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New Worlds: Keeping Cool

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Although I may differ from the people around me as to when it’s gotten too hot, I agree with them on one thing: it’s more difficult to cool off than it is to stay warm.

In fact, we’ve only very recently reached a point where we can actually cool the air around us. The first thing we’d recognize as air conditioning (which not only chills air, but removes humidity as well) was invented in 1901. There were experiments in that direction all the way back to the sixteenth century, when scientists began to use chemicals either to cool water ice well below its normal freezing point, or to use evaporation to chill objects, but for commercially useful A/C, you really need electricity.

So what did people do before then? Did they all just marinate in their own sweat?

In part, the answer is “yes.” Most of us take for granted the ability to regulate our environment, but our ancestors didn’t; they had to play with the cards nature dealt them. Although you’ve probably seen movies where some queen or emperor lounges around with servants or slaves waving giant fans, that doesn’t really cool the air; it just moves it, which helps us feel cooler via the evaporation of sweat. (Meanwhile, the person doing the fanning overheats.) The same goes for electric fans nowadays. They help, but they don’t address the root of the problem.

Rich people sometimes had other alternatives, though. Depending on regional conditions, they could import ice: packed in straw and stored in a cellar, it’s possible for that to last a surprisingly long time. Of course, you don’t want to go hang out in a cellar full of straw and ice . . . but you can have your servants hack off chunks to chill your drinks, or put them in your bath, or simply let them melt near you to cool the air. Have a servant fan across the ice block toward you, and you’ll get at least a little relief.

Even if you couldn’t afford that — and most people couldn’t — there were still some possibilities. Go back to that cellar; anything stored down there will be cooler than upstairs, and cooler still if you can store it in a cistern or other body of water. Even an earthenware jug can provide a bit of chill: its porous walls allow tiny amounts of liquid to filter through, which evaporate and thus cool the rest of the jug. An experiment discovered that under optimal conditions, this can reduce the temperature of the liquid by as much as fifteen degrees Celsius! That’s enough to feel seriously refreshing on a hot day.

Going back to those bodies of water . . . they’re a mixed blessing. While they do cool the air, they can also increase humidity, which most people feel makes the heat worse. (Not everyone, though. I used to believe everybody thought a dry heat was better, until I met several Malaysians who felt strongly the opposite.) Bodies of water, especially still ones, are also a breeding ground for insects like mosquitoes, who bring their own form of misery.

As with keeping a building warm, there are architectural ways to help with cooling. You want to keep out the light, while encouraging air to move through. Deep eaves that shade the walls, at least at some times of day, reduce the amount of solar heating the building suffers. Porous screens, whether made of tied reeds, intricately pierced wood or stone, or modern materials, provide some relief as well. You can put a covered breezeway through center of the building; especially if you open windows in the adjoining rooms, that can draw cooler air into those rooms from outside. Of course that only works when the air outside is cooler, but it can make a significant difference after the sun goes down. I can attest to that technique personally, as it’s how I manage the temperature my own (non-air-conditioned) house on hot days.

In the ancient Mediterranean, many houses were built around a central courtyard. Much like a breezeway, this provided fresh and often cooler air to the surrounding rooms — but it’s important to remember that the courtyard was not generally a bare stone expanse. That would only radiate the heat back at residents, making things worse. Instead the courtyard was usually a garden, often with a catchment pool for rainwater, which mitigated the effects of the sun.

We should take note of that last point, because it’s one we’re having rampant problems with nowadays. Our cities are giant heat islands: our streets and sidewalks and buildings absorb heat during the day and continue to radiate it at night, making air conditioning more necessary. (Air conditioning which vents hot air to the outside, thus compounding the overall problem.) Neighborhoods with more greenery can be ten or fifteen degrees cooler than those without, which has health consequences for residents in poorer, less landscaped areas — the same people who have a harder time paying for A/C. It’s not just an aesthetic fad when you see cities of the future incorporating living roofs and other green designs; measures like those can help regulate the temperature of an entire city, making individual homes more livable.

Furthermore, we can adapt our behavior to the demands of the climate. It’s common in many tropical areas to have a siesta; though the word is Spanish, in English we apply it to all kinds of midday breaks. Rather than courting heatstroke during the hottest part of the day, why not spend that time in the shade, maybe with a cool drink from the earthenware jug in the cellar? Work can be done in two phases, morning and evening, when the world isn’t quite so stifling.

Even clothing can be an adaptation — and I don’t mean by stripping down to our skivvies. Lightweight, breathable fabrics won’t cool you off, but they can at least minimize the amount of heat you trap against your skin. And, counter-intuitively, sometimes more clothes can actually help. If you’ve ever seen a picture of a Bedouin in traditional dress, you know they wear long black robes, which would seem to be exactly what you don’t want on a searing desert day. But thermal studies have shown the black robes stop more short-wave radiation from reaching the skin than white ones, while the loose fabric allows for more air circulation. Even if you’re not going to swathe yourself in a robe, merely putting on a hat can significantly reduce your risk of overheating.

As our planet continues to warm, we may need to remember more of the low-tech solutions to keep ourselves cool.


6 thoughts on “New Worlds: Keeping Cool”

  1. It feels real good to sit on a radiator on a frigid winter day. But it doesn’t feel good to sit on an ice block on a hot summer day.

    1. Howard, that seems more because of the difference between human temperature and the temperature of what you are sitting on. In °C , human temperature is about 38°, while ice melts at 0°, so that will be a temperature difference of 40° or more: if the ice comes from a freezer at -20° that’s a difference of 60°C!
      Central heating water temperature needs to be at least 60°C to avoid Legionella bacteria being able to grow in there, but not hotter than 90° to avoid bubbles forming when it gets too close to boiling. So it’s usually set somewhere around 65-70°, a difference of 25-30°.
      Winter clothes are thicker and insulate better than summer clothes, so combine a better insulating layer with a smaller temperature difference, and it’s clear which option will be less uncomfortable.

  2. Yes to hats in hot weather! When Thor and I were visiting Lindos on Rhodes island, a heat wave made the labyrinths of white buildings an oven. We always wear shade hats in such climes, but came upon a hatless woman clearly suffering heat stroke. Thor had just bought a chilled bottle of water and offered to pour some on her head and neck. She was grateful! And we advised a hat….

  3. typo: through center of the building

    Mideast architecture has a bunch of neat tricks; I think the windcatcher is a more specialized version of the breezeway you mention. Of course these exploit dry-ish heat, with big diurnal temperature swings, not the constant high heat of humid areas.

    It takes a hand, but parasols are also neat for keeping the sun off, with less heat building up under the hat and resulting head sweat.

    Buildings can have ventilated roofs, kind of a hat for the building, absorbing sunlight while having an air gap between it and the main building. And of course awnings.

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