How to keep a room cool in hot-humid weather without air conditioning (science!)

I keep my windows open and use a fan,blinds lowered.

Open the window, put a fan by it and put a cool towel over the back of the fan. I’m not sure how well that works in humid conditions, but here in non-humid California before we got an AC unit for the garage that’s what I did out there. Seemed to help.

Put a reflective film on the windows. 3M make some that will keep the light/sun out of the room.

Open and ventilate the room with the LARGEST fan at night

How hot is it outside? If it is 90+ I would keep the windows closed in the middle of the day. Keep some fans going. You can buy a dehumidifyer.

Like this.

Take a coil of thin copper pipe, attach it to the front of a fan in the shape of a spiral. Attach to one end an aquarium pump, which you put in a cooler full of ice and water. The other end should empty back into the cooler. By pumping the cold water through continually it cools the air near it, which is blown around the room by the fan. Should use less electricity and cost less initially than an AC unit.

Edit: Okay, apparently @Fiddle_Playing_Creole_Bastard and I posted the same idea at the same time. :P

Depending on the layout of your house, it may be possible to create a cross breeze by opening certain doors and windows.

stay hydrated and eat cold food

Open up for cool air at night and close the windows and blinds during the day.

It depends on the room though. Some places heat up from sunlight on the roof.

You can pick up a brand new window A/C unit for around $200, I’m sure you could find a used one for much less on craigslist or ebay.

I have new (two years old) extremely well-insulated windows, and they’ve made a remarkable difference in keeping the house warm in winter and cool in summer. On hot days I keep them closed all day, and when I walk in at the end of the day it is noticeably cooler inside.

Later in the evening (assuming it cools) then I’ll open them and turn on the whole-house fan (large attic fan) to do an exchange of inside air with the now-cooler outside air, and usually keep the windows open all night.

There’s evaporative cooling, which works if the room isn’t too humid. The simplest method is to inject liquid water in front of a fan, lowering the temperature by evaporation. It works best when the relative humidity is low. In the US these are sometimes known as “swamp coolers.”

I believe the worst thing to do is run a fan with the windows closed. It turns your house into a convection oven, kind of.

Get a folding screen to put in front of the window. The window is open and the blinds shut enough to cover what the screen does not. Put the fan behind the screen to cut the noise from that too.

Once the outside temp falls below the inside (late afternoon / early evening) it would help to have window fans blowing outward to vent warm air and draw fresh, cooler air in from another open window or an open door.

As for the blinds/window dilemma of keeping out the sun while admitting a breeze from the window: Depending on time of day and direction the window faces, there should be some optimum setting for the angle of the slats to completely block out direct sun (sunlight cast on the floor will almost disappear) while hopefully remaining horizontal enough not to block window airflow. You might have to tweak it every hour or so until sunset.

If you have sash windows that open vertically plus horizontal blinds, open the window and set the blinds to cover only the closed portion of the window. Again there might be some optimum trade-off between window opening and sun-blocking.

Eating really cold food and drinking icecold drinks will actually require your body to burn more calories and your sweat transfers the additional heat into your room which could make a difference if it’s small. Human beings are like 100 watt light bulbs. So lukewarm food and drinks are better. Besides, setting your fridge to extra cool will heat up your room even more.