It is too hot here. Nearly touching 40°C. And I cant afford to buy an AC or a Cooler right now. So, what would be the best substitute which I can afford or can make by my own?
Most people won't have the materials to do this, but you can mimic a swamp cooler. You need flowing cold water for best effect, but static water or ice is better than nothing. If you have some sort of fountain you will place a fan right in front of that blowing on you. If too much water is getting on the fan you can put an air filter in front of the fountain and behind the fan, the type you should have in a furnace or ac unit. They are cheap, like $1 each, if you don't have one and need one.
You could make your own swap cooler by making a recycling water fountain to soak one of those filters. Another filter about 2 inches away from that one that isn't getting soaked, and then a fan directly touching the dry filter blowing away from the water. You'll have to look up making a fountain though as I don't have any real experience with making one.
The idea is for the water to cool off the air being sucked into the fan and subsequently blown into you.
The colder the water and the more water that flows over the filter the better it will work.
Edit: also if you can find a filter that is more porous, or has larger holes, you will get more air flow and thus cooler air.
Edit: this video here is almost exactly what I described, or at least pictured in my head. The second air filter I mentioned was just to keep the fan from being saturated from splashes and thus dying.
Ok so this question has been around quite some time. I'm going to answer anyway since the most effective way - from my experience - hasn't been mentioned yet.
There are lots of ways to help you deal with the heat. Which one(s) help most depends a lot on your circumstances.
Keep your room/flat/house as cool as possible
Open all windows at night. Close the windows and all blinds, shutters, etc. during the day (around sunrise). If you have to get up earlier than usual to do this, do it anyway - sleep a few more hours afterwards if you want to.
How much this helps depends of course on the temperatures at night, the insulation of your house and on whether you have shutters on the outside or only inside. If your insulation is good, this is a very effective way to keep your house cool: doing this helps my parents keep their house 10-15°C colder than the outside right now. I live in a flat on the top floor and only manage 5°C less, but it still helps enough to make the temperatures bearable (we had a few days around 37°C recently).
Open the windows only if the room is already as hot as the outside and if there is some wind going.
Evaporation is your friend
Evaporating water cools down the air. Evaporation happens faster the drier the air is and the more the air moves. To use this you can:
- Drink a lot to help your body produce sweat. With high temperatures you need to drink more than you usually would. I find that keeping a jug of water with some lemon and mint nearby helps me drink much more.
- Wear a damp shirt, keep a wet cloth around your wrists or neck, don't dry your hair after washing, etc.
- Use a fan (electrical or just hand-held, a magazine, newspaper or even a normal sheet of paper can be a reasonable substitute).
Other ways to help your body keep cool
- Don't do sports or anything that causes your body to produce a lot of heat.
- Wear loose, light clothing.
Find some cooler place to be
- Might be a good time to visit that new museum, go to the cinema or theatre, eat at a restaurant with airconditioning, ... But be careful when moving between places with and without airconditioning, especially if your circulation is weak.
- Or go swimming, but make sure to protect yourself from the sun (e.g. cover your head and consider wearing a t-shirt).
- Do you have a cellar? If so, put a comfortable chair down there and enjoy the cold.
- Go into a forest. Trees also evaporate water, and there is shade.
Change your normal routine
Get up early and do anything that requires physical work or concentration. Maybe have a siesta in the early afternoon when it is hottest. Use the evening if you have more you need to do.
Mostly just make yourself feel better
- Get a bowl with cool water and put your feet inside.
- Eat ice cream or fresh fruit.
- Don't wear too little: sweaty skin on sweaty skin feels worse than with a thin layer of clothing inbetween.
- Put bread, fruit and vegetables in the fridge if you don't do this already. It really doesn't help to find that something has gone mouldy in less time you'd expect it to take - and then you have to go out into the heat and go shopping again ...
Your own body can be very effective cooling you if the humidity is low enough.
A de-humidifier uses coils cool enough to pull water out of the air by condensation. Then, the drier air in your environment will seem much cooler than the humid air at the same temperature.
Although you don't need to vent a dehumidifier to the outside, you'll need to periodically remove the water that accumulates as the unit runs. It also uses less power than an air conditioner and makes less noise in operation. It's a great practical alternative to an air conditioners.
Any cool water bottle or chilled soda pop can pressed up against the neck will cool you down. You alternate left and right side every few minutes. The idea is that the cold fluid against your jugular vein on the left hand side cools the blood entering the brain whereas the right hand side cools the blood exiting the brain and returning to the body. In addition to drinking plenty of fluid until such time as you begin the core of your body return to normal. Don't rely on being thirsty as an indication of level of hydration. You could be dangerously dehydrated well before you become thirsty. Also find shade.
If at home you can lie down on a sofa or bed with a fan on you. Lying down you lower the amount of energy you produce and therefore help in cooling. You can spend some time in a tub filled with cool water. Start with tepid first then gradually added cooler water up to your tolerance level.
A spray bottle of water.
(Ignore these additional nonsense characters added 'cause site doesn't like short answers.)
I did quite some experiments myself as I have spent several hot (up to 39 °C outside) days in a campervan type vehicle with no air conditioner. The most important measure turned out to be "cool down everything during the night as much as possible", as already mentioned in another answer.
Here's my most effective measure for when the air is already hot inside, and it has not yet been mentioned in this form: direct a fan at wet clothing or wettened skin. This method is crazy effective as it increases evaporative cooling (as if by sweating) a lot, but only if humidity is low to moderate. In my test with an IR thermometer, blowing a fan on wet fabric resulted in a temperature drop from 31.1 °C (the surrounding air temperature) to 23.5 °C. With this method, I was comfortable in 32.6 °C air, and pretty surely would still be in 34 °C air.
Be careful with this, though. Cooling the torso, chest or neck may result in or promote respiratory issues and for that reason I don't do it anymore. Instead, I do it like this:
I wear a dry (!) T-shirt while applying this method, to prevent any respiratory issues / infections due to excessive cooling at the torso.
To wetten the face and arms, the most comfortable solution so far is a bottle with water, a plate and a fresh washcloth. Put the washcloth on the plate, pour some water on it, and wipe the face, arms and legs with it regularly (every 5-8 minutes or whenever the cooling effect wanes).
You can also wetten the hair on the top of the head. This is no good idea however when working at the computer, as drops of water may fall on the keyboard etc..
Keep one or more fans directed at the wettened skin.
Keep safe from legionella by using clean water and fresh clothing. If in doubt, treat the water with chlorine based water disinfectant before.
My next improvement would be special clothing for arms and legs that can soak up water quite a bit and will distribute water supplied from a reservoir at the upper arm / leg to the rest of the fabric. This would remove the need to regularly wetten the skin.