The Passive Solar House

The Complete Guild to Heating and Cooling Your Home

(2006)
James Kachadorian

Finished Reading: 03.2010

The Passive Slab system, developed by Kachadorian in the 1970's, includes a poured concrete slab over standard concrete masonry units. The voids in the CMU's (which are placed side by side, on their sides) are used for air circulation and the movement of heat into the home. With the help of a small fan for air movement, the resident of a passive solar house can enjoy a moderate temperature year round without the use of a active heat source! The light from the sun comes in through the windows, and the heat is trapped because the home is constructed tightly with minimal leakage. Window coverings can help keep the heat from escaping through the glazing at night.

Kachadorian is writing from his experience building homes in the Northeast, in places like Vermont and Connecticut, and based on most of the examples given, assumes we are going to build our solar house in a very cold climate. His houses seem to be built out in the middle of nowhere, but this doesn't affect the design at all, and a solar house can be built in the city or anywhere - in a cold or mild climate. In areas with fewer days of sunshine, it is still beneficial to collect the solar rays that do fall on the site, though it may not be enough to eliminate back-up power.

He includes very detailed instructions on how to calculate the sizes of windows, slabs, and to see how much energy will be gained and lost throughout the day. This method varies some from other Passive House designs, which concentrate rigorously but simply on maintaining a tight envelope with proper air exchange, rather than a fancy slab and operable window coverings. Importantly, whatever type of house is being designed, the architect should consider the location of the sun, and use that ball of gas burning billions of miles away for as much free heat as he can get from it. Keep that electric heater off!