A lot of heatwave "wisdom" is just plain wrong, and following it wastes effort, money, and comfort. Let's debunk the most common cooling myths and replace them with what actually works.
Myth: A fan cools the room
Reality: A fan doesn't lower the air temperature — it moves air, which cools your body by speeding up sweat evaporation. That's why a fan blowing in an empty room does nothing, and why it feels great aimed at you. Use fans to cool people, not space, and turn them off when you leave (see our fan science explainer). The one exception: a fan at a window at night genuinely exchanges hot indoor air for cooler outdoor air.
Myth: An ice-cold shower cools you best
Reality: A lukewarm shower beats an ice-cold one. Very cold water can cause your body to constrict blood vessels and conserve heat, leaving you warmer once you're out. Cool-to-lukewarm water lowers your skin temperature without that rebound. The same goes for drinks — cool, not ice-cold, is the sustainable choice.
Myth: Leave the windows open to let air in
Reality: During the hot day, open windows let hot outside air in, making your flat hotter. Keep them closed and shaded while it's warmer outside than in, and open them only at night when the air finally cools (see our Stoßlüften guide). Timing, not just opening windows, is what cools a flat.
Myth: A bigger air conditioner is better
Reality: An oversized AC short-cycles — cooling the air fast then shutting off before it removes humidity — leaving the room cool but clammy and wasting energy. The right-sized unit for your room runs steadily and comfortably (see our BTU sizing guide). Match cooling to the room, don't just buy the biggest number.
Myth: Indoor curtains block as much heat as outdoor shading
Reality: Outdoor shading wins decisively, because it stops sunlight before it passes through the glass, while indoor curtains act after the heat is already inside. Curtains help, but if you can shade from outside, that's far more effective (see our shading comparison).
Myth: Air coolers work everywhere
Reality: Evaporative air coolers work well in dry heat but poorly in humidity, because they cool by evaporation, which needs dry air. Buying one for a humid climate disappoints (see our humidity guide). Match the device to your weather.
Myth: You just have to suffer through it
Reality: With the right habits and gear, most heatwaves are very manageable. Shade and seal by day, ventilate at night, cool people with fans, keep one room as a retreat, and add the right cooling device for your situation. You don't have to suffer — you have to do the right things.
The takeaway
Don't waste a summer on cooling myths. Cool people not empty rooms, take lukewarm not freezing showers, ventilate only when it's cooler outside, and size cooling to your room. Armed with what actually works, check what's in stock near you and stay genuinely cool.