Which is cooler windows open or closed.

[LancashireButterPie]

I'm lying here in a lovely cool room with the curtains closed and the windows open, there is a nice cooling airflow. DH is insisting on closing the window to keep the room cool because he's seen that advice on the TV.

How does closing the window cool the room?
Surely for hundreds of years if your greenhouse was overheating you would open the windows?

The other rooms in our house which have closed windows (it's 6am) are already hot.

Windows open or closed? Please settle the argument.

Open for the next hour and then closed. The air warms up

Open now while it’s still cool outside then close when it warms up

Closed when the outside temperature exceeds the inside temp then open again when it doesn’t. It does work but it’s horrible and made more bearable by aircon. We had to do it when we lived in Cyprus so know it makes a difference. Let the cool air in while you can though.

Open for now while it’s colder outside than in; closed later in the morning and through the day once it heats up outside and it’s hotter outside than in; open again in the evening when it’s cooled outside.

Yeah open while it’s cooler outside than inside and then close them by about 8am - well that’s what we do anyway. Last night my bedroom dropped down to 25°, think it’s the coolest it’s been in a while, I got under the duvet 😂

On the radio they were saying curtains closed windows closed during the day then windows opened in the evening and it seems to be working here (I close the windows and curtains just before bed). It might depend on room orientation though, I don’t know

While it’s cooler outside than inside you should have the windows open. Then before it starts getting too hot outside you close them to stop the hot air coming in. So enjoy the cool breeze while you can!

Open the windows as soon as the air cools at night and close windows and curtains when it warms up or when the strong sun is directly on them.

I open mine on the cool side of the house, closed on the sunny side then at around midday I switch them all round. I have managed to keep downstairs at least quite cool during the day. Once dh and the kids come home from school and leave windows open the place heats up very quickly.

My bedroom is south facing so at the moment we have the windows open. You’re saying it feels cool so clearly it’s cooler outside currently. When the sun comes round and hits this room then we close the curtains and windows. There is a time when all the windows and blinds are closed and then when the sun has gone down a bit we open the windows at the front ( which is north facing ). At night we have all the windows open front and back and the bedroom doors open to allow some cross breeze.

At 6am, I'd still have the windows open. I close them about 9-10am.

You have windows open during the night, to let the cool air in.

As soon as it starts getting hot outside or you get sun on the windows, you close the windows to keep the cool night air inside.

We keep windows closed during the day unless there is actual air movement and curtains / shutters shut on whatever side of the house the sun is on. if out all day sll shutters are closed.

in the daytime, the front of our house gets blasted with sun so those windows shut and curtains drawn. Back windows open with curtains shut. Come 2pm it switches so we open front and close back.

Windows and doors open when cooler outside. Upstairs room windows and doors open all night. First thing (usually about 5am!) I open all downstairs doors and windows. Leave them open until the air outside becomes hotter than in. Then I close all windows and curtains all day. I reopen them once air cools enough (about 9.30pm yesterday)
I also open the loft hatch when its cooler outside as warm travels upwards and can escape the insulation through the roof. That works really well.

When the air outside is cooler than the air inside, open the windows (and preferably curtains too) and the air inside will cool down.

When the air outside is hotter than the air inside, keep the windows closed (and curtains closed to stop the sun shining in).

Open now while the air is cooler outside than in. During this time try and create airflow through your home, I'm using a fan to get the cool air to go upstairs and I have opened the back and front doors so there's a good draught.
Then close on the sunny side as soon as the air there gets warmer and pull the blinds curtains and put up cardboard at the window as extra insulation if you're a bit of nut like me! Later on close the other windows as the air temperature warmer on your shady side, and think of snowy days!

It's 21c outside. I have the windows and doors wide open because it's currently 25c inside.

The moment it's 25c outside I'll close it all up again because it's going to be 30c+ here today and I don't want the house to be as hot indoors as outdoors.

Yesterday at lunch time it was 12c cooler indoors than out. With no aircon.

That's why.

Have you got thermometers inside and out? Breezes can be deceptive - the cooling effect of air moving in your skin can fool you into thinking it’s cooler than it is.

Here it’s been 26 overnight 🙄. This is as cool as it’s going to get. So from 6am our windows are wide open and fans are moving air around. Usually it blows through but it’s so very still atm.

if it’s a sunny day, we shut everything on the south facing side as soon as the sun comes round - usually 9:40/10:00am. Shutters, windows, everything. Open the shutters around 5pm when the sun has moved over, but it’s still 40+ degrees out, so the windows stay shut.

on the shady side, we keep the windows open until the thermometer tells us that it’s hotter outside than inside. Then we shut the windows but leave the shutters open as there’s no direct sunlight on that side.

but we’re in France and have been in a heatwave for weeks now 😭. Everything in our apartment is around 28-29 degrees, the heat has seeped into everything. So it’s really hard to cool it down at all. Even towels in cupboards, clothes from drawers feel hot.

I find if I have the curtains and window shut our living room becomes unbearably hot and has a heavy hot air but no air flow. We are better not shutting the curtains as although it is hot, there is air!

It's very simple, surely - if it's hotter outside than in and windows are open, you're letting heat in. If it's cooler outside than in, you're letting heat out.

I've had all the windows wide open overnight, and managed to get the temp down from 29 to 23. Now I'm here with all windows closed (tinfoil on the outside of the south-facing one) and all curtains closed. It'll stay that way until it's getting dark. Don't own a fan, but obviously that would be the way to get the breeze if you want it.

You keep them closed in the day when it’s hot outside and open them in the evening/ overnight to let in cool air. Then you keep the cool air inside when the outside temperature is hotter than inside, which has night-temperature air inside. It’s just basic physics. I’m always baffled seeing people with windows open on hot days then complaining their house is hot inside. What did they think would happen?!

The moment it goes over 20deg outside, everything gets closed. And blinds shut.

By 3pm when it's 33deg outside, it's only 23 inside our house. Blissful.

Upstairs goes up to 27 during the day but drops to 23 at night. If we left the windows open it would just blow hot air in. How is that pleasant?

I did an experiment in my sunny living room over the last two days and it was only marginally better to have curtains closed/windows open. I think a brick house facing into the hot sun will heat up anyway.

Open 24 hours a day.

There’s a cool breeze from the east today. We haven’t had that so far this heatwave. So take advantage of that with windows open for a bit then close curtains for the afternoon and reopen them as the sun moves around the rooms in your house.