It is often said that black cars heat up much more than whites in summer. This phenomenon is generally known and is usually explained with the physical property of colors. In theory, this seems logical because black surfaces absorb more energy and thus become hotter, while white surfaces reflect a large part of the light and thus store fewer heat. But what does that look like in practice?
The ADAC test: The color makes no significant difference
Although the temperature difference of the outer surfaces of black and white cars is considerable, the question arises as to how this affects the temperature in the interior. Tests of the ADAC and other organizations show that the color of the paint in the interior has less influence than is often assumed. The actual temperature difference inside a black and a white car is only about five degrees.
Physical explanation: Why dark colors absorb more energy
The physical explanation behind the stronger warming of black surfaces lies in the absorption of radiation energy. Black surfaces absorb almost the entire spectrum of the visible light and convert it into heat, while white surfaces reflect the most light. This explains why the paint surface of a black car becomes hotter than that of a white one.
But the temperature inside a car is determined by many other factors. Therefore, the difference in the perceived heat in the interior between black and white cars is often less drastic than you would expect.
The reason for this is that the heating of the interior is mainly influenced by the size of the window surfaces, the sun’s radiation and the choice of materials in the interior. Even if black paints absorb the sunlight more, the majority of the heat energy gets through the windows into the vehicle interior. The thermal energy penetrating into the vehicle is distributed throughout the interior, and the color of the body has little influence on this process. The interior plays an important role here: Dark leather seats, for example, heat up faster than light fabrics and contribute to the subjective perception of a higher temperature.
Window areas and sunlight as decisive factors
The size and alignment of the window surfaces of a vehicle are essential factors for heating the interior, as the ADAC continues. Uncoated windows let a considerable amount of solar energy penetrate the vehicle, which increases heat development. In contrast, heat protection glazing or tinted slices can reflect a large part of the incident sunlight and prevent the car from heating up excessively.
Another aspect is the stem angle of the sun. Vehicles that have long been parked in the immediate vicinity heat up heavily regardless of the paint color. The ADAC shows that the temperature in the interior can rise to up to 50 degrees Celsius in a closed car within just 20 minutes – regardless of whether the vehicle is white or painted in black. Here the stand of the sun and the alignment of the car play a larger role than the color of the paint.
Practical tips: How the heat in the car can be reduced
Regardless of the paint color of a car, various measures can be taken to reduce heat development in the interior. Tinted slices or sun protection mats are effective means of reducing direct sunlight. The use of sun protection films or the installation of heat protection glazing can also reduce the amount of incident sunlight and thus keep the interior cooler, as it continues.
Another proven means is to park the vehicle in the shade if possible or to cover it with sun protection mats in order to minimize direct radiation. Airs before starting and using the air conditioning while driving are also important measures to quickly reduce the temperature in the vehicle.
D. Maier / Redaktion Finanzen.net