What lessons can we draw from the Solar Versus Superinsulation debate of the early 1980s?
- Just because many solar houses of the 1970s and 1980s had design and construction flaws, doesn’t mean we should reject passive solar design principles or active solar heating systems.
- South-facing glazing — especially sloped glazing — is a double-edged sword. While it admits plenty of heat — sometimes too much heat — on sunny days, it can lose a lot of heat on cold nights.
- While active solar systems are expensive and require regular maintenance, thick insulation is long-lived and trouble-free.
- The Achilles’ heel of many active solar systems is their parasitic energy use — that is, the electricity required to run pumps and blowers. Some solar air systems used so much electricity for fans that cynics concluded that most of the homes’ space heat came from waste heat emitted by the blower motors.
- Spending thousands of dollars on solar hardware for a house that hasn’t been carefully air-sealed and superinsulated is putting the cart before the horse. Nine times out of ten, if a designer takes the time to design a tight, well insulated envelope, the heating load is so low that active solar equipment no longer makes sense.
- If you really want an active solar heating system, go ahead and install one — but only if you’ve got a very tight, very well insulated house with triple-glazed windows.
- For the most part builders are insulting walls very tightly these days, the best being done with foam and with thermal breaks. The advent and general use of Low e glass coatings takes care of unwanted heat gain in summer and reflects heat back inside. Some well placed south facing windows will do much to gain heat in winter.