Strategies for staying cool

OK. Trouble is, since we don't have shutters as rule here, to me the word "shutter" always conjures up the contenental ones, not roller-type.

Yes.

Not in this country, where windows open outwards. On the continent, windows open inwards.

I live in a bungalow, but not in a war zone.

Anyway some windows can be locked slightly open to allow ventilation and others are high small windows that can be opened near the ceiling.

It is perfectly possible but you have to design it in.

Although I prefer windows open on the shady side of the house.

Mirror finish mylar bluetacked onto the inner surface of the window reflects 90% of the incident light back before it even hits the curtains. It is a relatively good insulator too so although it gets hot it isn't very effective at transferring heat into the air. For me it holds a SW facing home office down to working temperature until the late afternoon without too much difficulty even in this heat.

Windows open overnight as you describe to bring the temperature down.

The OP is doing something wrong and/or has unreasonable expectations.

Some eco new build buildings are overheating now because they have plenty of solar gain, are well insulated but a tiny thermal mass. My thick solid walls buffer the outside temperature pretty well.

You want the outer surface as white as you can get with the smallest volume of trapped air against the glass and if you can the inner surface with a metallic mirror finish. You can't stop the blind getting mad hot but you can prevent it from convecting and radiating heat into the room.

I doubt that a layer of foil inside the blinds themselves will make much if any difference at all. Radiation shielding only really makes much of a difference once the blind has reached 30C above ambient.

A layer of insulation helps but only if you are able to prevent the even hotter air trapped against the glass from escaping into the room. I suspect that is where the OP is coming unstuck.

Tim Streater snipped-for-privacy@greenbee.net wrote

No you don?t with well designed shutters.

We don't use flyscreens in the UK. I suppose we could put bars on the windows like they used to in nurseries.

Maybe your flat just has very poor thermal performance. Uninsulated cavities facing the sun will also get hot very quickly and conduct that heat through the inner leaf.

Don't rely on 'new builds' being built with the building-regs insulation because developers frequently don't bother, or just slap a band of full-full at the top of the cavity to keep the NHBC inspector happy.

Does it lose heat equally quickly when there is a stiff northerly breeze when the temp is near or below zero ?

this is a temporary solution for use 2 weeks of the year

it isn't going to be a rigid construction that matches the profile of the windows

that's an unrealistic expectation

we'll have to agree to disagree on on the point of:

it taking 4 hours to reach maximum temp instead of it taking 2 hours to reach (the same) maximum temp, as being better than nothing.

OTOH, If your argument is that it stops the room reaching the maximum temp at all, then you are wrong.

but I don't have the resources to do it properly

the task here is to find the best bodge within a set of constraints.

and so far, none of the suggested bodges has worked.

I'm doing what people suggested would work

and my reply that it does not is aimed at them.

if you mean that it heats up through the walls, then nope (as I would have a freezing house in winter, which I don't)

I have the opposite problem, my house is not cooling overnight through the walls, so I start each day near the previous day's maximum temp.

and solar energy through the windows (blocked off or not) does the rest

Oh yes it is

is it?

I think you are taking that too literally

None of the suggested and viable solutions have worked.

I'm sure that I could easily solve this problem if I knocked the block down and rebuilt it, but that not a practical solution.

For the umpteenth time

I have no access to the outside of my window.

and even if I did block management would complain and tell, me to remove it.

even people with access to the outside of their windows don't want to go around covering them in tin foil.

It looks ridiculous

we haven't really got a heat wave this week

that just British exaggeration.

we have the normal one week of summer that we usually get.

If we are really lucky a second week will coma along next month.

it's not the outer frame that's too small, it's the bit that contains the beading that clips in the glass. That is very narrow on my windows. And that's the bit that clips in these blinds

Oh so there's a range of different foil blankets at the camping store is there?

Didn't see any others.

As it's going to require tools that people don't routinely have I would regard it as non trivial

but even so, at 100 pounds a time, I personally not going to chance it

they attach to the window by clipping into/onto the frigging frame

you obviously don't know have a clue what you are talking about here.

I think you mean it conjures up the "medieval" type

this is the standard continental shutter from the latter 20th century

I've now got fly screens on my windows, To stop the pesky flies getting in (why would you call something with a different purpose a fly screen?)

It works perfectly for me here.

But of course my curtains are properly insulated triple layer lined and interlined and seal well to the wall at the top.

Some random scrap of unlined curtain is just going to get hot and transfer the heat into the room

Double glazing means you don't need insulated curtains - except in summer

So open the windows.

Then stop it

In the US they seem to use fly screens on the front door as an extra barrier to visitors. They can open the main door and talk to a visitor through the screen. Sometimes the extra door isn't a fly screen but some sort of wrought iron work, or even glass. I suppose with aircon you don't need fly screens. I don't know what the etiquette is about the visitor opening the screen door and knocking on the main door: maybe only friends are supposed to do this.

Of course I leave the f****ng windows open

Jeeze!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

at night? you have ignored all other advice so its arguable that you have done so

Flats are crap anyway - you wont be well insulated from your neighbours

Ok, how much electricity do you use during the day ?. I've been to 'modern' flats where the downlighters use a daft amount of power and the design of the building forces the occupants to need them on even during the day.

Do you still have an old-fashioned plasma telly ?. I know it's unlikely but some footy fans have kept theirs. How much cooking to you do ?.

If you are above the ground floor, can you not open the windows at night to allow some ventilation ?. Unless you live in central London which has its own hot humid microclimate this should help, it does for me.

I once worked with a chap who lived in a 1960's flat with electric heating elements that were built into the ceiling. He never needed any heating because of the heat coming up from the downstairs flat !.