this post was submitted on 27 Jun 2025
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Hi there, time to share ways to keep your home cool during hot times

So ok, usual ways I use:

  • open everything during night
  • close everything during day
  • external sheets on windows without shutters
  • some curtains to prevent heat from going upstairs

I was also wondering if plants could also help inside, any ideas ?

Share your advices !

top 38 comments
sorted by: hot top controversial new old
[–] JubilantJaguar@lemmy.world 24 points 3 hours ago (2 children)

Lose weight. I'm totally serious. Thin people have much higher natural tolerance for heat.

It's no coincidence that so many developed countries have become addicted to AC. The fact is that most people there are now overweight and in many (USA most obviously) over 40% are literally obese. Conversely, AC is much less common in places like France and Japan, and it's not just because they're too cheap.

If you want to stay cool in a heatwave, it helps not to be wearing a blubber overcoat that you can't remove.

[–] starlinguk@lemmy.world 1 points 6 minutes ago* (last edited 5 minutes ago)

How is losing weight going to help right now? They can hardly lose enough weight in time for the next heatwave.

Or maybe they're in the menopause.

Or maybe it's 50C out.

Or maybe they're on one of the plethora of medications that causes heat intolerance.

Or maybe they're elderly.

AC is horrifically expensive (energy bills) and terrible for the environment, by the way. People aren't cheap, they can't afford it.

[–] th3dogcow@lemmy.world 12 points 2 hours ago (1 children)

Conversely, AC is much less common in places like France and Japan, and it's not just because they're too cheap.

I assure you that practically every household in Japan has an air conditioner these days. Maybe not some decades ago but things have changed, including the climate. And companies are legally required to keep offices at no higher than 28°C, too.

[–] JubilantJaguar@lemmy.world -1 points 2 hours ago (2 children)

Offices in all countries have AC, the question is about homes. I doubt "practically every household" in Hokkaido has AC. Here in northern Europe, very few do.

[–] starlinguk@lemmy.world 1 points 4 minutes ago

My office in Southern Germany doesn't have AC, even though it should. It's the hottest part of Germany.

[–] th3dogcow@lemmy.world 2 points 2 hours ago* (last edited 2 hours ago) (1 children)

Every home I have visited in Japan over the past two decades has had A/C units. You may be right that in regions where it is very cold an A/C unit may not be necessary. However, as heat pumps are one of if not the most energy efficient ways to not only cool but also heat a home, I wouldn't be surprised to find them even in colder regions.

Add on the fact that houses in Japan are generally considered a depreciating asset, so until recently demolitions and new construction were favored over renovations, I stand by my first statement.

Additionally, every place I have ever rented has come with at least one A/C unit, and additional holes are predrilled in other rooms so that split systems can be installed.

[–] JubilantJaguar@lemmy.world 2 points 2 hours ago (1 children)

Fair enough. Most of Japan is hotter in summer than northern Europe. Here it has been 35C for much of the last week and domestic AC penetration remains extremely low. There are also quite few fat people, and the two things are probably at least a little bit connected.

[–] th3dogcow@lemmy.world 3 points 1 hour ago

I don't disagree that people who are overweight will feel hotter. The rainy season makes it feel hotter than just the temperature here, too. Buildings here are probably more poorly insulated, too.

[–] LogicalDrivel@sopuli.xyz 2 points 2 hours ago

I put foil insulation on some of my bigger windows in the summer. Especially southern facing windows (in northern hemisphere). That mixed with tons of fans and the occasional cold towel when needed helps tremendously.

[–] bluGill@fedia.io 10 points 3 hours ago (1 children)

Look at old hot climates.

notice the afternoon siesta. Sleep in the shade in the hot of the day and work (play) later into the night.

notice large covered porches around the house. Spend more time outside in the breeze and shade.

notice the large windows and doors. When you are inside get plenty of ventilation-

notice the ceiling fan (often slave pulled). Be glad we now have electric fans.

notice the folding hand fans. Portable fans exist, though most of the time the hand fan is better - get one.

[–] starlinguk@lemmy.world 1 points 3 minutes ago* (last edited 2 minutes ago)

People in hot climates do not sit outside. They also do not open their windows. Because they're not insane.

[–] d00phy@lemmy.world 8 points 4 hours ago (2 children)

Something I haven’t seen mentioned is an attic fan. They’re mounted on the ceiling of your highest floor. These used to be common before AC became so widespread. Basically, you open your windows, and the fan sucks air in through the windows, through the house and up into the attic, where an exhaust fan can push it out.

[–] jubilationtcornpone@sh.itjust.works 2 points 2 hours ago (1 children)

Second this but wanted to add that a remotely mounted fan (one that's connected to the intake vent through a duct rather than being mounted directly in the ceiling) significantly improves the experience because it cuts down on the noise and minimizes heat losses in winter.

We have a gable mounted attic fan that draws air through the house. 5000 cfm makes for a nice breeze.

[–] trailee@sh.itjust.works 2 points 1 hour ago

Gable-mounted still incurs direct vibration into the structure. I have a QuietCool whole house fan that is suspended in midair from the gables, to reduce that vibration and noise, while being ducted from a framed opening in the hallway ceiling.

Whole house fans are pretty great during the right season, but you need to be aware of the humidity level outside or you can make things worse even if seems cooler at the moment. I also have central AC that gets run either when it’s too humid or too hot at night. But overall I’m very happy with the whole house fan and only having moderate insulation - the house resists heat incursion during the day and then we can quickly cool things down in the evening without using too much electricity.

[–] bluGill@fedia.io 5 points 3 hours ago

They were mostly had such poor insulation as to be not worth having because of the losses in winter. There is a good reason most people hove tore them out when they get ac.

[–] Quilotoa@lemmy.ca 2 points 2 hours ago

As a northern Canadian, I kinda chuckle at the need for an air conditioner. Of course, my punishment in winter.

[–] RedditIsDeddit@lemmy.world 6 points 4 hours ago

Fans! push and pull air according to wind direction

[–] trd@feddit.nu 7 points 4 hours ago

Drink alot of water, then try to pee in the air and catch it with your mouth, all the sudden the heat is the least of your problems.

[–] cloudless@piefed.social 48 points 7 hours ago (2 children)
[–] GaMEChld@lemmy.world 10 points 6 hours ago

ᕕ( ᐛ )ᕗ

[–] Boxscape 5 points 6 hours ago
[–] susi7802@sopuli.xyz 44 points 7 hours ago

Most importantly: Make sure no direct sunlight enters the house. Insulate your roof. Plants in the house can have a modest cooling effect. Close doors to rooms that get hot faster. Lower floors (especially cellars) are cooler, with a small ventilator this cooler air can be transported upwards. At night, use small ventilators to “pump” cool night air through all the floors.

[–] napkin2020@sh.itjust.works 12 points 6 hours ago

Related

Apparently window awnings make a considerable difference.

[–] Goldholz@lemmy.blahaj.zone 4 points 4 hours ago (1 children)
[–] starlinguk@lemmy.world 1 points 1 minute ago

At night. Not when it's 40C out.

[–] GaMEChld@lemmy.world 18 points 6 hours ago (1 children)

If you live in a humid area, AC will become more and more valuable. Wet bulb temperature. At some point your sweat will no longer evaporate and you'll die. Climate change cometh.

[–] Elaine@lemm.ee 3 points 2 hours ago

Thanks, I went down a rabbit hole reading about wet bulb temperature.

[–] psx_crab@lemmy.zip 16 points 7 hours ago (1 children)

As someone from the equator with hot and humid air, this thing is common, it allow hot air in the attic to escape so the hot attic won't radiate into your house, while sucking fresh air into your house. Plant surrounding your home exterior also will help with the cooling as well, especially when it stop light from hitting your wall. I usually just open everything during day, but open everything during night will also help circulate the hot air heated by the heat-trapping concrete wall. As of now i can't open during night because my cat will escape, so i just use ac for half hour or so.

[–] JayGray91@piefed.social 8 points 6 hours ago (1 children)

as someone from a similar place, mosquitoes make opening windows at night a health hazard, unless you install netting.

I should be getting to do that...

[–] psx_crab@lemmy.zip 4 points 3 hours ago

Yeah the mozzy mesh is a life saver, for both mosquitoes and flying termite/ant swarm after rain, but do keep in mind that meshes will restrict some air flow. Still, it's better than nothing, and combine with that rooftop onion you might get better result.

[–] karpintero@lemmy.world 9 points 7 hours ago* (last edited 7 hours ago)

Air flow was key. Tried to get a good cross breeze from one end of the house to the other (unless the breeze is also hot). At night, we'd use a box fan in the window or door to get all the hot air out. If you can block your exterior walls/windows from getting direct sunlight, that should help. Curtains work (or you could also just place objects or plants in front to block the sunlight). Alternatively, you could install one of those large roll up sun shades for a more permanent solution. Did that for a few windows that get a lot of sun and made a big difference.

From personal experience, the following made a difference (but some will have a lot higher cost):

  1. Replacing the insulation in the roof/attic. You could also add radiant barriers, but insulation is probably a better bang for your buck.
  2. Insulating the exterior walls (drill and fill). Our walls used to be hot to the touch in the summer before this.
  3. Double pane windows
  4. Seal any air gaps or holes. Expanding foam is pretty good at this.

From what others have told me:

  1. Installing a whole house attic fan to evacuate hot air at the end of the day. My neighbor did this and swears by it.
  2. Painting your house a lighter color. Can't say how effective but makes sense intuitively.

Stuff that only sort of worked:

  1. Swamp coolers. Works ok in a pinch, but your house will feel humid like the tropics. Would personally skip.
  2. Portable AC. The exhaust hose gets hot so it's not as efficient as an external AC or window unit. But it could help if you're directly in front of the cold air vent.
[–] schmorpel@slrpnk.net 11 points 7 hours ago

Wet curtains, and if that's not enough a wet towel on the head (not your home, I know, but something to remember when your brain threatens to overheat and you've got no energy left to pursue another solution.

[–] untorquer@lemmy.world 7 points 7 hours ago

Using a reflective surface such as aluminum foil on the windows (shiny facing outside) will help. I've used contact spray adhesive on cardboard cut to size of window before. You can also get the bubble-wrap aluminum insulation.

Cut temps in my old studio from food-safe poultry temp to near ambient on the 100+F/40+C days.

[–] Hoohoo@fedia.io 5 points 6 hours ago

Blackout curtains on the sunny side reduce a lot of daytime heat.

[–] nivenkos@lemmy.world 2 points 5 hours ago

Just get AC, it works so well for de-humidifying too.

But otherwise blackout curtains can help a bit but also radiate heat themselves.

[–] acryline@framapiaf.org 6 points 7 hours ago

@salcie
On m'a parlé des films solaires adhésifs anti chaleur pour les vitres. Mais, je ne pourrais pas conseiller de marque.

[–] fistac0rpse@fedia.io 3 points 6 hours ago

move to Alaska?

[–] BurgerBaron@piefed.ca 3 points 7 hours ago

Didn't say if you own the home or not, but if so:

Mind it's only hot for 2-4 months out of the year for me, so I have a winterized attic fan. Just means I'm not losing heat in the winter and paid a little more to buy it. You can just get a regular attic fan if it's never or rarely cold where you live.

You leave windows open, but now there's negative pressure from pushing air out the attic where a lot of the heat is trapped and sucking in air from outside even if there's no breeze. I leave the attic access hole open when it's running. The rare day I still use a Window A/C to sleep.