What are some easy ways to stay cool during the day without using electricity?
I think the first thing that comes to mind is what you can do to decrease the temperature around the home in the summer. I am here in Jakarta, Indonesia at the moment and I have found that covering the patios with container gardens has a remarkable impact. Beyond this, well-placed trees, and the like, can help a lot. If you compare the house where I am living to my mother-in-law's place across the street, without air conditioning there is no comparison. Even in the middle of the day my house is quite a bit cooler.
When I am in Chelan,Washington the summer temperature is often hotter still, but can do ok without an air conditioner if needed (we have one smallish window-mount).
The second thing is to pay attention to air flows. A couple of open windows can be used to generate breezes. Air flow is absolutely important.
Cold slowers/baths are good. I would add that sometimes the simple act of putting water on one's head can help a lot. If you live near a body of water, swimming helps too.
The bad news is that if it is hot enough none of this is "easy." It takes effort, paying attention to detail, and the like.
Another approach is to leave windows open at night and close them in the morning for as long as you can, closing blinds etc. to reduce the amount of sunlight-driven heat in the home.
In the end these are all techniques. What you do to make it all work depends on a combination of them.
Solar gains account for over half of a typical home's cooling requirements in the northern United States, so shade your windows--preferably from the outside, using awnings and plants. While curtains and window shades will help some, sunlight coming through the window will heat the shades. When the shades heat up, they will transfer some of that heat to the air in your home. Light-colored roofing materials will also make a difference.
If you can't take major steps like that, a wet bandana can make a big difference in how you feel.
I am in Thailand now, it is the hottest time of year, relentless 40C and sun every day. No air conditioning.
I survive by staying indoors during the hottest time of day, getting my clothes wet. Sitting close to the ground can help. I find ceiling fans unhelpful as they bring down the hotter air that has risen to the ceiling.
Your body adapts to heat after about 2 weeks so it is good to let yourself get as hot as you are comfortable with. This is why air conditioning is bad, people overuse it and are less able to cope with heat.
Use the middle of the day for relaxing, sleeping or other non physical activity.
The locals here play cards when it is hot.
I developed a simple strategy suitable for living in a flat that is not on the top floor:
- When you wake up, close all windows and put the blindfolds down. This allows to prevent sun rays and hot air for getting in. If you can install some cover on outside of the windows, that would be way better. Aluminium foil would be best but it's ugly.
- When you come back from work, open all windows once (if) it gets cold outside. I used inside/outside thermometer. Once I saw the outside temperature is lower than inside, I'd open all windows.
The effect is not awesome, but I could assure up to 5 degrees Celsius difference between outside (in shadow) temperature and inside. And it's really not much work and has zero money investment.
As far as cooling oneself, when it was at it's worst, I'd take a cold shower. I really hate cold water, so I'd do it only when it was really bad, but if you're more tolerant to it than I am, this is something I'd recommend. The effect is profound and can last up to an hour, which can be just enough to survive the worst wave of heat.
I have gone for an entire summer without using electricity. The fastest way to cool down is to take a cold shower or to keep your bath tub filled with water and take a dip when it gets too hot.
Also it is sometimes difficult to sleep when it is both hot and humid. To solve that I had to step out of the cold shower without drying off, and falling asleep while wet before it got hot. I would sleep right through the night.
Around 4:00AM the humidity would drop until about two hours after sunrise. This allowed for cool blissful morning breakfasts.
To keep body cool on hottest summer days, I use wet tee-shirt so as to mimic body's natural cooling system e.g. transpiration. Vaporisation of water really helps to feel good even under full sun. For the sake of not using too much tap water I found empirically that wetting at neck and upper back is most water-efficient while achieving good results.
At night it is possible to get asleep while wearing such wet clothes too.
Keep in mind common cotton wet clothes let most UVs pass to skin. Use anti-UV wet clothes or UV-cream under wet clothes under the sun.
Of course it is necessary to wet clothes once every hour or so.
I agree with the above answers but also depending on your location the results can vary. If the air is hotter outside than inside, opening windows can hurt your efforts. If this is the case and your house is in direct sunlight covering the windows during the day can decrease the amount of absorption significantly. If your house has many floors it is crucial to pay attention to "heat rises". Directing the flow from a lower floor to the top open windows will push the heat out.
Cooking is also an often ignored heat source. Barbecue, use an outdoor oven etc can help. And paying attention to other electronics as heat sources is important. Turn off and unplug what you aren't using.
If you are in a dry environment, water will cool you.
This is the idea behind the arabian turban. It could be put on wet, and evaporation from it's surface cooled the mass. (I don't know if the sikh turban is used this way...)
I've done this on outdoor trips with a plain canvas hat. Saturate it in the lake and place on my head. With the smaller capacity, it needs to be redone about every half hour.
Water can be cooled below ambient temp by evaporation. This is the idea behind canvas sided water bags that slowly oozed water. The surface was wet, and so the water temp would be somewhere between the drybulb and webbulb temperature.
Putting on a wet t-shirt can help. It can be gaspingly cold if your water supply is cool.
Moving air helps. Ceiling fans draw 12 to 70 watts depending on how fast they are turning. At their slowest speed, they move water saturated air away from you. At higher speeds, they speed evaporation from your skin. This does use electricity, but not much.
As temperature approaches body heat, and humidity becomes higher all of these are less effective.
If it's new construction, building underground should be considered. Ground temps even a few feet down are close to the yearly average temp, rather than the daily high. Even if only part of the home is underground, it can give respite. I grew up in northern Idaho where August was 105 to 110C. In the afternoon we'd retreat to the basement where it was 25 F cooler.
White is your friend. When out in the sun, thin white clothing is more reflective than skin is. Plus cloth doesn't get skin cancer. Again, look at traditional Arab dress. Such clothing should be loose and thin so that air circulates under it easily.