Passive solar system
The site’s orientation, its 30-degree slope and the omnipresence of deciduous trees on the land created a situation close to ideal for the architect/homeowner when he designed his passive solar system. Obviously, the south façade with its large window openings was to be the main source of heat; the west façade also contributes heat gains, particularly during the spring and fall.
The trio of 100-mm (4-in.) concrete slabs provide a 11.7-m3 (411-cf) thermal mass, which stores solar energy. The thermal mass corresponds to the volume of poured-in concrete—and soapstone used for kitchen counters—acting to capture the heat from the sun and gradually release it. The surrounding trees actually play a major role in this scenario, conveniently losing their leaves in the winter when the sun’s rays are most needed, and growing their foliage again in the spring, providing much-desired shade during the summer.
The dimensions of the openings were fine-tuned by consultant Caroline Hachem, a professor at the University of Calgary’s Faculty of Environmental Design. Triple-glazed windows with a low shading co-efficient film were installed throughout the project, maximizing the sun’s input and minimizing heat losses at night. Backup heating is provided by a hot-water radiant system—the water heated through an instant heater located in the mechanical room. The roof’s shape was determined keeping in mind the eventual use of photovoltaic (PV) or thermal panels, hence the 38-degree angle considered optimal in this particular location.
Additionally, intelligent thermostats were installed in the house, keeping track of daily temperature variations and the exact number of hours each of the three levels was kept comfortable without the backup system being turned on. This information can be obtained directly from the thermostats or by going online. It also allows control at a distance and close monitoring of the house at all times.
The house as experimental ground
FPInnovations is a Québec-based forest research centre, with work that has had ramifications for wood building materials around the globe. When the group became aware of Laroche’s project, it showed interest in using the new house as experimental grounds for measuring the way humidity migrates through the walls.
Eight probes were installed in various spots, on the east, south, and north façades—some closer to the CLT panels, others closer to the exterior envelope. These probes have since been providing constant readings, which are translated into graphs. Conclusions will not be drawn, however, until two or three years from now, when the house will have gone through full yearly cycles.
The architect chose to leave the panels exposed inside, electing not to install a vapor barrier. Esthetic reasons led to this decision, but so did the desire to benefit from wood’s ability to absorb and release moisture, creating a comfortable level of humidity in the house at all times.
On the exterior, an air barrier membrane wrapped the face of the CLT panels; a rain barrier membrane inserted over the insulation and under the exterior cedar siding provided water protection. Given this particular wall composition, the fact the house is being tested becomes particularly interesting in view of future interventions.
