This passive solar house is situated on 0.6 hectares (1.5 acres) facing slightly east of due South. The insulated concrete formwork (ICF) construction allows for maximum air and wind tightness and achieves an R-value of R-29 (RSI 5.3) in the walls. The attic is insulated to R-50 (RSI 10.6). There is an insulated 1.22 m (4′) frost wall and the floor of the house on slab construction (no basement) is insulated to R-10 (RSI 3.6). All windows are EnergyStar rated double-glazed.
The high-efficiency windows, air-tight construction, and high insulation values allows the house to take maximum advantage of the passive solar feature, storing the solar heat in the concrete floor and keeping the heat longer. The house has the added features of dual flush toilets and EnergyStar-rated high-efficiency appliances.
The 6 arrays of evacuated tubes are mounted on the roof of the garage. Solar exposure of the arrays is intentionally limited to help reduce any over heating. The evacuated tube is the primary heating system for the in-floor radiant hot water heating system and for all domestic hot water use. The system has two 250 L storage tanks that are used for the in-floor heating system, and a heat exchanger that transfers the heat within the domestic hot water tank. The solar evacuated tube loop is filled with of polypropylene glycol (food grade) and water. The solar evacuated tube system reaches liquid temperatures of 90 °C (194 °F). The system has a built in heat dump to expel excess heat in summer and though there is no outdoor pool produces enough heat in summer to heat an average backyard pool. The system is equipped with an electric back-up boiler for periods when there is a lack of solar energy — too many cloudy days.
The family, including the dogs, is very satisfied with the even heating throughout the house as there are no cold spots. They estimate they are saving $60 per month in summer for cooling and domestic hot water and about $250 per month in winter. The owners have had some minor problems and would make adjustments to the system. Snow build up on the arrays is a problem, though minor and felt the arrays should be in a single row to help alleviate this problem. Another minor problem was they felt the thermostat controlling the in-floor heating was located in too open an area, the stairwell, causing the heating system to reach higher temperatures than necessary.
