Thermal insulation window films

Thermal insulation window films are used to reduce heat loss through existing glazing. Films of this type are mainly applied in buildings with older window systems, where replacing the entire window joinery is not planned or is not economically justified. Depending on the age and construction of the glass unit, the possible correction of the thermal transmittance coefficient U is usually between 5% and even 20%.

How do thermal insulation films work?

Thermal insulation films work on the principle of a low-emissivity coating. After installation on the glass surface, they reflect part of the heat radiation back into the room instead of allowing it to pass outside. As a result, they reduce heat loss without interfering with the window structure.

Unlike factory Low-E coatings, which are located inside the insulated glass unit, thermal insulation film is a retrofit solution applied to existing glazing. This means it can supplement existing glass, especially where modern insulation technologies were not originally used.

On which windows will the effect be noticeable?

Thermal insulation films achieve the greatest effectiveness on single glazing, which has no low-emissivity coatings or gas-filled chambers. In this case, the film acts as the only layer limiting heat emission, so its impact on reducing energy loss and improving thermal comfort directly near the window is the most noticeable.

Another group where the effect of the film is clearly visible is older double-glazed units, especially those produced without modern Low-E coatings. An additional low-emissivity layer in the form of film effectively supplements the structural limitations of such glazing, reducing heat escape and improving its insulating properties.

In the case of new triple-glazed windows with a very low U-value, the benefits of using film are small or practically unnoticeable. This type of glazing already uses advanced insulation technologies at the production stage, so the film cannot significantly improve parameters that are close to the limits of technical possibilities.

Energy-saving window films

Low-E energy-saving films also have an important impact on the comfort of using rooms, not only on the thermal parameters of the window itself. By reducing the so-called “cold glass” effect, they reduce the perceived cold radiation near the pane, which results in smaller discomfort zones next to windows and allows more efficient use of the space near external walls.

What is the thermal transmittance coefficient?

In simple terms, it is a value that describes the amount of heat lost through one square metre of glass when the difference between the temperature outside the room and the temperature inside the room is 1 Kelvin. The lower the coefficient, the better the protection against unwanted heat loss.

Can the thermal transmittance coefficient be improved?

Yes. This can be done by replacing the windows with more modern ones with a better, meaning lower, thermal transmittance coefficient, or by correcting the coefficient on existing glass, for example by installing Eco-Termic thermal insulation film.

FAQ – Frequently asked questions

Can thermal insulation film replace window replacement?

No. The film is a solution that corrects the parameters of existing glass, not a full replacement for modern window joinery.

How much can the U-value realistically be improved?

Depending on the age and type of the glass unit, the improvement may range from a few to a dozen or so percent. The best results are achieved on older windows.