Keeping windows shut/curtains drawn builds up heat?

[PlinkPlonkFizz]

In preparation for the heatwave spike, I've been thinking about the advice to keep windows shut and blinds and curtains drawn.

AIBU to think this just creates a heat spot between your window and curtain and you'd be better off to open the top sash to allow that heat to escape?

I have the window open too especially at night

We have the vents in the windows open all year round. We also open windows and blinds in living room but have cats that don’t think they should have to actually push the flap in cat flap. but to be fair our house is old so and living room definitely not a heat trap.

We tilt the shutters on the west side to stop the heat getting in, and keep the blinds and windows closed on the top floor on the west side. East side windows all wide open. From years of thing the house is too hot, this is the system we've come to that works.

We have a big front window and shut the curtains on hot days but leave the top window open keeps the living room shaded and cool.

While the air is cooler outside than inside, we have the windows and curtains open on the shady side of the house, and closed where the sun hits the house. Then as the sun moves round we swap over. But when the air outside is hotter than inside, which today will be from about midday, we keep all the windows shut so the hot air isn’t let in.

I am currently sitting at my dining table on the shady side of the house with the patio doors open, bringing in a lovely cool breeze and cooling the room rapidly. Keeping downstairs cool means that hot air isn’t rising to the upstairs rooms and getting trapped under the roof insulation.

I understand the advice and I do think it's correct, but I also think it's still better to have the windows open.

My kitchen gets ridiculously hot in the daytime. It pretty much has constant sunlight from noon. It's got a large window and patio doors. If I shut the blinds and curtains over the doors, it IS cooler. BUT it is still hotter than if I was to open the patio doors.

I tend to shut the curtains but keep the windows open.

If there's a breeze outside, then having a window open and setting up a draft through the house helps.

If it's very still air, hotter outside than in, then better to keep it tightly shut.

In tropical countries they built houses with gaps under the eaves, so the air circulated and cooled. The old colonial houses were much pleasanter and more sought after than the modern concrete, glass and aircon houses.

Windows and blinds on the sunny side closed. Windows and blinds on the shady side open, if the outside is cooler than the inside.

All windows closed if the outside is hotter than the inside.

When we lived in a house where we had east and west facing windows I used to go home at lunch to do the switch on really hot days (for the dogs).

What you want is to set up a cross flow of air through your house from cool side to hot side and and updraft of cool air from downstairs to upstairs.

So windows closed is ok, but not really the best way…there’s a reason why many hot countries with no air con don’t even have glass windows ffs.

What we have is windows open and curtains open on north side of the house, and blinds most of way down and windows open on south side of the house. Air always moves from cool to hot..so this has set up a cross breeze of cool air coming in from the north side and flowing out the south side. As it’s a current of air, the hot air isn’t coming in from the south side. If we had south side windows closed, we would not have a cross breeze set up and the cool air on the north side wouldn’t be actively flowing in and across the house.

We also have east facing window in stairwell open as that creates an updraft where cool air is pulled I’m from downstairs north side and pushes hot air out the top of the stairs. This helps upstairs stay cool as the way the bedrooms are set up you can’t get a full cross breeze.

In Northern Ireland I have the heating on, no sign of a heat wave.

In our house it’s better to keep the windows and curtains closed as it’s hotter outside than in. As the sun moves round I start opening windows on the cooler side.
if you don’t want the gap between the curtains and windows to heat up blue tack card against the windows.

All windows / blinds and doors closed during the day, when the temp starts to drop even if only relative the the temp of the day, open the windows, keep them open overnight.

I forgot to open our bedroom curtains the other day and it was (apart from our blissfully cool downstairs lav) without doubt the coolest room in the house, so I've continued.

It depends on how hot it is. Late 20s/early 30s I’d keep windows open, especially if breezy, curtains shut in sunny spots. But when it’s 35+ as predicted for Monday the air will be hot and humid - having the windows open will let all that hot air in. So I would keep the windows open in the night/early morning and then shut them late morning.
Its a great time to wash your curtains. That helps to keep the house cool.

In Northern Ireland I have the heating on, no sign of a heat wave.

Helpful…

We have the windows open but curtains and blinds closed, with a small gap to allow air to come in and circulate. I'm in an Edwardian terrace so it naturally stays fairly cool (no carpets anywhere other than 3 bedrooms helps).

Though it's warm in our bedroom (loft conversion) and the stairs leading up to it. On the upside, I painted those stairs yesterday and they dried rapidly!

What you want is to set up a cross flow of air through your house from cool side to hot side and and updraft of cool air from downstairs to upstairs.

Unfortunately my South and West facing top floor flat has neither a cool side nor a downstairs. However I did realise yesterday that my curtains are far too thin and were doing nothing to keep the heat out, so this morning I hung blankets over the ones in the lounge and so far it seems cooler in there than it has for the past few days. Windows are closed.

Its a great time to wash your curtains. That helps to keep the house cool.

By which I obviously mean wash them and hang them up wet the night before or that morning - don’t take the curtains down on the day!

Yes, a detached house has more options compared to a flat. In your case you are right to keep windows closed. I feel really sorry for you and everyone in flats in this heat. Especially south facing like yours. Can’t be pleasant.

I have blackout curtains and the windows open. makes no difference its like an oven. room is south west facing so ive no chance.

The advice about keeping windows shut during the day only works if the room is not exposed to sun for much of the day. If it's a shaded room with not much direct sunlight, then yes keep the windows closed to stop the hot air getting in.

If however you have a South facing room or a loft room (like mine) which takes the full force of the sun all or most of the day, then your only hope is to open the windows (keep curtains / blinds shut for shade) and try to get a breeze. If you shut the windows the room just becomes an oven.

I'm in Switzerland, it was 34 yesterday.
I'm in an appartment with balcony - I had all the windows/doors open fully from early morning, then closed them and closed the shutters and curtains when it got warmer outside than in (around 11.30am). It was 26 when I went to bed around 11pm.
I think having shutters - metal, outside the windows - makes a big difference, far more effective than just curtains. Maybe something to consider in the future for buildings in the UK if summers continue to get hotter.
Theres a long thread over in the Weather Topic about the red warning. Lots of advice on how to handle it 🙂☀️

If it's warmer inside than out and the sun isn't shining in, then open curtains and windows

If it's the other way around don't

A breeze may make you feel / think colder but if it's hot and sunny you would be better keeping the room cooler and using water ( damp towel , spray) and a fan inside

I think Lockheart explains it well. I know the advice is to keep windows closed but ime it makes it much worse.

Not sure why the person from Northern Ireland has got heating on, it's not as hot as here but it's hardly cold.