October 15, 2024, 3:37 pm | Read time: 4 minutes
As retrofit insulation, special reflective foil behind the heating system is intended to reduce heat loss by up to 50 percent. Is silver foil really worthwhile as insulation?
Aluminum foil is used in the kitchen to keep food warm, among other things. The foil has the property of reflecting light and heat. The properties of silver foil are also useful on car windows in winter to protect against frost at night. Reflective foil for heating works on a similar principle and is usually equipped with an additional insulating layer. If you attach this behind the radiator, less heat should be lost through the wall. myHOMEBOOK asked an expert whether it is worth investing in reflective foil and how to install it.
Overview
What is reflective foil?
Reflective foils for radiators are thin insulating panels coated with aluminum. They are stuck to the wall behind the radiators and are intended to provide additional insulation.
Advantages of reflective foil
One advantage of reflective foil for radiators is that it is easy to install. Consumers simply have to cut the thin films to the right size. They then clean the wall behind the radiator and apply the foil. If space is limited, it is advisable to remove the radiator for installation. The cost of the foil is also relatively low, ranging from 5 to 15 euros per square meter.
Disadvantages of reflective foil
Unfortunately, insulation with aluminum or reflective foil can also have disadvantages. If the insulation panels are not installed correctly, mold can form between the wall and the foil. This can only be prevented if the reflective foil is glued without any gaps. However, this is often difficult to achieve in narrow radiator niches.
How do you avoid mold forming behind the foil?
With reflective foil, mold can always form behind it, especially if it is attached to an external wall. To prevent mold growth, the film should be applied as flush as possible so that there are no air pockets. You can use a paint roller or squeegee for this.
How do you apply the foil?
In general, you should follow the instructions included in the package when applying the reflective foil. As a rule, the following steps are necessary:
- Measure the area behind the radiator.
- Cut the film to size, preferably slightly larger than the radiator.
- Allow for cut-outs for the bracket and pipes of the heating system.
- Remove dust and dirt from the wall before fitting.
- Now press the foil – if it is self-adhesive – onto the wall. A spirit level can help to ensure that the foil is straight. A second person is also helpful when applying the foil. If the foil is not self-adhesive, you can use a mounting adhesive.
When sticking it down, make sure that no air bubbles form. It is best for one person to hold the foil firmly on the upper side and for the other to smooth it downwards. Experienced DIY enthusiasts can also dismantle the radiator beforehand for easier access. This is a little more time-consuming but makes it easier to apply the foil.
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What does the expert say?
Frank Ebisch, press spokesman for the German Central Association for Sanitary, Heating and Air Conditioning, has to temper expectations. In practice, the application of reflective foil behind the heating has hardly proven itself. “If it consists of pure aluminum foil, the insulation effect on the wall is practically unchanged. The radiant heat emitted by the radiator can still be reflected.”
However, if the foil contains an insulating layer, things look better. “In relation to a very poorly insulated house, a saving of just 4 percent can be achieved here if all radiator niches are equipped accordingly. If the wall is better insulated, you might save another 1.5 percent,” explains the professional. Ebisch notes that with modern construction methods, which lack radiator niches with thin walls and feature significantly higher insulation standards, such foil is not cost-effective.
Tip: If your home has a poor energy balance, it may be worthwhile retrofitting insulation with insulation boards on the exterior wall. However, they should be installed only by skilled DIYers or professionals.