As I write this, the UK is in its third heatwave of 2026.
I’ve previously taken several steps to prevent my house from overheating:
I installed External Wall Insulation (EWI) – mostly for winter heat retention, but in theory it may also help exclude heat in the summer.
I fitted solar heat reduction window film on some of the windows with the worst solar gain. Many internal films will damage double glazing, but I found these two films that are supposedly safe to use:
- This Neutral Solar Control Heat Reduction Low Colour Tint Window Film reduces heat by 59% and lets 70% of visible light through (i.e. blocks 30%). I used this in occupied rooms where I still wanted a good view out.
- This True One Way Mirror Vision, Silver Reflective Window Film. Solar Heat Reduction Tint blocks 80%+ of heat but also only lets through 10% of visible light (blocks 90%). It’s mirror privacy glass but it’s very dark in that room now. I only used it for a spare bedroom not regularly occupied.
Both helped in the previous heat waves. I have no relationship with this company, but they were the only one I found that published the specs of their films, so I bought from them.
After the first heat wave I also bought a portable air conditioner. I bought one of the very rare (in the UK) two hose models which are much more efficient. It was very expensive. But there’s a whole subculture in modding single hose models to make them two hose models. That’s the budget option.
My 6000 BTU aircon can keep my bedroom to 23ºC in the day, and 21ºC at night, so that’s my haven. But the rest of the house rapidly gets to 25 – 27ºC, and even hotter in multi-day heatwaves.
In the second heatwave I put reflective foil survival blankets on the outsides of two of the windows that didn’t have window film on them, and that helped a lot:
But that was quite an effort to do, and not very reusable.
So as the third heatwave approached, I decided to make some DIY reflective window blinds that would attach to the outside of the windows using suckers.
This is what I bought (links are Amazon UK affiliate links):
- EconoHome Radiator Reflector Foil – 3mm Foam Insulation Core £13.99. I got this product as it has a foam core rather than bubble-wrap core, which I thought might be a bit more rigid.
- 30 Pcs Car Windshield Suction Cups £4.49. I got these just because they were cheap, had a lot in the packet, and could be shipped quickly!
- Duck Tape Original Silver, 50mm x 50m £6.70 (if you don’t already have any gaffer tape – or like me you only had black and wanted a neater result).
This is how I made the blinds:
First I cut the foam/foil to the size of each window, leaving a little overlap around the edges.
For the downstairs windows I covered the whole frame. For the upstairs window I made separate blinds for each opening, since I would need to lean out the window to put each on individually.
I then decided where to put the suckers, and I put a square of gaffer tape at those points. The idea is to have gaffer tape reinforcing the foil, so the suckers pull on the tape which is quite strong, not on the fragile foam/foil.
I then poked a hole in the middle of each square of gaffer tape, turned the blind over, and covered the visible holes with matching gaffer tape squares. Finally I turned it back to the original side and poked through the holes again to pierce the tape on the second side.
To install the flexible suckers, I poked needle-nose pliers through from one side:
And grabbed the handle/hook of the sucker with the pliers, and pulled it through. They deform extensively so it’s possible to pull it through without the hole getting significantly bigger:
To stick the blinds up, you will probably need to clean the window first, otherwise the suckers won’t stick to the dirty glass. Also wiping the suckers with a wet cloth before you stick them can make them stick more easily.
For the upstairs window, my windows have a catch to allow the hinges to slide so you can clean the outside. Using those allowed me to put the blind on the window I was opening.
Here are the final blinds, stuck to the outside:
And this is what they look like from the inside:
