What are your advices to cool homes without AC ?
Hi there, time to share ways to keep your home cool during hot times
So ok, usual ways I use:
I was also wondering if plants could also help inside, any ideas ?
Share your advices !
Only fans.
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Only fans.
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.
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.
This may explain why I'm wearing a hoodie in the office in late June while most everybody else is comfortable or still hot.
But, I also do lots of outdoors stuff and acclimate to heat up to a point.
AC is much less common in places like France
It's everywhere around me (in France) because it's becoming too hot, whether people are fat or not.
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.
I gain weight this winter. I have such a trouble cooling down the part of my body that gain the weight. It is hard...
Not disagreeing but none of my kids are at all fat and one is so hot-natured, it's not always just insulation. One of their cousins, too, she was just never cold and always hot.
I did always joke with my ex that I was built spare because I am from the hot part of the world, and he was padded because he was from Michigan.
Interesting anecdotes! There's actually a bit of truth in the last one, I believe. Bodily fat is more evenly distributed in Inuits and even Europeans than it is in, say, west Africans.
I mostly agree since it's healthy either way, but back when I was half my weight when I studied in a 4 seasons country, coming back to the year round hot and humid home country still makes me immediately sweat the moment I step out of the plane. Constantly felt like I always have a blanket on me. Anecdotal for sure, but I just want to say my piece.
Conversely, AC is much less common in places like France and Japan, and it's not just because they're too cheap.
This is completely wrong. Like 95% of all households in Japan have ACs. Even on the countryside. I was living in Japan for a year and the only time I visited a house without an AC was on an island with 1000 inhabitants.
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.
Thanks, I went down a rabbit hole reading about wet bulb temperature.
Yeah, this recent heat is expected to cause deaths. Not only because of the heat itself, but because of the humidity. Humans can tolerate extremely high +100°F temps when it’s dry… But when you start cranking up the humidity, that tolerable temperature quickly begins to drop. At 100% humidity, that tolerable temperature is only in the mid 80’s. Above that point, even the best fans won’t help cool you. Because fans only work by evaporating sweat, and in high humidity that sweat doesn’t evaporate.
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.
Huh? I sit outside, with a fan on, in up to 35/95F in the shade. And it's humid here. Outside hot does not feel as bad as inside hot, and you do learn to be still and cool enough. It is not weather to go running, but sitting, in the shade, with a fan? No problem.
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)
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.
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...
Apparently window awnings make a considerable difference.
I have a large room with clear story windows and the entire south wall is windows, in the desert. The roof extends out far enough to block the sun in the summer, but not in winter. In winter during the day it's 90F when it's below freezing outside. The amount of heat trapped from the sun coming in through windows is no joke.
I was searching to see if someone had posted this already because that was exactly what I wanted to contribute. Excellent work!
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
Came here to point to this.
Also, if outside noise is preventing one from keeping the windows open over night, get custom-fitted silicone earplugs.
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.
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.
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.
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.
Just keep in mind this only works if the humidity where you live is on the lower side. If you deal with high humidity where you live you won't experience nearly as much cooling from those wet curtains or the old wet towel over a box fan trick.
The towel on your head still works though because it's on a much smaller scale unless you're dealing with near 100% relative humidity. Double that with a fan of some type and you're in business.
When its hot, avoid cooking indoors if you can. Especially iff you dont have proper exhaust in your kitchen. Buy some food that require less heat or none. Sandwiches, Fruits, Salads, etc.
Keep your home cool and yourself too.
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):
From what others have told me:
Stuff that only sort of worked:
Painting your house a lighter color. Can’t say how effective but makes sense intuitively.
Probably makes a big difference. I just measured my patio, grass and driveway temps today with an infrared themometer. Grass was 109, patio was 123, and the blacktop was a whopping 148. My wife has been talking about using a cream or neutral gray finish on the driveway, and a 20 degree difference is definitely worth it.
Yep, it's a low-tech decision that'll pay dividends. Same reason I'd opt for a white or lighter colored car if it's going to be parked outside.
Should've also mentioned roofing shingles as well. See a lot of houses with dark roofs just soaking up sunlight.
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.
From a Deep South transplant who went through plenty of hurricanes with no electricity, a frozen gel pack between your thighs. You’re welcome
another on back of the neck, and for the ladies, small ones under the boobs
I wish I had enough boob to know about that last one lmao
If your roof is not shaded by trees, a light colored roof makes a huge difference. This can be accomplished a number of ways. Replacing your roofing material with a lighter color is ideal but expensive. Coating it with something like Henry Tropi-cool is durable but the product is also a little pricey. The absolute budget way to do this on an asphalt shingled roof is with a slurry of masonry lime. I've experimented with all of these methods and the results are dramatic. In my case the coating paid for itself within one season and made the house noticeably more comfortable.
Passive or Active Ventilation. The idea is to encourage air to pass through the home, which helps with removing heat from inside. Passive Ventilation would be opening windows, using wind catchers, etc. This depends on the design of your home, among other things that you probably don't really have control over. Active ventilation is the same idea, but you use strategically placed fans to induce good airflow. For example, if you have two windows that are opposite to each other, you can place a fan at one window to intake air, and a fan at the other window as exhaust.
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.
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)
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.
OP, do you have an air conditioned library or a cold springs near you? When I was living without AC I found that getting really cold at some point in the day chilled me off for quite a few hours, made the rest of the day feel better. I had a friend who would get in a cool shower then not dry off just lay in the wind from a fan.
@salcie
On m'a parlé des films solaires adhésifs anti chaleur pour les vitres. Mais, je ne pourrais pas conseiller de marque.
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.
My method is "live in Alaska."
If you can afford it, buy a single window AC unit, install it in your bedroom, and then live in there all summer. That's what my parents did when I was little and we lived in a house with no AC. If you can't afford that, a box fan in the window once the sun goes down, then shut it off in the early morning and close/black out the window/draw shades as soon as the sun is up to try and keep the cooler air in that one room for as long as possible.
Blackout curtains on the sunny side reduce a lot of daytime heat.
Open upstairs windows after 8-9 PM to let cool air in, blackout blinds work really well too
This works really well. I also open the downstairs windows. The hot air going up and out creates a draft effect, sucking in cold air from the downstairs windows.
I could never do this, I get swarmed by June bugs at about 850 everyday, it's like someone kicked a hornets nest outside my windows :(
Lüften (airing out)
At night. Not when it's 40C out.
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.
As a northern Canadian, I kinda chuckle at the need for an air conditioner. Of course, my punishment in winter.
They're becoming more common in the populated areas of Canada, although it's still a minority that has it where I live as well.
Climate change is really obvious at this point, and the smoke is awful...
Live somewhere it doesn't get hot.
There kind of.. isn't. I've been battling heat with extreme prejudice my entire life. MAYBE the closest thing to a solution is to drink lots of ice water and then hopefully you're not one of those people who can't sleep if its hot (i am).
Try to "store" as much "cold" as possible. i.e. if you have a half working a/c unit, run it at 100% at night and once the temperatures get as low as they're going to get, close all the windows, cover the windows, unplug fridge or whatever is producing heat you can afford to shut down and maybe if you're lucky it will be around 1 or 2 pm before it heats up to utter bullshit temperatures.
If you have a way to get unlimited free ice (IMPORTANT: and NOT from the fridge in the living space you are trying to cool), you can use that to cool things down in the evening when everything is the hottest. If you have to buy the ice, just buy a ac unit because it will pay for itself in no time. And if you're doing this because you can't afford the electricity, maybe see about wiring up a solar panel and battery which, again, will pay for itself if you could've afforded to literally buy bags of ice every day. And if you're doing this to protect the environment, get a ac unit that doesn't contain ozone-layer destroying coolant (i.e. most of them). Buying ice for cooling is incredibly inefficient.
You can also take the ice-based cooling strategy further. Get a bucket. A fan. A big radiator (you need quantity(sq area) not quality, get a shitty heater core one and not a pc watercooling one). A pc watercooling pump. Some tubing, along with whatever barb fittings and pipe clamps you need. Make it so that the radiator is sitting in front of a fan while having water from the bucket being pumped through it. Add your ice to the bucket. This system will dump the "cold" from the ice into the room as quickly as possible, MUCH quicker than just setting the ice in front of a fan to melt by itself. If you actually have a truly unlimited source of ice this will provide nearly the same amount of cooling (while the ice is fresh at least) as an actual window ac unit. I do this irl sometimes and usually keep one mostly set up and ready to go just in case my a/c stops working.
It's going to take time to find a cheap or free radiator if you're living like this for financial reasons but bending some copper tubing around the fan also works decently. If you buy it at the hardware store its likely going to come coiled up in a box and already in the perfect shape for this.
At a certain point, obtaining the amount of ice you need to maintain this becomes a problem. If you REALLY don't want to buy an ac unit at this point as maybe some kind of personal challenge or whatever, its time to science the shit out of it. Get a refrigerator. Put it outside, as leaving it inside will dump heat into the room defeating the purpose. Mod a bucket into the fridge and run 2 tubes out of it: an input and an output. Run this tubing into your living space somehow and into the radiator and the fan. You could alternatively put the fridge inside and find a way to attach a duct to the back of it to vent air outside which is may be more convenient depending on your living situation. Congratulations. You've built an a/c unit without technically actually building an a/c unit. Maybe in some countries this helps for tax purposes. I've never tried going this far with it before saying fuck it and getting an a/c unit so post pics if you do.
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.
move to Alaska?
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.
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.
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.
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.
Get a box fan and a coil of copper pipe, run the coil all around the front of the box fan like a snake going back and forth, on the top end of the pipe attach a box for icewater, and a bucket to catch the outflow.
Put an adjustable valve at the end going into the drain bucket and let it dribble a bit. You'll have to adjust it to get the longest cold air time/least having to get up to empty the valve
It's not super efficient but it's cheap and can be made with parts in the garage
You'll need a lot of ice tho
I've been getting by just fine with a couple standing fans. I've had to turn the ACS on a couple times for my kids when I was around 110F
Before going full blast AC in all the rooms I'll turn on the big Window unit in the living room and set up fans so it blows the cold air through the whole house (our house isn't big) and I find its a good middle ground. It cools down the rooms pretty well.
If you own the place or can get permission, a mini-split air conditioner is very easy to install with minimal tools, and they're pretty affordable online.
For under 500 buck including drill and bits you could have AC in a few days. It's not free, but it's a huge quality of life improvement.
Hot showers at night or when you’re feeling extremely overheated. Trust me, that’s way better than cold showers. First shower warm, then get soapy, and then shower as hot as you feel comfortable. I do this for over 10 years now and it’s amazing. My theory is that it heats up the body and due to the outside being cooler, it actually cools your body down - albeit 35°C. By the way I shower with ~42°C regular lol
Upvoting for visibility, but this seems insane and impossible to me. When I take a cold shower, I can feel the water stealing the heat from my back, because it's warmer when it hits my legs. It's crazy.
It's definitely taking heat away, for me, and I would die if I tried to take a hot shower on a hot day.
I start with a warm shower, like normal, then slowly turn it down until it's nice and cool, almost cold. But not ice cold. Feel way better afterwards.
Biologically: being hot all over makes your capillaries close to the surface of the skin expand so you can dump heat into the air quicker
A hot shower raises this above ambient, giving you even better capillary cooling for a while, plus hot water tends to evaporate quicker, taking more heat load with it.
You know what's funny? I have experienced the inverse of this. I run pretty cool so always take warm or hot showers, but one time there was a cold snap and my water heater broke. We had well water so it was very cold, and down here we do not really have heaters designed to handle actual cold so the house was freezing too. So I had what was probably the most uncomfortable shower of my entire life, shivering and teeth chattering so fucking cold, thought I would die, but when I got out? The air felt almost warm, it was so pleasant not just because it was over, but because it somehow blunted the feeling of cold. I don't understand how chilling my core somehow warmed me (it usually works the other way) but it sure did.
At night here I do shower hot, I think the theory is that then when you lay down, your body temperature is dropping and that makes it easier to fall asleep.
I am fortunate to have moved to a climate where the heat is less severe and when it is hot it tends to be dry-ish. My house does not have AC so we put a big exhaust fan on the top floor and crack a window downstairs. Works so far, but we have some small portable AC units for the bedrooms just in case we need them.
Having lots of trees around the house will keep it cool but cause lots of other problems. Solar panels and AC is the way to go.
Not really a thing you can just do, but thick walls. I live in an old house with double layered exterior brick walls. It has such a massive impact that sometimes I wear a vest inside, while it's heatstroke temperatures outside.
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.
Just get AC, it works so well for de-humidifying too.
But otherwise blackout curtains can help a bit but also radiate heat themselves.