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According to a reliable estimate, over 40 million homes in the United States are inadequately protected against winter and summer weather. These homes are poorly caulked or weather-stripped, lack tight-fitting storm doors and windows or, most important, have poor insulation in their ceilings, walls and floors. If they were effectively protected, the savings would come to nearly a fifth of the money spent for home heating and cooling every year.
Because poor insulation accounts for the greatest waste of fuel, this section tells how to improve the insulation you already have and how to install it in areas that have none. In each case, the object is the same: to block the flow of heat into or out of the house. Heat always flows from an area of higher temperature to one of lower, just as water flows from a high point to a lower one. Some materials are good conductors of the flow of heat—the aluminum or copper bottom of a pan, for instance, quickly passes heat from the flame below to the food above. Others, like the asbestos pad that keeps the hot pan from scorching a countertop, resist the flow.
Wood, sheet glass, metal and solid masonry—the materials used to build a house—are generally poor resisters of heat flow. Certain natural and man-made insulating materials, however, resist it superbly. A modern fiberglass blanket only 6 inches thick blocks the flow of heat as effectively as 8 feet of solid brick wall. Unfortunately, many homes do not take advantage of such powerful insulators. Older houses, built when fuel costs were comparatively low, saved on insulation but waste electricity, oil or gas. To make them economical today, they need a systematic program of analysis and installation.
First compare the insulation you have with the insulation you need. Next check to see that your insulation is at the right level—first at the attic or roof, where warm rising air causes the greatest heat loss, then at exterior walls, and finally in the basement or crawl space under the house. The cost of rectifying insulation deficiencies can usually be recovered in fuel savings within four years—some times in as little as two—and the result is a house that is not only less expensive to maintain but more comfortable in all weathers.
Windows and doors call for a different treatment. They can't be insulated in the usual way, but they do form paths of heat loss in winter and unwanted heat gain in summer. Storm windows or doors—essentially double windows or doors, with a layer of insulating air trapped by a sheet of glass or plastic—can cut these losses and gains by as much as half. and for the special problem of summer glare and heat, there is an old-fashioned solution with some new-fangled improvements—awnings, now often made of plastic or aluminum, or plastic window films that serve the same purpose.
Forms of insulation. Though they all have the same function—to block the flow of heat out of or into a house—these insulation materials come in a bewildering variety of forms. Clockwise from the top are three fiber batts, one without a vapor barrier, the others with barriers of paper and foil; a glob of plastic foam; and heaps of vermiculite, perlite and cellulose loose insulation. Rigid foamed plastic boards are shown in the center.