Window foil

[quixoticgeek]

My bedroom has one wall which has 2m high south facing windows. Great for passive solar gain in the winter. Less useful for the same in summer.

I'm thinking of putting up some of the adhesive window foil to reduce the amount of sun that comes in during the day. Does anyone have any experience with this stuff ?

I'm thinking the window foil that clings to the window rather than uses a glue. And claims to cut out 98% of the energy coming in.

Thanks

J

[The Family Cyclist]

I have window foils fitted to my office window, we had a window replaced in winter and foil was to be fitted a few weeks later. My chair was getting hot from the sun on the window so foils make a big difference

You can get paint for greenhouses (this isn't a joke) which cut heat transmission through the glass but would probably look like your a shut down business

[Adam]

Wouldn't the window film stop the heat build-up during winter though, meaning you'd need more heating?

Would just fitting blinds help, meaning simply lower them in the summer to keep the sun out and keep them up in the winter?

[Jurek]

One of my subbies main line of business is the fitting solar film to windows, they're based in Barcelona.
Usual practice is to fit it to the outside rather than the inside.
Make sure the glass is surgically clean before fitting - or expect air bubbles and blemishes to be evident.

[quixoticgeek]

Wouldn't the window film stop the heat build-up during winter though, meaning you'd need more heating?

Would just fitting blinds help, meaning simply lower them in the summer to keep the sun out and keep them up in the winter?

I was hoping it was removable so I could take it off at the end of September...

One of my subbies main line of business is the fitting solar film to windows, they're based in Barcelona.
Usual practice is to fit it to the outside rather than the inside.
Make sure the glass is surgically clean before fitting - or expect air bubbles and blemishes to be evident.

Wouldn't outside make it susceptible to being blown away by the wind ?

I'm expecting to have to give it a good cleaning first.

J

[Jurek]

Wouldn't the window film stop the heat build-up during winter though, meaning you'd need more heating?

Would just fitting blinds help, meaning simply lower them in the summer to keep the sun out and keep them up in the winter?

I was hoping it was removable so I could take it off at the end of September...

One of my subbies main line of business is the fitting solar film to windows, they're based in Barcelona.
Usual practice is to fit it to the outside rather than the inside.
Make sure the glass is surgically clean before fitting - or expect air bubbles and blemishes to be evident.

Wouldn't outside make it susceptible to being blown away by the wind ?

I'm expecting to have to give it a good cleaning first.

J

Yes.
It is an absolute pig to fit.

ETA - It is removable in so much as the longer it is on there, the more difficult it will be to remove.

[Asterix, the former Gaul.]

In France I paid quite a bit extra for a velux window with glass that blocked the heat of the sun.  It looks quite like ordinary glass but is very effective.  I could test it by standing under it open and closed. If you opened it on a hot day you soon shut it again.  In the UK I use blinds on the veluxes and find that very effective, too.

[quixoticgeek]

I can't install blinds, for various reasons, but mostly due to the fact I don't own the flat. Hence the idea of something that I can easily remove.

J

[chrisbainbridge]

Could you cut a piece of tinted polycarbonate to just fit n the window?

[quixoticgeek]

Could you cut a piece of tinted polycarbonate to just fit n the window?

Yes. But I'm not sure what it would achieve. It would act as a black body, so would convert the energy it stops coming through into heat that would radiate inside. The foil is reflective, so it sends the heat back out. Not in.

I have considered just using a space blanket taped over the window...

J

[liam_whippet]

Pretty sure we had discussion of this a few years back - didn't we have a heatwave before we had a pandemic? - and the collective wisdom was that the best solution was to put something on the outside of the window, if possible. [Stops the glass heating up.]

Foil was recommended - and plan B was to fit it inside the window.

Lots of good advice in the original thread, if you can find it?

[For what it's worth, I improvised shutters by hanging a duvet cover across/over each of the south-facing windows [on the outside] which kept the direct sun off the glass.]

HTH

[Polar Bear]

I'm considering a pile of cheap foil blankets and some framing made of batten which I can hang over the window casement on the outside when needed.  Would keep the heat out when most needed.

[quixoticgeek]

I'm considering a pile of cheap foil blankets and some framing made of batten which I can hang over the window casement on the outside when needed.  Would keep the heat out when most needed.

I'm seven floors up in a country notorious for it's wind...

J

[Kim]

During the last heatwave, I molished a couple of window-shaped panels of correx, covered with a layer of bubblewrap and a layer of foil (largely on the basis that these were the materials I had to hand), for ease of gaffer-taping over the west-facing upstairs window.

I'm not sure how effective it is at reflecting heat, on account of being the wrong side of some fairly efficient double-glazing, but it does an excellent job of blocking the sunlight^[1] without impeding airflow the way the curtains do.


_{[1] Barakta is a troglodyte.}

[Polar Bear]

I too have been a fused of being a troglodyte and I don't mind one bit.

I have thermal window blinds between the glass and the curtains in the bedroom and in some rooms just the blind.  They are excellent in winter but what happens is that they trap the heat between the glass and the blind.

QG:  the UK is notoriously windy too.  I expect to have to molish something of significant sturdiness.  My ideal in fact would simply be made to measure "fitted sheet" style covers for the casements but there are fixed panes too which would require something different. 

Whatever I do if anything is clearly not going to be permanent.  Louvre style shutters would be lovely but ongoing maintenance becomes a thing and due to the design of the property only two windows could benefit from shutters.

[DuncanM]

I have made myself a sun shield that I velcro to the outside of my window using this stuff:
https://www.toolstation.com/ybs-general-purpose-thermawrap-insulation/p16779?utm_source=googleshopping&utm_medium=feed&utm_campaign=googleshoppingfeed&mkwid=_dc&pcrid=&pkw=&pmt=&gclid=Cj0KCQjw7aqkBhDPARIsAKGa0oL7-jrr4Ry89tOteQ4_1UF5LgDC4c1Wau3R_zATDhteIFHQ6cSxxakaAqeHEALw_wcB&gclsrc=aw.ds
If you can't open the window then attaching stuff to the outside is going to be awkward, I don't know if this would work if you put it on the inside, but it has to be better than aluminium foil.
My previous office installed the window tint stuff - it improved things in summer but it made the room much darker in winter, meaning we had the lights on more.

[Mrs Pingu]

All our lounge and bedroom windows go all the way up to the ceiling. There is no area of wall or plaster between the window frame and the ceiling. It's a really stupid design meaning you can't put up blinds or curtains without the light getting over the top.

[chrisbainbridge]

All our lounge and bedroom windows go all the way up to the ceiling. There is no area of wall or plaster between the window frame and the ceiling. It's a really stupid design meaning you can't put up blinds or curtains without the light getting over the top.

Our blind fitter inserted a small frame, approx imately 1cm square around the frame and then the blinds were motor driven from bottom to top.  This was for an and window of a vaulted ceiling.  One of the things i really enjoyed at night was watching the blinds go up. 

[jiberjaber]

Amazon have solar reflecting film, give the window a good clean, spray on a mixture of soapy water and apply, squeedge it and trim to suit using a sharp blade.   
Same as you would do if adding privacy film.

Pull it off at winter time! (or leave it on)

You can probably source it cheaper elsewhere but for an experiment...