Coefficient of performance (COP) A measure of a heat pump's efficiency. It is determined by dividing the energy output of the heat pump by the electrical energy needed to run the heat pump, at a specific temperature. Based on Natural Resources Canada, 1995. Seasonal energy efficiency ratio (SEER) A measurement of the cooling efficiency of the heat pump over the entire cooling season. It is determined by dividing the total cooling provided over the cooling season in BTU by the total energy used by the heat pump during that time in watthours. The SEER is based on a climate with an average summer temperature of 28°C. Based on Natural Resources Canada, 1998. Crawl space A dirt or gravel space below the main floor, 1 to 2 metres high, that is not insulated, heated or ventilated. Crawl spaces are usually found in homes built before the early 1940s or much earlier. Close