Sun protection film for windows: lower the room temperature in summer

If the sun shines on your windows for hours in the summer, it heats up the living rooms unhindered – provided there are no air conditioning units. The sun’s rays act like a kind of heater that generates warm air. The problem with this is that the overheated rooms hardly cool down noticeably overnight, so that sleep is negatively affected. And working during the day too, if you work from home. In order to lower the room temperature, it can be useful to attach a sun protection film. This article explains the advantages and disadvantages of the purchase.

The pros and cons of solar control film

A reflective one consists of several layers that ensure that a large part of the sun’s rays are reflected – in other words, less heat gets inside the apartment. The darker a film, the greater the heat protection. Conversely, this also means that less light can penetrate through the windows. In addition: If the sun protection film is not removed in the cold autumn and winter months, the rooms have to be heated more from the inside. So before you decide on a sun protection film, you should carefully weigh up the advantages and disadvantages. The following table lists the most important (criticism) points again:

Inside or outside? How to attach the foil

Depending on the type of window and glazing, you should use the reflective attach either outside or inside – if the windows are only single glazed, even from both sides. Attaching it to the inside of safety glass or skylights has the advantage that the film is not exposed to the weather and is therefore more durable. Nevertheless, it is recommended for multi-glazed windows to attach the sun protection film on the outside (if suitable). This reflects the sun in front of the glass so that it does not heat up and does not give off heat to the interior. However, before you get to work, you will need other supplies, such as a window cleaner and water, dish soap and a spray bottle, a tape measure or ruler, some tape and a cutter and a clean, lint-free cloth.

The following video explains step by step how you can attach a sun protection film to the window yourself.

Sun protection film in the test: That’s what the experts say

Stiftung Warentest has also addressed the question of how well sun protection films really work in practice. A total of eleven different models from different manufacturers were tested. The result was that most of the slides finished with “good” or “satisfactory”. The biggest differences were in terms of handling and weather resistance. But what is even more important: Highly reflective sun protection films actually only let 13 to 20 percent of the sun’s rays into the room. Nevertheless, Warentest also sees a disadvantage in the fact that the rooms appear darker and heating costs could be higher in winter – and comes to the following conclusion: “Dark sun protection films are particularly suitable for very overheated rooms in the attic.”

In addition, the consumer organization is convinced that the strong reflections of a sun protection film on sloping roofs would not disturb the surrounding neighbours. Therefore, the general recommendation after the test series is: “For living rooms with vertical windows, less reflective films are the better choice. They don’t reflect as much and are less annoying to residents. Nevertheless, they block 55 to 60 percent of the sun’s energy Overheating hours in the room by more than a third. The view is hardly clouded, colors appear natural.”

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