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> Sure, mud-huts do have problems with mould

Yeah, mold tends to be the default trade-off when you choose any method of cooling other than AC.

As someone who is allergic to mold, I'd choose an air-conditioned glass-and-steel box any day over a moldy mud hut if they were equally cool. But I do wonder if, given better technology, we could come up with buildings and cities that have the best of both worlds.

Maybe we should look to ancient building materials and methods for new ideas. The Seokguram grotto in Korea, for example, had been dry for over a thousand years until modern "restoration" projects messed up the delicate balance of air and water. Now there are dehumidifiers running 24/7 to keep mold out of the grotto. It's really pathetic. If pre-modern Indian mud huts can reduce the temperature by 10 degrees without electricity, why can't modern science come up with structures that reduce the humidity by 30 percent, for instance?

Beyond energy use, allergies seem also to be a by-product of growing up sanitised & sealed glass-and-steel boxes. Not that it helps people like you and me who already have them, but in the long-run saner construction might help avoid even that.

Yes, I agree that the long-term solution lies somewhere in the middle. Certainly it would be unwise for mass-adoption of mud buildings (not least because they're a LOT of work to maintain), but if architects and builders would become more open to mixing and exploring with traditional techniques and materials (which, lets face it, has been honed over a long period to deal with humidity, heat and uncomfortable climate before electricity) we could probably get much more comfortable and energy efficient buildings and also cities.

An acquaintance of mine, Laurent, works on this in eastern India [1].

1. http://vimeo.com/68119509

"desert coolers + fan, which specifically work by increasing the humidity of the air and then using a fan"

Actually, evaporative coolers significantly reduce the air temperature[1], when used in dry climates.

[1] http://en.wikipedia.org/wiki/Evaporative_cooler#Performance

"At 32 °C (90 °F) and 50% relative humidity, air may be cooled to about 24 °C (75 °F). The dew point for these conditions is 20 °C (68 °F).

"At 40 °C (104 °F) and 15% relative humidity, air may be cooled to nearly 21 °C (70 °F). The dew point for these conditions is 8 °C (46 °F)."

> In Delhi (45 degrees in summer) ...

That's 113 degrees Fahrenheit for American readers. The rest of the world has wisely adopted more rational measurement units. Even Canada, a stone's throw away from the U.S., uses the Metric system.

Both temperature scales are (thankfully) rational. Some physicists have been dabbling in complex temperatures, but thankfully most of us don't need to know anything about them.

Sorry, mathematician joke.

Celsius used two very reproducible tresholds (freezing and boiling points of water), associated them to two very easy to remember values (0 and 100), and defined his scale according to them.

The way Farenheit got to his scale seems really less practical to me, from Wikipedia :

"Fahrenheit proposed his temperature scale in 1724, basing it on three reference points of temperature.[9] In his initial scale (which is not the final Fahrenheit scale), the zero point is determined by placing the thermometer in brine: he used a mixture of ice, water, and ammonium chloride, a salt, at a 1÷1÷1 ratio. This is a frigorific mixture which stabilizes its temperature automatically: that stable temperature was defined as 0 °F (−17.78 °C). The second point, at 32 degrees, was a mixture of ice and water without the ammonium chloride at a 1÷1 ratio. The third point, 96 degrees, was approximately the human body temperature, then called "blood-heat".[12]"

http://en.wikipedia.org/wiki/Rational_number

http://en.wikipedia.org/wiki/Complex_number

It was not a direct response to the "rational" bit.

> two very reproducible tresholds (freezing and boiling points of water)

Reproducible if you happen to be near sea level.

And have the appropriate "water".

Unfortunately in India it's generally Fahrenheit as well, independence from the British didn't remove that piece of the imperial system (in length it's even more confusing where shorter measures feet and inches are preferred while for longer once m and km...).

Indians generally use Fahrenheit only for body temperature... to know if we're running a fever. But off-hand, I'd have no idea what an air temperature of 113 degrees Fahrenheit would feel like. I understand 45C quite easily. Surely you've seen weather reports and forecasts in Indian newspapers and on Indian TV. Did you ever see them use Fahrenheit?

For distances, a person's height is measured in feet and inches, tailors prefer to use inches for their dimensions, plots of land are often measured in feet. But everything else is metric. (Listen to the local farmer speak, in your own vimeo video link.) Speedometer, odometer, fuel, grocery, produce, etc. all use the metric system. To say nothing of my entirely-metric work in engineering.

Yes, you're absolutely right and most Indians seem far more literate in converting between the two than I ever would be. My generalization was way too broad and wrong - thanks for pointing out the specific cases.

It seems like, as with the examples you give, that certain systems are used for certain purposes which was always fascinating to me come from outside. In construction, in rural areas I've found it varying between different parts of the country whether metric or imperial is preferred.