Glass wall heats 'n' cools

Forty-nine discarded windows mounted on the wall of Kevin Stewart's home here gave him a 480-square-foot passive solar heater that not only paid for itself the first winter, but has furnished air conditioning the last two summers as well.

Mr. Stewart first covered the south wall of his 70-year-old house with aluminum printing-press plates, which had been given to him by a local printer. The plates were then painted black. Next, he fastened the windows, also salvaged from a hotel being torn down, to vertical 2x4s.

A one-quarter-inch plywood casing at the top and sides backed by insulation contains the warm air.

When the heated air reaches 100 degrees, a fan in the basement of the house is triggered. The fan pulls air down from the top of the collector through a 7 -inch stovepipe and pushes it into the house.

The fan then turns itself off when the air temperature drops to 80 degrees.

Mr. Stewart's total out-of-pocket cost for the solar wall was about $300; however, $180 of it was recouped through federal and state tax credits. The balance, or $120, was easily paid back through savings on oil during the first winter of 1979-80.

When summer arrived Stewart found that by opening several collector windows at the top of the unit, plus opening the house windows in both the north and south walls, the collector's swiftly rising hot air pulled cool air into the house as it vented the heated air.

Result: natural air conditioning which was free.

Discarded wood windows from old buildings all across the country are no good for saving energy in their original form, but they can become amazing energy savers when turned into passive solar heaters.

The house here in Mansfield, Mass., proves it can be done.