Window films and secondary windows appear to be ways to save energy quickly and easily. What exactly is it like and how much profit can be made?
With a simple film of a few euros for your windows you can avoid a lot of heat loss and save money. The research agency TNO recently came to this conclusion after a study. “The sheets have been in stores for decades, but few people use them. Unknown makes unloved,” says TNO researcher Erik Carton.
Window films are particularly effective for single glazed houses or houses with older types of double glazing. This mainly concerns (old) rented houses. A lot of heat escapes from these types of houses. As a result, residents have to burn a lot in the winter to avoid table nickel plating. Can we no longer try to keep that heat inside, TNO wondered.
Film on windows against the cold: does it help?
“We calculated the effect of window film and a secondary window and what a good distance from the window is,” the research agency said. The study showed that a secondary window made of wood slats and window film means that single-pane windows let in up to 35 percent less heat. Double glazing is 20%.
You can save energy quite easily in a very short period of time. Those few euros are really worth it.
Cardboard: “Applying the window film takes fifteen minutes per window. You can leave the film in place after the winter, as it also helps keep out the summer heat. The film also lets through good light. I shot two picture of a window with and without film, you only see a small difference. You can easily see through a window with film.”
The sheet can also be beaten. “If you have cats and small children, the film may not last all winter. But you can bang the window without breaking the film.”
Sheet insulating piece less effective than triple glazing
Lars Boelen, energy expert and savings guru, also calls window film “a fantastic solution”. “You can save energy quite easily in a very short period of time. Those few euros are really worth it, I would really recommend it. You’ll have it out in no time.”
According to Milieu Centraal, window film insulates much less well than HR++ or triple glazing. But the purchase of such windows requires investment. And, the information organization adds however, insulation window film is very different from anti-vision film. It does not isolate. If you opt for a more expensive variant, such as window film (around $150 per square metre), it’s best to get new windows, according to Milieu Centraal.
How do you create a secondary window and what can you save with it?
In addition to window films, TNO has also conducted research into secondary windows. You can easily make them yourself with materials that you can buy at the hardware store. “That will cost you about an hour per window. You have to measure and saw and screw,” says Carton.
Then you create a frame between which you apply window film. You do this with two insulating layers of air. “Although even one roll of film is enough,” says Carton. It’s also important pay attention to the distance at the window – the smaller the better. Ventilation is also required.
According to Milieu Centraal, you can save 13 euros per square meter per year with such a front window. That equates to 500-800 euros a year, calculated TNO. Carton: “I recently went to check out the Praxis and the Gamma. The foil has been out of stock for weeks, while last year it barely sold.”
In this video, Erik Carton of TNO explains how to make a secondary window.
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