Great care was taken to not use any off gassing materials. There is no formaldehyde in the dry wall or the oriented strand board. All paints and varnishes used contain no volatile organic compounds.
Trees from lot being milled into flooring
The sun wall faces a southern wall of large triple pane windows that let direct sunlight hit the sun wall in winter months. In summer, extensive roof overhangs shade the sun wall keeping it cool due to the sun's higher position in the sky.
The Passive Geothermal Room is a long narrow un-insulated room below ground level, isolated thermally from the rest of the house. It gets no heat or air conditioning and maintains a temperature year round of approximately 50 - 60 degrees much like a cave or root cellar. Fresh air for the entire house is drawn into this room from the exterior and travels 25 feet down the length of the room before it enters the heat recovery/furnace system. The outside air traveling through this unconditioned space changes temperature passively before entering the heat recovery/ furnace system.
tech. notes - If, for example, the outside temperature is zero degrees, the house takes in that zero degree air and pushes it through 25 feet of air whose temperature is in the low 50's. By the time that volume of air reaches the heat recovery/furnace intake it will be in the low 40's instead of its original zero degrees. So you only have to heat the outside air from the low 40's up to 68 - 70 degrees instead of heating from zero to 68-70 degrees saving 2/3 of your energy colsts before the air even gets to your furnace.
The trees that were removed from the yard for construction, including red oak, white oak, cherry and walnut were taken to a local saw mill and turned into planks for the home's flooring. The smaller branches or stumps were are being used by a local elementary school at their playground.
The lannon stone used in the landscaping came from a local motel that was torn down.
A detail of the aluminum panels covering the sun wall.
Passive geothermal room
Tightly insulated homes like this are required to take in fresh air from the outside and expel stale inside air thoughout the day to maintain good air quality. In winter cold outside air is drawn in and heated - only to be expelled after it has circulated in the house for a bit wasting a lot of heat. The heat recovery ventilator recovers the heat from this warmed air and recycles it back into the house before expelling the stale air. This enables the heat from the passive solar wall to keep circulating in the house even on cloudy days.
Phase change material, BioPCM, is a plant based material the consistency of butter. It absorbs heat when it melts (phase change from solid to liquid) and releases heat when it solidifies (phase change from liquid to solid). The phase change material is encased in a plastic sheet 16" wide that works like bubble wrap with the bubbles being approximately 1.5" square and filled with PCM.
In winter the sun heats a two story sun wall (trombe wall) covered in aluminum panels filled with phase change material called BioPCM. This phase change material has thermal properties similar to a 10" - 12" stone wall, absorbing heat during the day and releasing heat at night.
Heat recovery ventilator
The home's envelope consists of 2" x 6" construction insulated with one inch of closed cell spray foam and blown in fiberglass giving the exterior walls an R value of 30 and the ceilings an R value of 47. The windows are triple pane with argon gas and low e coatings except for those along the southern facade so that the solar wall can gather as much heat as possible.