Passive solar on the cheap
January 8th, 2009Nate Hagens at The Oil Drum has a good introductory post about simple solar design. Hagens provides this slick diagram that shows the basic concept at work.
This basic design isn’t nearly as efficient as the Passivhaus – but it’s simple, and can be done cheaply.
This is the concept Irina and I followed when we first renovated our house, which was nothing more than a pole-barn sheepshed converted (badly) into a dwelling, back in 1994. Fortunately the building was oriented to face the south (which is one of the reasons we purchased the property). We closed up most of the east- and west-facing windows and enlarged and added windows on the south side, with double-glazed glass. We laid black tile over the concrete slab floor to absorb heat (too bad we couldn’t insulate under concrete, which could easily be done with new construction). Wall insulation was R-19, ceiling R-30. All this was done for a few thousand dollars – cheap (we later replaced the roof with a white steel roof, which added considerably to the cost, and summer performance).
And the house has performed well. Without any heating or cooling other than a small wood stove, it’s warm and cozy in winter, and cool in summer except for a couple of hours in the late afternoon/early evening on the few very hottest days which a small fan makes tolerable. A couple of cords of wood gets us through the winter.
Starting from scratch would have made it possible to increase performance by better sealing, insulating the floor, and controlling thermal mass more precisely. But then consider all the energy saved by recycling an existing structure. We’re happy with the results.