Roof condensation as water source

[Radiopeg]

I came across this article about a house in Thailand. This one part stumps me for getting more info. Here is the quote: "Some 30 to 40 litres are collected daily on the roof, thanks to a special surface which lowers its temperature at night. Water is then condensed out of the breeze, which is channelled across it by landscaped mounds in the garden." Does anyone have a clue? The builder also makes his cooking gas from yard clippings.

here is full text article http://www.terradaily.com/2003/030928033...axajn.html

[MarkP]

Anyone with roof catchment is already harvesting dew, but to optimize for dew collection you must optimize two characteristics of the roof. The outside surface must emit black body radiation well and the roof should be insulated so that as the roof gives up heat to the dark sky, the roof surface gets colder instead of drawing heat from the living space. Both of these factors contribute to the outer roof surface getting cold and condensing dew.

There has to be a pretty high relative humidity. This won't work in Arizona although the roof will get cold. Also I think that humidity levels are highest within a few feet of the ground so a second story roof would not be optimal.

[Radiopeg]

Thanks, guess it isn't any secret. I just never heard of it being used before.

Life goes on, with you or without you.

[dmbwest]

+++ You get all the diesel in Thailand !

aloha,
pog

[Guest]

There's a ranch up Saddle Road that uses this method and collects quite a bit of water. It is much more low tech though. Just corrugated roofing about ten feet off the ground.

[Bullwinkle]

The technology kind of like the solar stil

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

[dobanion]

Look up "fog collection."

What works really good is like 30% shade cloth, put perpendicular to the wind. Wind blows through it, and it collects tons of dew. You have a gutter under the shade cloth to collect. It works primarily at night when it cools off to the dew point.

[Radiopeg]

Cool. I was wondering about water collection when the rain stops. I guess for Puna a second tank would be the best insurance.

Life goes on, with you or without you.