Alberta, or any other part of Canada, needs to freeze in the dark on a windless day for lack of heat from natural gas even if the temperature is -30°C. Ground and air-source heat pumps have been warming Canadian buildings without carbon emissions for decades. Beginning in the 1980s, engineering firms such as Mancini & Associates Ltd. (Toronto, ON) and Geotility (Kelowna, BC) have been designing and installing ground-source heating and cooling systems for homes, schools and commercial buildings. Their systems are less expensive and more reliable than heating with fossil fuels.
Ground-source systems use solar heat energy stored in the ground. The top two metres of the ground fluctuates with air temperature, but below two metres and down a few hundred more, ground temperature is constant, equal to the average air temperature. In Castlegar, BC, that’s 10°C. Even better, while fossil fuel systems can never exceed 100% efficiency, ground-source systems typically are over 300% efficient because the systems extract more than three units of free, useful, heat energy from the ground for every unit of electric energy purchased to operate the systems’ components.
Air-source heat pumps extract heat from outdoor air. They have lower capital costs than ground-source systems. Newer air-source heat pumps, rated for cold climates, must achieve a minimum of 180% efficiency at -15°C.
Heat can be efficiently extracted from rivers, lakes, oceans, and even abandoned mines filled with groundwater. The kilometres of water-filled abandoned mines underneath Rossland, B.C. contain sufficient energy to heat every home and commercial building in town.
None of this is new. While the first step in heating or cooling a building is always to minimize its energy demand; heat pumps, both ground and air-source, can deliver base load heating regardless of time of day or wind as they have in my home since 2008, Castlegar’s city hall since 2007, and Selkirk College’s Mir Centre and 10th Street student residence for over a decade.Robert M. Macrae
Castlegar, BC
