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Business: Residential

EnerGuide Room Air Conditioner Directory 2011

How to Calculate Air-Conditioning Costs (Worksheet 2)

The cost of operating a room air conditioner varies according to several factors, including the following:

  • the EER and cooling capacity of the air conditioner;
  • the temperature setting you use;
  • whether you run the fan on "continuous" or "auto" mode;
  • which of the unit's features you choose to use;
  • how often you use the unit;
  • the price of electricity; and
  • the weather.

To estimate the energy cost of a specific room air conditioner before you buy it, multiply the unit's energy consumption by the price of electricity in your region. Worksheet 2 (below) will help with this calculation.

Worksheet 2 Example

This worksheet calculates the cost of running a room air conditioner with a cooling capacity of 10 000 Btu/h in Toronto, Ontario. Follow along and enter the numbers for your air conditioner in the spaces provided.

Almost 400 models listed in this directory meet the ENERGY STAR® specifications.

Step 1

Determine the unit's approximate energy consumption.

Go to the section “Energy Consumption in kWh by Province” and find your province and the cooling capacity you require. Then determine your air conditioner's approximate energy consumption by consulting the column for the city nearest you. Energy-consumption figures are provided only for the most and the least energy-efficient units at a particular cooling capacity. For example:

City Cooling Capacity Energy Consumption (in kWh)
For Model With
  Highest EER
Lowest EER
Toronto 10 000 513 628

Step 2

Determine the price of electricity in your area.

Check a recent utility bill for the basic cost of electricity in your area. Be sure to include distribution and generation costs as well as taxes. If you don't have a bill handy, use a typical cost of 10 cents per kWh.

Price Of Electricity

Step 3

Do the calculation.

Use the following formula to estimate annual and lifetime energy costs. Do the calculation for the most and the least efficient units to appreciate the cost difference, annually and over a unit's typical lifespan of 10 years.

Approximate Energy Consumption (kWh per cooling season)   Price Of Electricity (perkWh)   Annual Operating Cost   Lifetime Operating Cost Or "Second Price Tag" (multiply annual cost by 10)
EER 12.0     Most Energy Efficient
513 x $0.10 = $51.30 $513.00
Step 1   Step 2   Step 3  
x =  
EER 9.8     Least Energy Efficient
628 x $ 0.10 = $62.80   $628.00
Step 1   Step 2   Step 3  
x =  

Forward the relevant information to the section My Shopping Notes.

In this example, buying the most energy-efficient unit means a lifetime savings of $115 – or more, if the price of electricity increases.

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