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 !
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Pretty good (but long) answer with historic solutions here : https://solar.lowtechmagazine.com/2025/06/dressing-and-undressing-the-home/
My short answer : do not let the sunshine in (stores, awnings, shutters), let it flow let it go (air), I like big walls and I cannot lie
Probably not exactly the answer you’re looking for.
If you have access to sun and are tech savvy, hop on Facebook market place or equivalent. You can probably get very cheap used solar panels that still have plenty of output. Rig up a AC unit in one room and cool just it.
Surprised this hasn’t been mentioned yet, but awnings. Glass is a superb thermal conductor. Not even the best curtain in the world would prevent air getting hot through the window if the sun is hitting it directly. An awning is meant to shade the window glass, preventing heating way more than a curtain alone.
Also, if the home has several levels, open the upper floor windows more than the lower ones. Hot air expands and raises. If it has somewhere to escape it will keep the house cool and the windows will draw in wind. Wind moves faster at higher altitudes. That’s why attic fans are so effective.
Sleep outside, if you have a space. Get a deck umbrella, a mosquito net and a cot and a sleeping bag (actually on super hot days I used to just sleep on a towel). It’s so much cooler than trying to get by indoors with no AC, even with fans. And it’s rather pleasant.
Close on the sunny side during the day. If the air on the shadow side is cooler, less humid or same as inside, open that side. If your home is more humid or hot than the sunny side, close it just enough to prevent sun ray for entering.
If the heat is not also damp, put wet clothes next to windows or fan for natural refreshment. You can also spray water on your curtain.
Wear natural fiber, coton or lint. Loose clothes, that does cover you body. This way, the evaporation of sweat cools you down. You will also smell much less than if you are wearing synthetic fibers.
Wash your feet, your face, your forarm with water regularly. Do not use cold water, room-temperature or fresh is better but go all the way to the articulation (ankle, elbow), wash inside and outside and let the water dry on you.
Drink small amount of water regularly. Once again not cold.
Keet your heat cover when you expose yourself to the sun. When you get home change out of your clothes that were heated by the sun.
Do not over exercice.
I was also wondering if plants could also help inside, any ideas ?
They shouldn’t. Plants can raise humidity, but they have no power to break the the laws of thermodynamics. Once heat is in your house you can only really move it out of your house; there is no destroying it in place. Note this does not apply to plants just on the outside of your home, like on a roof.
Watch your use of appliances carefully. Even a fridge generates heat - it might be better to place it outdoors or semi-outdoors if you’re going to be really hardcore about your approach.
A better insulated house will keep heat out as well as cold, so all usual tips on building or renovating your envelope apply.
Years ago I was watching Doomsday Preppers and one fella dug a long trench, 100 foot if I’m not mistaken.
In the trench he laid a large PVC pipe and filled in the trench. At the far end of the pipe there was an air inlet. He ran the pipe into his basement and up inside a wall with an inline fan. Cool air, as well as fresh air.
Didn’t do anything for the humidity, I suspect.
He claimed it worked, I can not confirm.
It does make since as it’s about 4c/39f four feet/1.2m underground.
So DIY ground source heating/cooling, basically.
I suspect that’s not long and deep enough, but if it is, it will produce air at the local year-round average temperature, at all times. (Whatever that happens to be)
Thats basically how earthships are cooled. You can also run the pipe through an evaporative cooler to cool the air even more.
You can also run the pipe through an evaporative cooler to cool the air even more.
At some point there, you’ve just reinvented AC.
Only if you use a better working fluid and add compression and expansion steps, but a long pipe in a ditch filled with water isn’t what I would call AC quite yet.
Aren’t there AC systems that just evapourate water from municipal supplies to the atmosphere?
I mean, yes, I’d agree that blowing air over a standing water body isn’t AC, but we’re getting close.
I think on a purely technical note, Air Conditioning goes beyond just cooling the air and involves reduction of humidity. Personally, I wouldn’t consider it AC because you’d have to keep refilling the evaporator resivor, instead of just powering the device, but that is a nitpicky item that isn’t technically a requirement.
Sorry about the content in spanish, but some years ago there were news about someone placing agave or some succulents/cacti in people’s roofs, since some species “absorb” the heat, something along those lines.
Here https://youtu.be/BOjYB7qaESEAlso this plant seems to help refreshing the room in general
https://wikipedia.org/wiki/Dracaena_trifasciataI haven’t tested them yet since I am just growing my little garden on the roof of my house, but hope something of that helps.
Pretty much anything on a roof will cool you down. The soil which will contain water is slower to heat while the plants will be be absorbing solar energy and “perspiring” to cool you down.
Locations under large trees can be locally up to 10 degrees colder in the summer and 10 degrees warmer in the winter.
Curtains are a god send. Make sure you have them to isolate things coming into and out of your house. So have a curtain to isolate your entry way. That way the heat stays there. Same things at the stairs so you can keep the cool in the baseline while you stay there
Also to note that depending on your house and the outside temp its not worthwhile to open the windows at night. But generally it is better. Make sure you have a fan in the window blowing the hot air out as well. Its best if its upstairs to draw the cool air in.
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.
I gain weight this winter. I have such a trouble cooling down the part of my body that gain the weight. It is hard…
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.
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.
My office in Southern Germany doesn’t have AC, even though it should. It’s the hottest part of Germany.
Give it a couple of years and a few more heatwaves! This is the insidious problem with heatwaves, as I see it. Tolerance for heat and cold is in large part cultural - go to Portugal in winter to see how tolerant people can be of cold indoor temperatures. But with every new 3-day heatwave, Europeans are going to rush out to buy AC units to escape the immediate misery. Next thing we know the continent will be like the US, where it’s just unacceptable for indoor temperature to be outside the 19-23C range. And mass AC is just a climate disaster. That’s my worry.
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.
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.
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.
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.
I found it good advice. We don’t know every detail about OP life. Of course, some example won’t apply but that’s fine.
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.
People in hot climates do not sit outside. They also do not open their windows. Because they’re not insane.
In hot and dry climates, a breeze in a shady place works well, actually. In humid places it’s harder.
That actually has results counterintuitive to temperate people when it comes to clothing. Arabs don’t just cover up for modesty.
they do open windows. They also close them. When they do that depends on the situation.
livewise they sit outside at times. They also sit insides.
There are many different hot climates with different situations. You cannot make a blanket statement. And you cannot look at what they do today when ac is common to figrue it out (where at is common)
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.
My parents’ house has one, and every house needs this.
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.
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.
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.
Only fans.
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Only fans.
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.
