Abstract: A below grade heat recovery system discharges air into the drainage system below the floor slab and around the perimeter of a house or building. This air may be warm and moisture laden air ventilated from the building so that a portion of its energy content will be transferred to the surrounding soil, thus raising the soil temperature and reducing below grade heat losses. Pressurization of the sub-soil layer will reduce radon and soil gas transport from the soil, through the floor slab into the basement. Reduced foundation movement will also be reduced by the supply of a relatively constant flow moisture into the soil with the discharged air.