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.

As I type this I have

• North-facing upstairs windows and front door wide open
• [Completely exposed] South-facing back door wide open but covered with light-colour curtains.

There is a lovely breeze being pulled though the house. Weather says it is 29deg here right now, but I just turned the fan off as it is unnecessary.

The back of our house gets full sun in the morning while the front is in shade and is cooler. By the afternoon the sun has shifted to the front.

Hence my window opening / curtain closing is based on that. Curtains and windows at the back closed in the morning while windows at the front are open. Then by midday at the latest I close the windows at the front and the curtains in our bedroom, which is at the front.

Late in the evening, after 9pm, I open the front door wide and open all the bedroom windows to get cool airflow through. We actually had the front door open until 11pm last night. The bedrooms were very much more comfortable as a result.

Closing a window doesn't cool down a room, but if the air outside is hotter than the air inside, then you don't want to let hotter air in. It's like not opening the windows when you have the heating on in the winter.

You close the curtains as the sun shining in will warm the surfaces it hits and heat the room up.

Once it's cooler outside than it is inside as the sun goes down, opening the windows lets cooler air in.

What is warmer indoors when it’s colder outside in the winter? Open windows or closed?

If the external temperature is hotter than the temperature you want indoors then obviously keep the windows closed until the temperature is lower, from mid to low twenties outside.

I type so slowly that I cross posted with this more patient explanation lol

Same. Seems bizarre to need a duvet at 25 degrees though.

We open windows on shaded side then when sun moves around we shut them and open the other side up. Keep curtains closed and reopen once cooler at night

I feel the cold. Not that 25° indoors is cold but i was comfortable under the duvet, certainly not hot.
dh can’t sleep under the duvet when it gets above about 20, he runs very hot.

All of our windows are open with the blinds closed. Fans put in strategic places to move the air. It’s lovely and cool in my house.

It certainly doesn't make the difference I hoped it would. I'm wearing myself out trying to keep this red brick hellhole cool....Foil on the windows, shutting windows, blinds and curtains as soon as it starts getting warm outside after leaving everything open overnight.

It's still absolutely bloody baking upstairs by 3pm no matter what I do.

The house needs painting white that's for sure.

depends on the house but I would say open for mine as when I go outside it’s cooler than in my house

I dont think it makes much difference, my curtains are closed and window open but there's a nice breeze so its helping me cool down

If outside is cooler than inside and you have a nice cooling breeze then windows open. When it’s close to outside becomes warmer than inside, windows closed.

Open all the windows when it's cool (early morning and late evening) and then shut them once the outside starts to heat up. It's definitely cooler inside my house than outside, because from about 9am we've shut the hot air out by shutting the windows. At 6am you were definitely right, by 10am he was...

It's great all the posters are around to open and close windows when necessary.
I'm in a flat and work full time.
When I leave the sun is fully on one side and by the time I get back it's on the other, It's not got below 30 for a few days even overnight!

if the sun is beaming then all closed, if the sun disappears then try opening

What extra tasks require someone at home?

You open it all up early before work (I was up at 5am yesterday to do this and walk the dog) then close it up before you leave the house.

Open it all in the evening when it cools down then close what you need to for security at bedtime.

Rinse and repeat.

How can people find this so hard to understand?!

@LancashireButterPie what on earth are you going on about greenhouses for?! They are literally made of glass - unlike houses which have insulated roofs and walls!

If the air outside is cooler than the air inside, open the windows. If it's warmer outside, keep the windows closed. (Same principle as in winter when it's colder outside than in - you keep the heat in and the cold out.) If it feels stuffy with windows closed, use a fan.

It also helps massively to use blackout blinds and curtains. We keep the blinds and curtains closed on the sunny side of the house (and if we'll be out all day and unable to keep closing and opening, we just close everything before we go).

If the temperature cools down in the evening, overnight and in the early morning, you can easily keep your house at a reasonable temperature by following these common sense methods. The problem is when the outside temperature doesn't cool down enough overnight and you can't cool the house before the next boiling hot day.

electronic thermometers take the guess work out of this. Outside, back and front, and in a couple of rooms. As pps say, when it’s cooler outside than in open the windows. And vice versa. It’s not rocket science.

A breeze does not equal cool air. Even warmer air moving over your skin can feel cooling but all it’s doing is heating up the room, and you’ll feel it as soon as the air stops moving.

Depends if there is a breeze too, we get a through draft going which really helps

It doesn't though. See previous post. If it's a warm breeze it will heat up the room even if you feel cooler when the breeze hits you. Windows closed and fan on will actually keep you cooler.

The wind today was around 30c, so far higher than the internal temperature indoors! The breeze doesn't cool a thing when the temps are so high. It just dries you out more.

Curtains and windows closed during the day

Window open, fan going, lights off and curtains open at night

Unless you're on the ground floor, of course

As someone who has lived in Australia, close the windows and shut the curtains as pretty much everyone is saying. Open them in the evening once it's cooler outside than inside your house, and we leave them open all night but our bedrooms are not on the ground floor. Has been bearable for sleeping in our house this week.

I follow the sun

When I get in from. work in the mornings, the sun is reaching the front of the house, so I draw the blinds, pull the curtains that side of the house, and open the windows the other side

Late afternoon when the sun is in the rear, I close those windows, pull the curtains and open the front

I keep all internal doors open as well to let air flow

We haven't had the temps you guys down south have had, but high 20's when we are used to mid teens, its been hot for us as well