Right way to keep your house cool

[Withyouinamo]

Which works better for you on a hot, sunny day?

a) trying to block sunlight by keeping curtains drawn - and doors & windows shut - so as to keep the air in the house cool, or

b) opening doors and windows to let any breeze blow through & let rising warm air escape from upstairs rooms.

Usually, windows and doors open early and late but closed once the sun hits them and curtains drawn.

Today is very breezy here, I've got all the doors and windows open and there is a lovely cool breeze through the house.

Only open the windows and doors when it's cooler outside than inside. In the really intense kind of heat that is coming our way, we keep our curtains closed more or less all day and open the windows late at night.

We are lucky enough to have a cellar, and we keep the cellar door open too.

Our house faces South, so we have full sun on the front of the house all day. I keep all curtains closed until the sun has gone past the front door and is in th SW, then open everything up as the air is cooler at the front then. We have a great breeze that goes through the house if I open the front and back door 😀 I live in Cyprus a so we don't even go out if the sun is high in the sky, it's siesta time!

It depends on the inside and outside temperatures, which way the rooms face, how well insulated the house is, which way the wind is blowing... Impossible to answer to without more details.

I open the windows as soon as my window ledge sleeping cat goes out around 3-4 am and they stay open all day until he resumes the position around 11pm. Disclaimer, we are in France, have insect netting on every window otherwise the window would not be opened.

Then when the sun hits that window in the afternoon, I keep the window open and close the curtains. Keeps it cool.

Back door, also with a magnetic insect curtain open all day to let it breeze through.

Our walls are 2 ft thick though so inside is always so much cooler even if the windows were never opened.

P.S. For me, I open the windows and doors in the morning to let cool air in and warm air out. Then I close the windows and curtains on the sunny side of the house once it gets warm outside.

As @LillyPJ said, too many variables.

As a default setting, I keep windows shut and some blinds and curtains shut. My house is lovely and cool today. But sometimes on a breezy day the through air from open windows can be really refreshing.

The physics of it is where there are two different temperatures (inside and out) they will try to become equal, so if it is hotter outside than in, keep windows closed, but if it is fresher outside than in, the get doors and windows open.

Blinds drawn and doors shut to stop hot air creeping into other rooms. We don’t open windows until 7pm ish. They’ll be open for about 30 minutes around 7am but usually the air is hotter outside than in.

my house is 100 years old so does a good job with keeping the heat out.

Windows (and blinds in the bedroom) shut during the day. Open them when the temperature starts to drop.

I do usually leave the back door open if I’m home so the dog can wander in and out. But that room doesn’t get hot because of the trees.

On a hot and humid day it's usually cooler air till about 9:00 10:00 at the latest in the morning.
That's when the windows close the blinds are pulled down and the curtains pulled across.
Seems like a waste of the beautiful sunlight it's darker than winter, but it works!
Light equals heat.

If, later in the evening a cool wind picks up of course the windows are thrown open but otherwise, not.
Here's a little tip that may sound crummy to some, but we have a large window that faces East, I discovered last year that an inexpensive car windscreen sun shade fit perfectly across the lower half of the window.
That keeps so much heat out as the sun reflects off the silvery plastic exterior. I just draw the curtains around it.
Years ago we had a front door that had a large decorative glass panel.
Again it faced East.
I remember I took cooking foil and completely covered the window from the inside not a chink of light came through and it really kept the heat from coming in through the window.
We have ceiling fans which work very well, without them little sleep would be had! The white noise they create is also useful.

Windows open all night then shut as soon as it gets hotter out than in. Yesterday that was 12.30, today it was 9.30.

What is best for you is completely dependent on the starting temperature of the house and how well insulated it is. If it’s poorly insulated and the indoor temperature will climb anyway, opening windows for the breeze is probably best.

If it’s well insulated and the temperature indoors only climbs slowly, shutting out the heat will work better.

I don't know how true this is, but apparently putting reflective stuff inside the window can cause the glass to crack in extreme cases. I always put reflective foil on the outside of my windows because of that.

Good point @Somanyquestionsss , that would be worth looking into.
I only can say that I used this method of keeping the heat from the sun from coming into the room for many summers, and nothing like that happened.
It could be because it faced east, and although the sun was very strong early in the morning the sun wasn't shining on it the entire day.

Our garden is North East. The back catches some of the sun in the morning so open all the windows briefly in the morning. Then shut all day as the sun goes to the front of the house. The sun is on the front from 2pm onwards. All front blinds and curtains then shut on that side. Throw everything open once inside thermostat matches met office temperature for outside. Bit windy today so might be able to get away with it a little earlier this evening.

This is what I keep trying to tell DH. We're in a 1930s 3 bed semi, we are currently sleeping in separate bedrooms due to his snoring so he has been sleeping in our bedroom which gets the early morning sun. He insists on keeping the windows closed at night "to keep insects and moths out" so the hot air is never released, because his argument for the morning is that the sun on the room so he needs to keep the windows and curtains shut.

I go in there in the morning and it's like a fetid teenage boy pit, the temperatuer difference is noticeable between in there and the rest of the house (I make sure the other windows are open and there is a through draft). The bedroom curtains are blackout thermal ones but they're not heavy enough to keep the heat out properly like very heavy expensive proper thick velvet curtains, for example. It just kinds of builds behind them inside the glass and then radiates out into the room, building and building.

It is causing arguments.

Best thing I have bought to help with cooling the house at the back is to buy two 'half parasols' - we butt them right up against the patio doors and kitchen window so the glass never gets hot as always shaded by the parasols, the result has been amazing!

All windows open overnight.
Shut to keep the cool air in in the day, but not if the flat is hotter than outside when windows are kept open. (It was 28 degrees this morning)
Hang sheets in windows and shut curtains as soon as the sun is on them
Open again as soon as sun is off the windows.

Currently 30degrees in SW facing flat.

Similar here. Best thing I spent (quite a lot of) money on was a big electric awning. I put it out early in the morning over the south-facing patio doors and the lounge stays cool. It makes a huge difference and it's lovely to sit out under too as the patio slabs don't get boiling hot either.

That's a great idea.

The best way to keep your house cool is to prevent heat getting in in the first place - hot countries use shutters on the outside of their windows. So putting up parasols outside your windows to prevent direct sunlight will surely help a lot.

Neither... Open 2 windows downstairs & 1 upstairs. Hang damp towels over the downstairs ones.

I open the windows whilst it's cooler out than in. Where we live it's cooler for the first part of the morning at least, then once the sun comes round all the windows are closed and curtains drawn on the west facing side (no south windows). I've taken to putting large pieces of thick cardboard up inside the window and that has helped along with black out curtains and normal curtains! Once the sun goes down, windows are opened. I have netting over the windows so no bugs get in.

This is where sash windows are better designed. You open them at the top and bottom, so hotter air rises out and cooler cycles in at the bottom.

I go with windows and doors all open first thing and then again when it starts to cool. Including the front door to get a good through flow. If I win the lottery I am moVing to a hotel with air conditioning for the next few months.

Oh wow I thought I might get 2 or 3 replies! There does seem to be a consensus re trying to keep cool air in the house if you can achieve it in the first place by having doors & windows open early & then shutting them & screening out the sun. But once, for whatever reason, the temperature inside equals outside, then you might as well open up & get the benefit of any breeze.

Interesting re siesta time @ayvasili I've often wondered why we don't try to follow that custom in hot summers, but I guess if you work & your British workplace isn't gonna adopt it too, you're stuck really.

And 2ft thick walls @Shedmistress must be lovely! I remember a holiday in a solid old French farmhouse in 40-degree heat, it was always cool indoors, not just the air temperature but underfoot on the stone floors. Shows the importance of insulation.

@AppleOfMyThirdEye my house is also 100 years old but I'm not sure whether it's better or worse insulated than a modern one. It's a pretty standard suburban terrace, and certainly we're told it is of the type that would never attain a C rating for an EPC (Energy Performance Certificate) because of inadequate insulation. Therefore unsuitable for an air-source heat pump etc. We've put in new windows & doors & it's not noticeably draughty in the winter, but none of this makes much difference, apparently.

Oh @Sunnydayze43 I envy you your ceiling fans! I would love that because they're quite quiet & my DP really dislikes the noise of a regular fan.

@CurlyhairedAssassin that sounds unbearable. Our bedroom is in a loft conversion and although it's a proper insulated job, no cowboys, nice Velux windows with blackout screens etc, it's just always 3-4 degrees hotter up there by the end of a summer day. How can anyone sleep in there without letting the day's hot air out?

I'm googling half-parasols, awnings and shutters, yeah we definitely need to adopt hot-country solutions. Cardboard's cheaper though @GentleSheep

We bit the bullet in 2022 & got an air conditioning unit to use on the hottest days, one of those tall portable jobs with a hose that pokes out of the window. It works, but not as well as a proper window or wall-mounted unit. It makes a worthwhile difference, you have to banish all thoughts of your lecky bill while it's on! It's about 50-90p per hour depending on how powerful your model is so if you have it on all evening from say 5pm to 10pm that's about £2.50 to £4.50 - a lot less than a takeaway. And every time someone goes in or out of the room everyone shouts "You're letting the cold out!"