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Comment by roelschroeven | Hacker News Reader

A couple of years ago that would have been correct, but circumstances have changed.

We've had a series of heat waves this summer, and temperatures have gotten very high inside. Much depends on the location of course, and the type of building, and stuff like that, but the fact is that in Belgium alone thousands of people have died because of the heat. Thousands of people that would still be with us if they would have had adequate cooling.

When it's close to 40 °C in your home, a ceiling fan is not going to make a meaningful difference.

And we need to keep in mind that summers are in all likelihood going to get hotter and hotter.

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Around and above 40°C, fans _are_ worse that useless - they may actively be killing you instead.

> Use electric fans only when temperatures are below 40˚C / 104˚F. In temperatures above 40˚C / 104˚F, fans will heat the body.

- https://www.who.int/news-room/fact-sheets/detail/climate-cha...

> When it's close to 40 °C in your home, a ceiling fan is not going to make a meaningful difference.

Hottest the hottest south facing room in my house got in the UK this year was 31.8C on the 13th August.

The loft got upto 43C, but that's what insulation is for.

That said, you're right, things are changing. I'm looking at getting AC installed this winter (no way I was paying summer prices).

How is the inside of your home getting to 40 in Belgium? Our hottest recorded air temperature was 36 this year.

There were many excess deaths, but there was also a shortage of fans here. Good fans could have also saved their lives.

Air temp is measured in the shade, sun hitting windows/interior floors would take you past that.

IR blocking film/tint on outside works great if you can't get windows shaded.

I live in the Netherlands. My apartment has two floors. The upper floor is basically a greenhouse, so 40C is absolutely normal if I close the windows. During the summer I always keep at least one window open, which cools down the house to around 30-35C. This sucks during summer but during winter it's a blessing because I can have 30C on a sunny day even if it's 0C outside. The only drawback is that the windows are very old so in winter that heat escapes immediately once the sun is gone. HOA has been planning window replacement for years already.

The lower floor has windows facing north so it's always much cooler there. I've never seen it reach more than 30C, which was in the middle of a heatwave, usually it keeps 25C during summer.

> During the summer I always keep at least one window open, which cools down the house to around 30-35C.

Yeah this is exactly my point. If your house is so poorly insulated that your internal temperatures go above the ambient temperature, you can open a window.

Chances are that ambient are doesn't provide enough cooling. Maybe you can open only window, or all windows on the same side of your home, meaning there's no draft. Maybe you're in an urban environment, with a micro climate even hotter than outside the city. Maybe both. Heat will enter from sunlight and from people inside, and will exit only very slowly.

There's a world of difference between a house in the countryside, with maybe even some trees providing shade, and an apartment in a densely populated area with very low opportunities for thermal control.

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