There's so many different ways - ten I've counted - of trying to deal with overheating, as everyone will be wanting soon enough.

Blinds are an unsubtle barrier which prevents solar penetration but blocks the view out. Or some just partially block both. The ideal is something that blocks solar penetration while allowing unimpeded view - on southish windows an overhead pergola-like brise soleil can do this, blocking the summer high-elevation sun rays while leaving more horizontal view unimpeded. Unfortunately, for westish/eastish windows the offending sun rays are low elevation, so in blocking them you also block horizontal view out.

One low cost approach is internal reflective blinds, mounted tight behind the glass face i.e. within the frame opening. Incoming direct-solar radiation is at high frequency, which penetrates easily through glass. Once inside it falls on objects, which absorb the radiation, warm up and re-emit the radiation, but at low frequency, which is largely blocked by glass, especially if coated as is all modern double glazed units. So the heat is largely trapped within the room. However, if the incoming radiation can be immediately reflected by a tight-fitting reflective blind, rather than absorbed, it remains at high frequency and will mainly pass straight out again through the glass, apart from quite a lot of it which will bounce onto e.g. the window frame, and there be absorbed. Such reflective blinds can be fully opaque, or can be 2-5% transparent, so a dim view of outside is preserved. They are of course readily retractible, can be quite simple and cheap, and can be DIY-fitted. But frames, and any channels the blind runs in etc, can get extremely hot, radiating at low frequency into the room. The inner glass pane can also get very hot, possibly failing.

Stick-on glass films, available for both outside (expensive, professionally fitted) or internal (can be very cheap, DIY-fitted) do a similar job, but with the disadvantage that not 'retractible' - except the cheapest/crudest, yellow-tinged internal type, which is intended to be stripped off as soon as the hot season ends. The more effective at blocking summer rays, the more obstructive they are to winter view and daylight, and if internal, the more they can overheat the inner glass pane.

Firms are rubbing their hands at a sales boom that may rival the replacement windows trade - lots of people will pay a lot and be disappointed. Take competent advice, don't trust any salesman.

Posted By: djhAn internal blind is better than nothing, since it gets hot and warms the air

Significantly, even if it's properly reflective?

Posted By: fostertomStick-on glass films... ...if internal, the more they can overheat the inner glass pane.

A good point - many internal films come with warnings not to apply them to anything other than small double glazed units, due to the risk of the heating cracking the glass, though I'm not sure how often this actually happens.

Beware external aluminium louvre blinds unless you can guarantee that they will always be retracted when necessary - I see plenty in France that have been damaged in high winds. Steel blinds can also problematic since they quickly reach high temperatures and radiate the heat out again, especially those that trap hot air between then blind and the glass.

As you're probably aware, timber shutters, blinds and brise-soleils of various types have been used effectively for centuries in France, though they aren't cheap.

Apart from attaching things to the building, also consider what you can do in the garden (if any) by planting large shrubs or trees in strategic places, or growing vines or other deciduous plants up a pergola.

Bugger!

I come back after a hiatus and find this bombshell...

That's why they've not repsonded to my emails!


I fitted temporary louvres for this summer -much to the disgust of my neighbours as I just put a cobled structure of 4x2 and plywood to test sizes and angles.

It worked well, but fitting real louvres would require a large metal structure which would be expensive, ugly, and create problems with cold bridging and future EWI works.


Smartlouvre looked like the perfect solution.

I was also going to propose it to our local council to be fitted to bus windows to reduce the AC load and make passangers more comfortable.