How to stay cool without draining your wallet

A renowned federal agency has proven it costs more to be cool.

According to a recent report from Oak Ridge National Laboratory, the testing arm of the U.S. Department of Energy, cranking up your vehicle’s air conditioning system increases gas consumption.“Under very hot conditions, air conditioning use can reduce a conventional vehicle’s fuel economy by more than 25 percent,” said Bo Saulsbury of the lab’s center for transportation analysis. “And driving on the freeway with open windows can increase wind resistance, making your vehicle use more energy to push through the air.” ORNL, famed for developing the atomic bomb, tested a variety of conventional and electric vehicles. The electric motor found in hybrids and all-electric vehicles may lower fuel economy further.

Despite the alarming statistics, Saulsbury assured drivers they don’t have to choose between comfort and fuel economy. Basic precautions–like making sure your tires are properly inflated–help keep vehicles running efficiently.Parking in the shade or using a sunshade can prevent cabin temperature from spiking.“Getting hot air out of the cabin first will put less demand on the air conditioning and help your vehicle cool faster,” Saulsbury said. Using a fan that plugs into your car’s adapter won’t impact fuel economy because it runs off the battery, he said, but it won’t create cool air.The mileage drain is an interesting conundrum, as some aspects of hot weather can also benefit a vehicle’s fuel efficiency, Saulsbury said.“In hot weather your engine warms up faster, summer grades of gasoline can have slightly more energy and warm air causes less aerodynamic drag than cold air,” he said. “As time goes on and systems get more efficient, they may not have as much an impact on fuel economy.”Saulsbury offered the following tips for getting the best fuel economy while using the air conditioner or driving with the windows down:

• Roll down windows lower driving speeds and use the air conditioning system at freeway speeds.
• Set your the climate control system at a comfortable temperature but not so low as to burden the engine.
• Park in the shade or use a sunshade to keep the cabin as cool as possible.
• Vent the passenger cabin. While driving at low speeds, open the windows to remove hot air–it cools off the cabin faster and places less demand on the vehicle.