Ask Lemmy

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.

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.

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.

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.

Related

Apparently window awnings make a considerable difference.

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.

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.

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

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.

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):

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.

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.

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.

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.

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.

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.

From a Deep South transplant who went through plenty of hurricanes with no electricity, a frozen gel pack between your thighs. You’re welcome

Open upstairs windows after 8-9 PM to let cool air in, blackout blinds work really well too

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.

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

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.

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.

Live somewhere it doesn't get hot.

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