Electric Heating - Environmental and Efficiency Aspects

Environmental and Efficiency Aspects

The efficiency of any system depends on the definition of the boundaries of the system. For an electrical energy customer the efficiency of electric space heating is 100% because all purchased energy is converted to building heat. However, if the power plant supplying electricity is included, the overall efficiency drops. For example, a fossil-fuelled power plant may only deliver 4 units of electrical energy for every 10 units of fuel energy released. Even with a 100% efficient electric heater, the amount of fuel needed for a given amount of heat is more than if the fuel was burned in a furnace or boiler at the building being heated. If the same fuel could be used for space heating by a consumer, it would be more efficient overall to burn the fuel at the end user's building.

In Sweden the use of direct electric heating has been restricted since the 1980s for this reason, and there are plans to phase it out entirely - see Oil phase-out in Sweden - while Denmark has banned the installation of electric space heating in new buildings for similar reasons. In the case of new buildings, low-energy building techniques can be used which can virtually eliminate the need for heating, such as those built to the Passivhaus standard.

In Quebec however, electric heating is still the most popular form of home heating. According to a 2003 Statistics Canada survey, 68% of households in the province uses electricity for space heating. More than 90% of all power consumed in Quebec is generated by hydroelectric dams, which have lower greenhouse gases emissions than thermal power stations and the low and stable rates charged by Hydro-Québec, the provincially-owned utility.

To provide heat more efficiently, an electrically driven heat pump can raise the indoor temperature by extracting energy from the ground, the outside air, or waste streams such as exhaust air. This can cut the electricity consumption to as little as 20% of that used by resistive heating and thus reduce the environmental impact.

Electrical space heating can still be economic where electricity supplies are low-cost. Where the primary source of electrical energy is hydroelectric, nuclear, wind, or other carbon-free source, it may not be practical to exploit that resource directly in heating applications but grid electricity can be conveniently used. Electric space heating is useful in places where air-handling is difficult, such as in laboratories.