A scientific question re opening/closing windows in the heat

[RudolphTheReindeer]

So we all know we should keep them shut when it's hotter outside than in, but which outside temp do we use?

in the shade its currently 27.2, in the sun its 37.1

as my bedroom is south facing and has the sun on it all day and it's 29.5 in there, do I go by the shady temp and open the window now, or the sun temp and keep it shut until later?

I open the windows on the shady side of the house and close those on the sunny side. Half way through the day I have to swap this arrangement around. I have no idea if that’s the best thing to do.

I do the highly scientific wave of a hand out the window and if it feels hotter out there than in, I close the window and curtains. Hope the heatwave passes soon. Ours ended today and it's blissfully cool at 16C this morning.

A lot also depends on if there’s a breeze. It’s breezy here now so everything is open even if it’s hotter outside as the breeze feels nicer.

You should go by the shade temperature, so windows open. However, the temperature gradient is very small, so you really would want to get some airflow going in order to get the outside air in.

Keep your curtains shut.

I do find once the sun has passed its safer to open the window, mainly as I'm likely to mistime and forget if I leave it. Though TBF currently in bedroom with blackout blind down and large fan on trying to escape for an hour.

I read somewhere about having a fan pointing towards the window so it pushes hot air back out, I've tried this but it only has a small amount of effectiveness before the room is overwhelmed.

Unless there's absolutely no breeze, we leave the windows open as I'd rather be a bit warmer with a breeze on me, than a bit cooler but in a stuffy house.

I open the windows and doors first thing in the morning, while it's still cooler outside than inside. Then close them all when the outside temperature cranks up (today, it was 09:30) and close all the blinds and curtains.

About an hour after sunset, I open every door and window and keep them open until I go to bed (which in this weather is at about 01:00).

Edited to add, the above enables me to keep the inside of the house at least 5 degrees cooler than the air outside. Currently, in the deep shade outside it's 33.4°c. Inside it's 29° upstairs and 27° downstairs. I've no idea what the temperature is in full sun. I didn't want to break the thermometer!

I opened mine to early yesterday and let loads of hot air in .
I'm going to wait till much later tonight to ooen if

Yes we open about 5 am

Regardless of what they say it's defo cooler here when I get a breeze flowing through the place.

Windows open people - keeping the windows shut is making a huge difference for us. It’s been 35 degrees shade temp here which means it reached the point where fans/breeze actually dehydrate you more. It’s currently 26 in my south facing living room (windows closed in daytime and covered on the outside) and 30 upstairs. I open windows about 9/10pm and close at 7am and it’s been getting down to 24 upstairs by morning.

Yes, me too. Having anything open is like having the oven door open.

😂 I actually did this too. It didnt feel cooler and there was no breeze so I have shut the front windows again for now

I used to feel the same but stuffy sometimes = 5-10 degrees cooler in the house in these temps so I take stuffy.

Wow that's hot. It's not too bad here today at around 27 but we're forecast 37 tomorrow.

Yes we do this too. I leave all the windows open overnight where possible and we close them again around 9/10 the next morning (depending on outside temp). My room went from 30.5 to 26 overnight last night.

This is exactly what I do. It’s not perfect but it’s the best of a bad bunch of options here.