Learn the facts: Air conditioning and its effect on fuel consumption

What is the issue?

Using a vehicle’s air-conditioning system increases fuel consumption.

What do I need to know?

  • Most vehicle air conditioners (a/c) require engine power to operate. Of all auxiliary power requirements, a/c system use has the greatest impact on fuel consumption.
  • Using the a/c can increase fuel consumption by up to 20% because of the extra load on the engine. The a/c load depends on the vehicle’s interior size, the outdoor temperature and other operating conditions.
  • In the winter, vehicles use the heat from the engine to warm the cabin air. However, if the defrost setting is selected, the a/c system may also be engaged automatically to keep the windows from fogging.
  • Manufacturers are developing more efficient a/c system technologies and control strategies to reduce the impact of an a/c system on fuel consumption. For example, some manufacturers have introduced electric a/c systems to improve vehicle fuel efficiency.

How can I help?

  • Chill out and turn it off!
    Consider whether you really need the a/c for cooling. If not, turn it off!
  • Hit the re-circulation button!
    Consider using the “re-circulating” function of your a/c system. This method requires less energy because you are cooling only the air already in your vehicle, not bringing in warmer outside air to be cooled.
  • Let the air flow!
    Consider using the flow-through ventilation when you are on the highway, and open your windows and sunroof while driving in the city.
  • Be cool, and don’t over air condition!
    Just as you would at home, adjust your thermostat settings. Aim for comfortable – not cold.
  • Find a little shade!
    Your vehicle will require less cooling from the a/c at start-up if it is parked in the shade. If a shaded area is unavailable, using window shades will help to decrease the heat intake of your vehicle when it is parked. Also, don’t use the a/c when you first start your vehicle. Instead, open the windows for the first few minutes, and allow the hot air to escape.
  • Be a knowledgeable buyer!
    Be sure to ask if a vehicle has an a/c system with an “econo” mode or smart controls that help reduce fuel consumption.
  • Shut the a/c off after the windows are defrosted!
    In newer vehicles, the defrost setting automatically uses the vehicle’s a/c system to keep the windows from fogging. After the windows are clear, turn the a/c off and adjust the heater settings.

What are the costs?

The table lists the estimated fuel costs and CO2 emissions associated with a/c use.
Annual distance driven using a/c Annual increase in fuel consumption with a/c use Fuel cost of a/c use over 10 yrs CO2 emissions from fuel used for a/c over 10 yrs
If your a/c uses
1 L/100 km
If your a/c uses
2 L/100 km
If your a/c uses
1 L/100 km
If your a/c uses
2 L/100 km
If your a/c uses
1 L/100 km
If your a/c uses
2 L/100 km
14,000 km 140 L 280 L $1,526 $3,052 3,220 kg 6,440 kg
12,000 km 120 L 240 L $1,308 $2,616 2,760 kg 5,520 kg
10,000 km 100 L 200 L $1,090 $2,180 2,300 kg 4,600 kg
8,000 km 80 L 160 L $872 $1,744 1,840 kg 3,680 kg
6,000 km 60 L 120 L $654 $1,308 1,380 kg 2,760 kg

Note: For illustrative purposes, 10-yr figures are based on a fuel price of $1.09/L and CO2 emissions of 2.3 kg/L of gasoline.


With more than 20 million passenger vehicles on the road in Canada, the potential for savings from reduced a/c use is substantial!