Window film for insulation

Ergates

Looking at things we can do to improve the insulation on our house.   Using a thermal camera I can see that we appear to be losing a quite a lot of heat through the windows.  Whilst replacing the windows with better insulated units would be the long term solution to this it would like cost tens of thousands (we have a lot of windows), which we don't have right now.

One thing I've read about is installing film on the inside of the windows which can help reflect heat back into the room.  Obviously wouldn't be as good as better windows, but way more affordable.

Whilst searching for information on the web pretty much all the "Do window films actually work?" questions seem to be hosted on websites of the companies who sell the stuff, so not exactly unbiased!

Has anyone done this and does it actually work?   

Grenage

It won't have any real impact, no.

TELLIT01

Film is sometimes added to windows in commercial buildings to keep the heat out, but that requires a highly reflective film which also reduces the amount of light passing through.  Putting it on house windows to prevent heat loss would potentially mean that you couldn't see out of them.

grumbler

Grenage said:

It won't have any real impact, no.

I am no expert and don't know how you define 'real', but for low-E glass, very common, they claim up to 50% reduction in heat loss via radiation. I don't see  why film can't have about the same efficiency in this respect.

Of course, film is less practical and will deteriorate with time.

sk2402005

Window film only really works as reflecting the energy from the sun away, and will be much less effective at reflecting the heat back into the house.

There are products that stick to tehe frame rather than the window which do work by trapping the air, but its quite fragile, and can trap mositure between the window and the film.

https://www.amazon.co.uk/tesa-UK-Thermocover-Insulating-Transparent/dp/B0038JE7WW/ref=asc_df_B0038JE7WW/?tag=googshopuk-21&linkCode=df0&hvadid=231908893094&hvpos=&hvnetw=g&hvrand=9800976553280770775&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=1007196&hvtargid=pla-420142246222&psc=1&th=1&psc=1

Ergates

The claims they seem to be making - reduce heat loss through windows by 25-30% did seem a bit "optimistic",