What is the quickest way to cool down a roasting hot car?

By dpa | 7 July 2017


BERLIN: On sunny days, the inside of a car can get very hot, very quickly. This is in large part due to the car's many glass surfaces, particularly the windscreen.

"Windscreens alone have become much bigger in recent years, and in some models the glass continues well into the roof," notes Thomas Klein from the German national autoglass association.

The windscreen tends to be the main culprit when it comes to letting in heat, since it can usually only be tinted to a limited extent. "Cars can have darker tinted glass, such as privacy glass, starting at the B-pillar," explains Klein.

The front window and the front side windows, on the other hand, need to have a light transmittance value of at least 70 per cent.

Women walking under bruning hot sun at Palivillion Jalan Bukit Bintang


According to the autoglass manufacturer Saint-Gobain Sekurit International, standard green-tinted windows let in 65 per cent of heat from outside, while in the case of special heat-resistant glazing, this can drop to just 40 per cent.

Once a car heats up, the driver has several ways to lower the temperature. "The first step is to open the windows and doors to let the car air out before starting up and driving off," says Alexander Ahrens from VCD, a major German automobile club.

Once they are ready to get going, drivers should close the windows and cool off the interior with the air conditioning on high for about five minutes. "Afterwards, put the air conditioning on a lower setting - and never direct the cold air directly onto your face," advises Ahrens, since this could lead to you catching a cold.

In cars without air conditioning, the windows should be opened slightly and the ventilation system should be put on the lowest setting to allow for better air circulation.

If they ignore the heat in the car, drivers should be prepared to deal with considerable physical impairments. "A hot car can quickly reach temperatures of well over 50 degrees," explains German traffic safety expert Dr Matthias Graw. "This has a direct effect on one's concentration and reaction times."

People who are prone to high blood pressure or circulatory problems should be especially careful when driving on hot days and should take frequent, short breaks in shady places. It is also important to stay hydrated.

"It is best to drink small sips of water more regularly than a larger quantity all at once," says Graw. He also advises drivers who know they will be driving on a hot day to take two to three litres of fluids with them, and to watch for dark urine when taking a bathroom break, as this is a potential sign of dehydration.

If the interior cools down too much, the hot outside temperatures can be a shock to the body when you get out of the car. Ahrens therefore recommends that the temperature difference between the car's interior and the outside temperature should be no more than three degrees, especially when approaching the end of a trip.

An easy and effective way to stave off the heat is to place a simple sheet of corrugated cardboard behind the windscreen when the car is parked. "In addition, the dashboard, steering wheel and seats can be covered with a cloth," notes Ahrens.

Window shades on the rear side windows can provide extra heat protection, but this also hinders visibility. A better idea is to opt for factory-installed heat-resistant glazing when buying a new car, advises Ahrens.

If the windscreen has to be replaced because of glass damage, it is also worthwhile to switch over to a heat-resistant glazing. "In many cases, this is not much more expensive," he says. "For vehicles like the Audi A4 or a BMW 5 Series, for example, a heat-resistant windscreen only costs about a third more."

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