Passive Solar Design in 1985

Architect Joseph Kawecki and the Pipics demonstrate an emerging concept in passive solar design in 1985.


| March/April 1985



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The Genesis Solar Subdivision is a planned community of passive solar homes.


PHOTO: MOTHER EARTH NEWS EDITORS

Ten years ago, a builder could simply cover the south wall of a house with glass and call it a solar home. The public was hungry for relief from the energy crunch, and passive solar housing was as much a symbol of a solution as it was a fix in itself. Indeed, passive houses did (and still do) demand much less space-heating energy than the norm, but such dwellings have also had a few teething problems over the years. Thankfully, today's passive solar designs are able, in many instances, to overcome those difficulties — largely because of the experience gained by the pioneers of the seventies.

To name just a few of the discoveries made in the last decade in passive solar design, thermal mass has now become an accepted feature in most designs (not just in homes built from adobe, as used to be the case); superinsulation has gradually been mixed with solar features; and designers have recognized that varying the amount of insulation isn't the only response needed in order to adapt to different climates. As a result of these and other lessons, many of the new breed of solar homes don't look as ostentatiously glass-covered as their ancestors, but they perform well and are far more comfortable to live in.

Tom and Crystal Pipic's house, in the Genesis Solar Subdivision near Columbus, Ohio, is a fine example of this refinement in thought on passive solar design. It demonstrates the principles that architect Joseph Kawecki has arrived at after years of doing solar design to suit the exceedingly complex climate of the Midwest. 

Passive Solar Design for a Variable Climate

To give you an idea of the adversity that solar buildings in Ohio must face, consider the following: The January heating degree days in Columbus have a 66 percent chance of falling between 1,000 and 1,400; January typically offers between 2 and 6 clear days, but they're most likely to come in one string; and actual clear day radiation values typically vary 10 to 15 percent from the predicted averages. Thus the heating load on a house in the Columbus area is very likely to vary by at least 40 percent over several decades, and the direct solar gain that will be available to meet that demand can be counted on to be small and fickle. These sorts of conditions are enough to leave a designer mumbling, "How much glass? How much mass?"

The obvious response to an unpredictable climate is to stress insulation in preference to solar features. But does that mean solar technologies should be abandoned in the Midwest? Not at all. Kawecki's design still achieves approximately a 40 percent solar contribution to space heating. Let's look at how.

First, the Pipics' house can definitely be called superinsulated. The walls are built from 2-by-6s (16 inches on center with 5/8-inch drywall for solid walls) and are filled with fiberglass and sheathed with 1-inch foil-faced polyurethane on the outside — for an R-value of about 30. The ceiling has 15 to 16 inches of blown-in cellulose, giving it an R-value of roughly 50. The perimeter of the crawl space is insulated on the inside of the block footings with 1-inch foam, a vapor barrier and foil-faced 6-inch fiberglass that laps a foot onto the floor. To reduce infiltration, electrical receptacles in the exterior walls were kept to a minimum, and no recessed lighting was used in the second floor ceiling.





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