Q-We put a radiant barrier in our attic, and it was money well spent. Attic temperatures have dropped about 30 degrees. But we still have another problem: heat buildup on the brick exterior. The afternoon sun bakes unshaded portions of the exterior of the house, and it is not feasible to plant trees for shade. Would painting our bricks white make a difference?
A-A light wall color is a good alternative to exterior shade. Experts say that air conditioning costs in a typical one-story house with unshaded white walls will be about 8 percent lower than for a home with dark, unshaded walls. In terms of what it can mean in this house, the solar absorption of a light-colored brick surface is between 35 and 50 percent; the absorption of light red brick is 50 to 60 percent; and the absorption of burnt-red brick is 65 to 70 percent.
Thus a light-colored brick surface will absorb far less solar heat than will a darker color brick, keeping the walls cooler and the interior of the home a lot more comfortable.
Q-I am a graduate biologist with an interest in baking food domestically in solar ovens. Where can I find design plans for solar ovens, or where can I buy them?
A-These products are popular in developing countries and are often the only method of heating food. The Solar Energy Industries Association (122 C St., N.W., Fourth Floor, Washington, D.C. 20001) will send you the names and addresses of solar oven manufacturers. There is no charge.
You also can contact Solar Cookers International, a nonprofit organization that promotes solar cooking. It publishes a newsletter with recipes and a lot of information on making your own solar ovens and on hundreds of projects around the world where solar ovens are in use. The address is SCI, 1724 11th St., Sacramento, Calif. 95814.
I recently received a letter from Bev Blum, executive director of the organization, about a previous article I wrote on solar ovens in which I said that these products are not recommended for cooking meat because they don’t reach the high temperatures needed to kill bacteria. She disagreed with me.
Whatever cooking method is used, she said, if meat or any other raw food is fully cooked, it is safe from disease germs. She sent me some detailed research papers supporting her statements.
I had based my previous warning on what I have heard over the years from some home economists. They had warned that cooking meats in a solar cooker was not recommended for meats such as fresh pork because very high temperatures are needed over long periods of time to kill trichinosis.
I suggest you contact the people at Solar Cookers International for details.
