The Charrette...

While all mechanical options were on the table, I went into the Charrette thinking that I might like to use a Stirling Engine (see: www.whispergen.com). A Stirling Engine is a fossil fuel burning device that produces hot water and electricity. I’d first seen one being tested at the National Research Council a few years earlier and I was keen to see if it could produce all of the hot water I needed for the radiant slab or domestic use while offsetting some of the electricity we would otherwise have to buy from the local utility. Through contacts at Natural Resources Canada who had a Stirling Engine they were keen to test in an energy efficient house, I was offered a device for free and flown out to Calgary with my Electrical and Mechanical contractors to see a test unit in use. All of this background work had been done by Saturday March 1st when 15 or so of us convened for the Charrette.

The list of participants included several luminaries from the energy efficient housing community, one of whom, Bruce Gough, had prepared a detailed heat loss analysis of the design. The plumber and mechanical contractor unfortunately couldn’t make it that day but our electrician and project manager were there along with several DAC staff.

Before getting underway we made a field trip to the Snye, trudging through the snow to get a better sense of the site and how the house responded to its surroundings.

As promised, Ken Klassen facilitated the day and did a fantastic job of pushing us to consider the big issues and pulling us back from dead-end roads. In no time we had dismissed the Stirling Engine in favor of a much simpler approach that better suits a building with a good envelope. Along this line we also eliminated geothermal heat pumps and other expensive kit where the promise of lower energy costs wasn’t enough to offset high capital and maintenance costs.

Much to my dismay there was some criticism of the architecture, difficult questions about the location of the screened porch and the size and layout of the Master Bedroom for example. One of the recurring themes was that at 2,200 sq. ft. the house was just too big and if I was really serious about conserving energy I’d make it smaller. I often found myself on the defensive in an effort to avoid going too far backwards on the basic design. In the end I realized that some of these points were spot on and that it would be well worth taking a few steps back.

We had a big discussion about windows. Given the heat loss of even the best windows relative to the highly insulated walls would I consider reducing their number...? what about quad glazing? In the end I did cut back on the number and size of some and briefly considered quad glazing but concerns about the loss of optical quality brought me back to triple-glazing. No matter how lofty my goals for conserving energy, enjoying the beauty of the site took precedence.

At the end of the day we were down to an electric boiler to supply water for the radiant floor in the house. A fan-coil in the house with hot water from the electric boiler to supply hot air to the upstairs rooms. We’d circulate well water through the same coil for summer cooling and the same ductwork would serve to distribute ventilation air year round. The upstairs room in the garage would be served by its own fan-coil in a similar way. Separate Heat Recovery Ventilators with energy efficient motors (Nutech MAX Series 195ECM) would be installed in each building to exhaust stale air and supply fresh.

The “all electric” solution was favored because of the potential to use photovoltaics, whether now or later, to generate a significant amount of the energy demand. I had anticipated this approach by orienting the long sides of the house and garage to face due south, including the large 45 deg. garage roof slope. A solar water heating system (www.thermo-dynamics.com) would be used to supply much of the domestic hot water and a “Contraflow Masonry Wood Heater” (http://heatkit.com) would make use of wood from the site to supply radiant heat, ambiance and baked bread to the Dining Room. On the back side of the masonry heater a more conventional wood-burning Rumford fireplace would warm the Living Room.