presentations I give to teachers and administrators, I show a terrific slide of two side-by-side nearly identical classrooms. One of them has the overhead electric lights turned on and the window blinds closed, while the other has the lights off and the blinds wide open. The warm feeling of the room with the natural lighting makes it the obvious choice when I ask the group which classroom they would prefer to be in.

There's even been some serious research on the effects of daylighting on people. A couple of studies found that students in schools that had extensive use of daylighting had higher scores on standardized test than did students in schools that did not take advantage of daylighting. The students not only did better on the tests, but they were generally healthier, had less dental decay, and had more positive moods. I've also read about a large chain retailer whose stores with skylights had 40 percent more sales than their stores without them. And studies of people working in offices and factories with large windows said they enjoyed their work more than did people whose workspace lacked windows.

While these studies are more anecdotal than hard research, the number of examples makes them worth thinking about. Your experience this past winter is another good example of something psychologists have known for a long time — that people often suffer periods of depression and other problems after living through a long, dark winter.

The best part of this story is that this concept of daylighting is such an easy strategy to put into place in just about any building. Take a look around your house today. Open all the drapes and blinds and walk around your home. Now close everything up and walk around again. The change in feeling can be very strong.

What you want to do to maximize the natural light and warmth the sun can bring into your home is to actively control it. For example, in warm weather, you'll want to close window covers on the east side of the home in the morning and the west side in late afternoon to keep that hot sun from overheating your home. Opening window coverings on other sides of the house will let more diffuse light in. In winter, you can open things up to take advantage of the warmth.

In addition to making you feel better psychologically, the sun can provide warmth in cold weather and light throughout the day, without ever sending you a bill for its work. Controlling the sun can help keep the home cooler in summer and cut down on your use of air conditioning, too. As a result, your home can be more comfortable, you can feel more relaxed, and you can cut down on your energy use.

The same thoughts apply to skylights as well. They provide the same basic benefits, and work most efficiently when you have controls that allow you to shut them off when needed but leave them wide open at other times.

I've had people smile when I've talked to them about daylighting, and I know they're probably wondering why we had to give a fancy technical word to the simple process of doing all that we can to let sunlight into our homes. Once they think about the many benefits that come with it and how the real key to making it work is to control the light that comes in, they appreciate it more as a strategy for improving comfort and reducing energy use.

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(Ken Sheinkopf is a communications specialist with the American Solar Energy Society (www.ases.org). Send your energy questions to askken(AT)ases.org.)

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(c) 2009, McClatchy-Tribune Information Services.