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A heat pump is an electric device that supplies a building's demand for thermal energy applications without the combustion of fossil fuels. Five applications consume secondary energy in a home: space heating, water heating, space cooling, lights, appliances. Canada's energy department estimates that 15.3 million households (all dwelling units) consumed 405 billion kWh in 2022 (1,461 PJ) of which the first three thermal applications consumed 328 billion kWh (81% of energy). These households emitted 56 billion kg (56 Mt) of carbon, of which thermal applications emitted 48 billion kg (87% of emissions). This means the average household (each dwelling unit in Canada) consumed 26,401 kWh of energy, of which 21,307 kWh was for thermal applications (13 kWh per ft2), and emitted 3,627 kg of carbon, of which 3,148 kg was from thermal applications (2 kg per ft2). This will vary depending on geographic location, dwelling size, design, number of occupants, etc. What are the options? (before considering any supply option, follow the Rule of 3C as much as possible) Heat pumps produce thermal heat from the heat in the air or in the ground / water. They consume conventional electricity to operate a compressor, pumps & motors, and the efficiency of a system is the ratio of energy produced vs the energy consumed to produce that output, rated as EER (energy efficiency ratio) or COP (co-efficient of performance). Air Source Heat Pumps (ASHP) funnel outside air through a coil where a compressor extracts the thermal energy for distribution inside the building. In summer, it absorbs the warmth from inside air for discharge outside, thereby providing space cooling. The efficiency of an ASHP declines with outdoor temperature and the exterior unit can be quite noisy, but the cost to install a unit is lower than other options and is suitable for renovations. Ground Source Heat Pumps (GSHP) bury pipe in the ground (horizontal loop or vertical borehole) to circulate a fluid that is warmed by the earth before it returns to a compressor that circulates the heat inside the building. In summer, the direction is reversed to take warm air out of the building for ejection into the ground. A Water Source Heat Pump uses the same process but relies on water as the heat source or heat sink. A GSHP is more expensive to install because of the cost to dig loops or boreholes (much lower in new construction before landscaping is finished) but it performs efficiently in any ambient temperature and makes no noise.
Government schematics show how ASHP & GSHP produce thermal energy for buildings. ASHP or GSHP will produce that 21,307 as dispatchable (no battery required) renewable energy. Depending on rated EER / COP, a system will require 7,000 to 11,000 kWh per year for operational power. If the grid electricity is generated from non-combustion sources, the dwelling would reduce annual carbon emissions by 3,148 kg. Heat pump technology offers many benefits to the building owner, the economy & the environment, but the industry needs to quantify its production of thermal output in kWh so consumers have a clear comparison of supply options. That measure would allow a PTC (Production Thermal Credit) or a T-REC (Thermal Renewable Energy Credit) to incent on-going operational efficiency and to avoid reliance on price-skewing installation grants. It would also allow a home to verify that it produces 21,307 kWh of renewable energy, compared to its annual consumption of 11,000 kWh (7,000 kWh for operating power plus an average of 4,000 kWh for lights & appliances), in order to be classified as NetZeroPLUS. |
