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Personal: Residential

Energy Efficiency Terms

Some impressive improvements have been made in heating systems in recent years, and there is a wide range of equipment on the market. You will be using your heating system for a long time, so it is important to do your homework before you improve what you have or buy a new one. Investigate all your options thoroughly. They may seem quite bewildering because of the wide range of equipment and energy sources available.

About 60 percent of the energy required to run the average home is used for space heating. If your present heating system is costing too much to operate, is performing inconsistently or is in poor condition, or if you are planning to buy a new home, you are likely to choose, change or upgrade a heating system. A smart decision about heating can significantly reduce the cost of running your home and can make your home more comfortable.

Here are some basic concepts that will help you understand your options.

Heat loss – All fuel-burning systems (natural gas, oil, propane, wood) lose heat because of stopping and starting, cold start-up, incomplete combustion, heat carried away in combustion gases, and warm house air drawn up the chimney. The extent of these losses determines the efficiency of a furnace or boiler, given as a percentage indicating the amount of original heat that actually warms the house. Electric space heating equipment, which uses electric resistance heating, is typically 100 per cent efficient because all the electrical energy used is converted into heat and there are no combustion losses through the chimney.

Steady-state efficiency – measures the maximum efficiency of the furnace after it has been running long enough to reach its peak operating temperature. This is an important standardized testing procedure that is used by a serviceperson to adjust the furnace, but the figure it gives is not the efficiency achieved by the furnace or boiler in actual use over the course of a heating season. Think of the difference between the fuel consumption figures for city and highway driving published for cars. Steady-state efficiency in a furnace is like the best fuel mileage you can get when driving on the highway.

Seasonal efficiency (also known as the annual fuel utilization efficiency (AFUE) – 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 milder weather at the beginning and end of the heating season. This figure is useful because it is a good indication of how much annual heating costs will be reduced by improving existing equipment or by replacing it with a higher efficiency unit.

Typical Heating System Efficiencies and Energy Savings.