Does Turning Off Air Conditioning in Your Car and Opening the Windows Save Fuel?

That depends

(SAE: Warrendale, PA) -- Consumers continue to be concerned about the fuel consumption of their vehicles, yet many are unaware of the effect that accessories have on fuel consumption. Vehicle air conditioning (A/C) is one of the highest energy-consuming accessories and has become standard equipment for vehicles.

Members of the SAE International Interior Climate Control Standards Committee authored an article discussing automobile fuel consumption and A/C. The choice of how you use (or don’t use) the A/C involves your and your passengers’ comfort. There are many factors that effect how much fuel is used, including the specific vehicle fuel use (MPG rating) for the type of driving, as well as temperature and humidity conditions.

The energy required to provide comfort in a vehicle depends on many factors, such as the load on the A/C system, which is a function of the fan setting, the outside ambient temperature and humidity, and the speed of the vehicle, among other variables. The fuel consumption of the A/C will vary greatly depending on the weather conditions and also on traffic patterns typical of a given city.

So can you save fuel by not running the A/C? That depends.

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Comments

Word usage, and more

the word effect is a noun, the word affect is the verb. Effect was used several times as a verb in this article. http://web.ku.edu/~edit/affect.html

In another comment, the upside down graphs are harder to comprehend, why was mpg used in lieu of amount of fuel?

It has been know for a long time that driving with the windows down uses more fuel than using the airconditioner. I guess you are trying to say that if the AC unit is run at high cooling and fan it uses more fuel and may be about even to driving with the windows down. Do many run low fan, recirculate, in lieu of high fan and no recirculate? I usually run recirculate when I wnat to cool down in a hurry.

The noise level increases considerably with the windows down. If the temperature outside is cooler than your mid-90's example, then a mix might be used. At highway speeds, there rarely is anyone driving with the windows down due to the noise. Way back when I was a child, AC units wern't in every vehicle, and we had to run with windows down.