Monday, 23 July 2007

The Weather in Eden..and airconditioning

Sunday the temperature in Montreal was 25 Celsius or 77 Fahrenheit with 43 per cent relative humidity. Absolutely great weather! The sun shone all day long, but even working in full sunlight wasn’t uncomfortable. Sure, you might sweat at bit, but sweat did just what it is supposed to do—cool you off. Given the moderate humidity, it just evaporated.

Which makes you wonder if this is not the weather to which we are perfectly adapted, the weather of the metaphoric Eden. Certainly the average temperatures in places like Nairobi in Kenya, Kampala in Uganda, and Mbeya in Tanzania--as close as I could find to figures for the East African savannah where we evolved--show average highs in the mid- to high 20s C or high 70s to low 80s F. Some humans migrated from there to places where it was useful to have lighter skin (the better to manufacture Vitamin D in places where the sun didn't shine as much,) but with the exception of a very few populations--the Inuit perhaps--we haven't changed our temperature requirements. In colder regions, we've created artificial climates through clothes and heating systems. Surely it's no coincidence that the "comfort zone" on furnace thermometers is right in that range.

But until the development of air conditioning we weren't able to do much about higher temperatures. Opening windows, sitting in the shade, having someone fan you--that was the extent of making heat more bearable. But all over the world, various air conditioning systems are becoming more common. What this means to the microclimates of our cities--most systems just pump the heat outside, after all--and to our energy consumption are questions that bear much reflection.

Reflection, reflection--that's hard to do when it's hot, though. The forecast is for hotter, more humid weather today, and by late afternoon I may, somewhat guiltily, turn on our air conditioning system...

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