Rod Driver

From the South County Independent, Dec. 7, 2005

Take advantage of solar heat


While planning our dream home, my wife and I didnít agree on every detail . But one thing we both definitely wanted was solar heating. So in 1978 we engaged solar expert Spencer Dickinson to build our 1600-square-foot house.

Full solar heating requires three elements: good insulation, heat collection and heat storage. Our walls contain 6-inch thick fiberglass insulation and the ceiling has 12 inches of fiberglass. We have 2 inches of load-bearing polystyrene insulation under the concrete basement floor. Our windows are "double glazed" and almost all of them face south. On a sunny winter day this is enough to keep the house comfortable.

But for nights and overcast days we need to have collected and stored heat. For the "active" solar system, Dickinson put 600 square feet of water-type solar collectors on the south-facing roof and two humungous concrete tanks to hold 8,000 gallons of solar-heated water in the basement. When the sun is shining a small pump automatically sends water from the tanks to the collectors and back to the tanks. Those tanks then serve as hot water bottles to keep the house warm when the sun isn't shining. For backup we have an efficient airtight wood stove which we light occasionally in December and January.

The bottom line is, we haven't had an oil delivery or an oil bill for 26 years.

But practically nobody builds solar homes today. Oil is too cheap. In fact homes are being built without even a nod to passive solar. Windows are sprinkled around all sides, as though the builder had no idea where the sun was going to be each day.

It is seldom practical to retrofit an existing home to full solar heating. However, most people can take steps to let the sun help lower their heating bills in an existing home -- assuming the home has some south-facing windows. The idea is simple: let solar energy in when the sun is shining, then seal up the windows at night and on cloudy days to help retain the heat. Reducing heat losses means improving insulation. Increasing the insulation in walls and ceiling might be expensive. However, unless you have obvious leaks in the walls, windows are probably the worst offenders and at the same time relatively easy to correct.

Hardware and home supply stores sell kits consisting of transparent plastic sheets and rolls of double-sided tape for attaching these plastic sheets indoors over existing windows. The kits cost a few dollars, require a few minutes to install and can be removed in the Spring for reuse the following winter. The effect will be noticed immediately. I know of no bigger bang for the buck.

Somewhat more expensive are insulating window shades or drapes to reduce nighttime heat loss. While insulating shades are desirable, any drapes or curtains are better than none. They should be closed every night and on cloudy days. We have insulating shades or shutters on most of our windows. On the others we use both plastic sheeting and drapes.

In addition to trying to capture and retain solar energy, the other common idea to save heating costs is to burn wood. But a conventional fireplace is worse than nothing! Unless you want to burn extra conventional fuel to make up for the heat loss due to your fireplace (lit or unlit), seal it up for the winter. Or consider installing a free-standing wood stove -- perhaps using the existing chimney. Burning wood does put pollutants into the air. But the occasional use of a wood stove is nowhere near as polluting as full-time heating by oil, electricity or gas.

Closing note: Renewable energy is easily captured at low cost. It might be solar heat, as we have, or electricity from photovoltaic panels, windmills or waterfalls. What is not easy is storage of the free energy. Our concrete heat-storage tanks occupy half the basement, and when reasonably warm they contain no more accessible energy than a gallon of gasoline -- a very inefficient energy-storage system. But until someone makes a major breakthrough, these 26-year-old tanks are about as good as any storage system available.