I am sitting in the future as I write this story, one of many possible American futures in the 21st century like some sci-fi story about parallel universes. It’s a place that is difficult for me to believe and, like any good sci-fi story, when I tell others about it they express disbelief. I live in a different kind of new house. It looks just like a new traditional style 4000 sq. ft. house and cost about the same to build, but it uses 70% less energy to heat than a comparable size new home. It is a passive solar house that costs about $900 -$1100 per year to heat when crude is in the $90-$100 a barrel range.
As a new occupier since June 2008, this first heating season I am experiencing strange new things. For instance, on January 3, 2008 the day started out at -10° F here at 8 a.m. in Fly Creek, NY (just 2 miles north of Cooperstown, NY of Baseball Hall of Fame renown). My auxiliary heat cycles off when the thermostat reads 68.7° F, which it did read at 8 a.m. It was sunny all day. By 1p.m. the house had warmed up to 75.7° F inside while it had warmed to 7.7° F outside. By 6 p.m. the house had cooled down to 68.7° F while it had dropped to minus -0.4° F outside. So on a sunny single digit day my house did not have to use any auxiliary heat for 10 hours. It was simply heated by the sun. Strange.
On a warmer February 5, 2008 evening, when the overnight temperature was in the mid 30s, I started my woodstove at 6 p.m. and it warmed up the house past 72° F. The fire went out about 10 p.m. The next morning the thermostat read 69° F. The auxiliary heat did not need to go on at all when it was just above freezing all night. Very strange.
Strange, but true. And like many unexplained phenomenon, it has a simple explanation once it is carefully examined. A passive solar home operates on three related concepts: A source to get the energy (heat) in the house, a way to store it, and a means to keep it from seeping out.
The following explanation is a truncated over simplification of the how the house functions. To clearly understand how the Kosmer Solar House Project was built and how it works go to my website.
The primary source for heat is the sun. It comes in through south facing windows, which is why passive solar homes have many windows on their south wall. Auxiliary heat is needed when the sun does not supply enough energy. We have a high-tech propane Baxi boiler with Baxi solar hot water panels to preheat the water for both domestic hot water and closed loop hot water for heat.
Heat storage is supplied by a one-foot thick concrete slab solar thermal storage battery under the house. The house works on the on the simple physics of a cup of coffee. Everything wants to even out to the same temperature. Pour hot coffee in a cold mug and within minutes the mug heats up and the coffee cools down until they are the same temperature. That principle is how the solar thermal concrete storage battery works. The slab stores excess heat and then releases it slowly as needed to stay in equilibrium with the house.
We keep the heat in by creating a thermal envelope using 2 layers of 2″ thick foil backed Dow Tuff-R rigid insulation on the exterior of the walls, under the slab and on the roof. It’s like building a soda picnic cooler, except you’re the soda. This insulation performs over three times better than fiberglass insulation.
This is not some experimental technology. Bruce Brownell, the solar engineer that tailored the passive solar system in the house I designed, has been creating these passive solar home systems for over 30 years. He has worked on homes from 1000 – 5000 sq. ft.
Imagine a future where you spend 70% less to heat your new home. Imagine a future America where everyone spends 70% less to heat their home. This is the possible American future I want to be in.
John Kosmer has been the Home Improvement Editor of Victorian Homes Magazine for the past 23 years.