lot of useful stuff here, I'll ad my two cents, because nowadays we get 42 C ( 108 F ) summer heat here, which is measured in shade over a grassy area... this also means walking the dog when the sun is out is impossible, as the concrete usually heats up to temperatures that will cook eggs and also poor doggos paws.
so what I figured to keep your home cool is to disallow heat to access it, and remove heat if it did. from what I gathered in the recent years is
1, do not allow the sun to touch your house. this has the huge caveat of having to have control of the house, which is, if you live in an apartment, is not possible. but, if you live in a detached house, you need to make sure that the sun doesn't reach the roof and walls, most useful is trees, that block the sun in the summer time, but the leaves will fall in autumn so you'll have some heating from the sun in winter. you can also use tarps, mylar or anything the sort, just mind where you reflect the heat and light, you don't wanna boil your neighbor.
2, if the light touches the house you need good insulation, so it won't seep heat into the structure itself. I don't know how well north American house structures can store heat, as they are made out of wood ( mostly, afaik ) but here we have brick walls, so you need to have thick insulation on the outside of the structure to avoid heat going in ( or out at wintertime... ).
3, block sunshine through the windows
from the outside . we use roller shutters, but anything that blocks the sun but won't transfer heat into the window itself should be okay
4, if the heat already reached the inside of your home, try to manage the perceived temperature, move the air around, and try to keep the air as dry as you can, if you've been to the desert you'll recall that 38C/100F in the basically zero humidity is perfectly manageable, you only need to remember to drink a LOT. also try to keep the heat sources inside the house to a minimum, so try to use the least amount of dryer, stove, tv, pc, basically anything that generates a lot of heat.
5, Move the air! Opening the windows at night can be useless if there is no draft , so always pay careful attention to actually have the air move through the home, if your home has draft naturally, great, but you might want to place a high throughput fan in one window pushing air in, and in another room sucking air out. this has helped me tremendously at summer night times when air just basically stagnated inside, so even though it was colder outside, it didn't get any colder inside .
+1: if it can applied, running a drip irrigation system close your windows can allow the grass to be cool, hence the air entering through your windows will be cooler, but this assumes basically wasting water for a bit of relief from the heat, so not ideal
as other mentioned, closing your dwelling to the outside during the day, and opening everything at night is a good idea, but as also others mentioned, sometimes even the evening temperatures are way too high, so this might not work at all...
so what can you do if you already have hot air inside? from worst to best, here is my experience:
- swamp cooler: basically just blowing air through a wet piece of material, it WILL cool down the air a tiny bit, and also it will even filter the air, so great for catching pollen and dust, however... Mold. It will increase humidity, which will eventually decrease your comfort , and the water and the filter - or the material you blow through air - will develop mold, so you'll need to manage that and keep a close eye on what you're breathing in
- simple fans: great when you just need a bit of cooler feeling, but when the temperature reaches a certain point, you're just sitting in an air circulated oven, it feels much worse to have hot air blown at you
- portable AC: fairly OK, but most of them literally sucks, meaning it will suck air out of the room it's placed in, there are countless information on them why they are not the greatest solution, but sometimes that's your only way to introduce cold air into the area you're in
- window AC: one of the best available options, but can get fiddly, also here the price is the same as a split AC unit, so if possible, a split version is favourable
- split/central AC: the best bang for buck ratio, only caveat I found that it can dry the air too much, leaving you open to more respiratory diseases , but with some simple air humidification ( not sure that's a word ) you can manage just fine, also you can use it to heat your home come winter time
- heat exchanger cooling: fairly complex, you need two drilled wells, you bring water up from one, into the heat exchanger, blow cool air inside, dump heated water into the other well. requires very little maintenance, consumes only the fraction of the power of an AC, and can supply 17 C / 62 F cold air throughout the summer for cheap. the issue with this is obvious, you need two wells, piping to and from your heat exchanger, a heat exchanger ( if you're heating isn't connected to one ) , but if possible, this is one of the best solutions you can get long term, you can use it in the winter as well to help out a bit for your heating needs if designed properly
- geothermic air conditioning: same as the previous mostly, but instead of wells you have a closed loop of liquid pulling the heat from the house and dumping it underground, uses a tiny amount of power comparatively, reliable and sustainable, but the initial cost is just astonishing... or at least here. you need to place the pipes deep down the ground, for that you need to move the earth quite a bit, and you need very high quality pipes, that can lay in the ground for years and years without leaking or bursting. this is basically the going down in to your cellar to cool off, just bringing the cellar up to the attic as well, it's great in all aspects, other than the price
one thing I've been messing around recent days is an actual 'personal AC', which is basically running icy water through a coolant radiator and pushing the cold air at you, like so:
I'm still waiting for some parts, but I'll report back how it goes
