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Personal: Residential

Gas Heating Terms and Conversions

The heating capacity of gas-heating appliances is commonly expressed in kilowatts (kW), British thermal units (Btu) or megajoules (MJ).

1 kW = 3413 Btu = 3.6 MJ

The gas industry still commonly uses Btu/h for rating heating appliances, but newer equipment should also be labelled with the equivalent rating in kWh. The heating capacity of electric heating systems is usually expressed in kW. Most home heating appliances have capacities between 40 000 and 150 000 Btu/h (about 12 kW to 44 kW).

Energy consumption is measured in kilowatts per hour (kWh), British thermal units per hour (Btu/h) or megajoules per hour (MJ/h).

1 kWh = 3413 Btu/h = 3.6 MJ/h

Natural Gas

Consumption of natural gas is measured in cubic metres () or cubic feet (cu. ft.). This is the amount registered by your gas meter and recorded by the gas utility. The unit of measurement used in billing is inconsistent across Canada. If the units on your utility bill differ from those on your meter, use one of the following conversions:

  • To convert cubic metres to cubic feet, multiply by 35.3
  • To convert cubic feet to cubic metres, multiply by 0.028
  • One cubic metre of natural gas contains 37.5 MJ (35 500 Btu) of energy.


Consumption of propane is usually measured in litres (L), with propane having an energy content of about 25.3 MJ/L.

In general, the same principles apply to propane as to natural gas, with slight differences in efficiencies. Propane has a lower hydrogen level than natural gas. About 3 percent less energy is tied up in the form of latent heat with propane systems than with natural gas. This means that conventional and standard-efficiency propane furnaces can be expected to be slightly more efficient than comparable natural gas units. On the other hand, propane's lower hydrogen content makes it more difficult to condense the combustion products, so that a propane-fired condensing furnace will be less efficient than the same unit fired with natural gas.

Certification and Standards

All gas-fired appliances sold in Canada must conform to safety standards established by the Canadian Standards Association (CSA). As proof of compliance, they must also be certified by an independent body accredited by the Standards Council of Canada, such as CSA International, Underwriters Laboratories Inc. (UL), Underwriters' Laboratories of Canada (ULC), Intertek Testing Services NA Ltd., or OMNI-Test Laboratories Inc. Before purchasing your heating equipment, be sure it carries a certification label from one of these agencies.

The CSA standards for gas-fired furnaces and boilers also require compliance with the efficiency levels currently prescribed in the federal Energy Efficiency Regulations.