In winter, snow drifts collect on the roof and around these walls to provide extra insulation where it is needed. The entire south side of the 1500 square foot house is devoted to collecting solar energy. Vertical south windows and a greenhouse, both double-glazed, occupy the lower part. The 590 square feet of trickle-type collectors originally installed in the upper wall are covered with two panes of glass because of the extremely cold weather. Solar heated water drains to a 1000 gallon tank surrounded by 35 tons of crushed rock.
Air blown through the rock carries heat to the house.
Water is pumped upwards through the cavity between these plates and drains form the roof ridge to the basement tank. The rock-air storage system was also replaced by a passive storage system. Although not as crucial as winter heating in the Minnesota climate, summer cooling is part of the south wall forming an overhang that keeps almost all summer sun off the south windows. Natural ventilation through vents in the north wall and roof ridge, aided by evapo-transpiration from the sod roof, carries off excess heat. Local funding has also generated local involvement.