Passive Geothermal Heating and Cooling in the Straw Bale House

Strawbale Farms Passive Geo-Thermal HeatingThe Strawbale House takes advantage of the natural heating and cooling abilities of the earth.

The building is one level on a floating or bell slab. We did not insulate under the slab, since we felt that this would cut us off from this natural heating and cooling. Instead we used 2 inch rigid foam insulation on the vertical sides of the foundation slab, than we used 4 foot by 8 foot sheets of rigid foam, butting them up tightly length wise to the bottom of the foundation at a downward pitch for drainage.

This created a 4 foot insulation barrier around the foundation called perimeter insulation. This helps capture the natural 55 degree F ground temperature in winter and creates what is called a heat sink in summer to naturally draw heat out of the building. We also believe the perimeter insulation helps prevent winter frost heave.