Energy Efficiency

Electric space heating equipment that uses electric resistance heating is typically 100 per cent efficient because all of the electrical energy used is converted into heat and there are no combustion losses through the chimney.Fuel-burning systems (natural gas, oil, propane, wood) lose heat for various reasons: transient operation, cold start-up,incomplete combustion, heat carried away in the combustion gases, and warm house air that is drawn up the chimney.

The extent of these heat losses determines the efficiency of the furnace or boiler, given as a percentage indicating the amount of original heat that actually warms the house. Steady-state efficiency measures the maximum efficiency the furnace or boiler achieves after it has been running long
enough to reach its peak operating temperature. This is an important standardized testing procedure that is also used by a serviceperson when adjusting the heating system, but the figure it provides is not the efficiency the equipment will achieve in actual use over the course of a heating season.

This is much like the difference between the fuel consumption figures published for cars and the actual consumption the car will achieve in its day-to-day performance. Seasonal efficiency takes into consideration not only normal operating losses, but also the fact that most heating equipment rarely runs long enough to reach its steady-state efficiency temperature, particularly during the milder weather at the beginning and at the end of the heating season. This figure, known as the Annual Fuel Utilization Efficiency (AFUE), is most useful to a homeowner, because it is a good indication of how much annual heating costs will be reduced by improving existing equipment or replacing it with a higher efficiency unit.

All types of heating systems come complete with their own jargon. If you are heating with electricity or are considering it, the better you understand the electric heating jargon, the better equipped you will be to make a wise heating system choice. The text box “Coming to Terms with Electricity”
presents some of the basics.

Coming to Terms with Electricity

Measuring up
Here are some common terms you will come across while exploring the option of heating with electricity. watt (W) – The watt is the basic unit of measurement for electric power. The heating capacity of electric heating systems is usually expressed in kilowatts (kW). One kW equals 1000 watts.
kilowatt hour (kWh) – One kWh is the amount of electric energy supplied by one kW of power over a one-hour period. When converted to heat in an electric resistance heating element,one kilowatt an hour produces 3.6 megajoules (MJ) or 3412 British Thermal Units (Btu) of heat.

ampere (A) – Electric flow is called current and is expressed in amperes. The short form is A, although amp is also used.

volt (V) – A volt is the basic unit of measurement for voltage or potential difference. Voltage causes an electric current to flow.

Putting it all together
A watt is the power you get when one volt of potential difference pushes one ampere of current. Expressed mathematically
Wattage = voltage x amperes (W = V x A)