That percentage varies drastically by climate region — see the map above, from a survey conducted by the Energy Information Administration. Home AC rates — including both window and central units -- range from 38 percent of households along mild stretches of the West Coast to nearly 100 percent in the Deep South.
I'm one of the proud 16 percent without AC in the "cold" region, which basically encompasses the northern half of the United States. Here in Northwest Minnesota, two hours north of Fargo, the temperature is currently 30 degrees cooler than it is in Washington. It's perfect! Summer should never get warmer than this. But even here, the mercury cracks 90 from time to time, so I've been looking for ways to keep the house cool in the summer without AC.
As it turns out, the federal government has done a ton of research on the topic, primarily in the interest of keeping energy use low. But a lot of these guidelines, and some of the life-hacky "12 tips for keeping cool in the summer" stuff you read online, involve making radical changes to your home, like growing shade trees over your house or installing a whole house fan.
All of which is great advice, if you've got 30 years to wait for a tree to grow or if you've got a few grand to drop on a contractor. But it's not particularly useful if it's 95 out and you need to cool off, like now.
So to that end, I've scoured the federal government's publications on home cooling to find the guidelines that are actually practical for the average schmoe like you or me. Someone who either lives in an apartment and can't make major changes to their home, or who is either too cheap or lazy to do so. Someone with maybe a few bucks to spend on a fan at Home Depot, but who doesn't want to blow thousands of dollars on byzantine alternative cooling systems. Someone who needs to get cool right. now.
Note that you don't have to be an anti-AC fundamentalist to make use of these — use them to supplement your air conditioning and you'll probably shave a few bucks off your summer electric bills.
1. Shut it all down before you leave for work.
During the daytime when it's getting hot out, shut your doors, shut your windows and draw your curtains or blinds as tight as can be. Your home has probably cooled off overnight, which means that soon the air outside is going to be hotter than the air inside. You want that air to stay out for as long as possible. Don't let it in.
If you're one of the lucky few with exterior shutters or awnings around your window, shut them! These are much better at blocking sunlight and heat than interior shades. If you have curtains, you want them light-colored and as tight against the wall as possible to reflect heat.
Per the Department of Energy, "A well-insulated house will gain only 1°F (0.6°C) per hour if the outside temperature is 85° to 90°F."
And it works best if you keep that outside air outside.
2. Open it all up when you get home.
As soon as it feels cooler outside than it does inside, fling those windows wide open. This will start to flush out all the hot air that's built up within your house during the day, replacing it with the cooler outside air.
Conventional wisdom states that you want to open windows that are across from each other to get that nice cross-breeze effect going. But this isn't optimal! "Inlets and outlets located directly opposite each other cool only those areas in between, in the direct path of the airflow," according to a 2001 Department of Energy publication on "ventilation strategies." "You'll cool more of your home if you force the air to take a longer path between the inlet and outlet."
One way to do this is by opening up the windows at the lowest and highest points in your house. This creates a "chimney" effect: Cool air enters the house through the lower windows. As it heats up, it travels upward and eventually vents out the upper windows.
Depending on how the wind is blowing, you're likely to find that breezes tend to blow air in more on some sides of your house than others. Experiment! Open some windows, close others, see what produces the best air flow. You may find that having a smaller window opening where the air blows in, and a larger one where it blows out, produces the optimal breeze.
3. Now that you know how the air is blowing, give it a hand with a fan.
"When you know how air moves naturally through your home, you can then optimize your mechanical ventilation," the Department of Energy writes. If you're gonna stick a fan in a window, make sure it's blowing with the natural air current, not against it. You can also use a fan to blow air out of the windows where the air is naturally venting.
If you have multiple levels but only one window fan, put the fan on the top level blowing out to get that chimney effect going.
If you're taking a shower, be sure to use your bathroom fan to blow that hot, humid air out of the house. Ditto if you're cooking on the stove and have an exhaust fan that vents outside.
All other things considered, it doesn't really matter much whether you're blowing the hot air out or the cool air in. The important thing is to blow.
4. Use your basement.
Do you have a basement? Head down there. Chances are it's about 20 degrees cooler than it is upstairs. Put that cold air to use! Prop the basement door open and stick a big ol' box fan right there to suck the cool air up to the main levels.
Want a slightly fancier solution? Get one of those mountable industrial fans that you can bolt on to the wall or ceiling of your basement stairwell and set it to blow the air up. Just make sure it's in a place where you're not going to knock your head on it every time you go downstairs.
5. Turn off lights and other heat-generating things.
A fair amount of interior heat can be generated by things like light bulbs (especially incandescent and halogen bulbs) and some appliances. Put your hand near any light bulbs, electronics or appliances. Does the air feel warm around it? Can you do without it for now? If so, switch it off or unplug it.
Same thing with computers: If you're watching Netflix on a laptop on your lap, you're probably giving yourself a double-dose of heat. The laptop is physically warming your legs, plus if the fan's going, it's blowing that hot air out into the room. Put the computer to sleep if you're not using it.
This is kind of obvious but if you can, cook on a grill outside instead of a stove inside. If that's not an option, use the microwave instead. If you have a dryer, run it at night when it's cool, or put off laundry for a few days until the heat breaks. Ditto your dishwasher. If you have a few bucks to burn, consider replacing older incandescent or halogen bulbs with newer CFL or LED bulbs that put off less heat.
6. Cool thyself.
If you're confident you're doing all you can to cool the whole house down, it's time to think about making yourself comfortable. Ceiling and table fans are great for this — they don't actually cool the house, but they make it feel cooler. If you're fortunate enough to have a ceiling fan over your bed, run it when you're sleeping — this will make the air feel about four degrees cooler than it actually is, which can mean the difference between sweaty tossing and turning and a good night's sleep.
No ceiling fan? No problem: Get a table or box fan and point it right at yourself when you're sleeping, which should provide close to the same effect.
7. If all else fails?
Look, there's a limit to just how much cooling you can do naturally, especially if you live in the humid South or if you're stuck in one of those horrible heat spells where the temperatures don't dip below 80 degrees at night. If it's unbearably hot and there's no AC, wet a cloth with cold water, drape it around your neck, and point a fan right at your head, as Christopher Mims suggested in Grist a few years ago. You may end up with a damp spot on your couch, but by that point you won't even care.
Got any cheap and easy cooling tips that I missed? Drop 'em in the comments.