Subject: Re: Passive Home Cooling

From: [email-masked] (JFM)
Date: Fri, 09 Aug 1996 20:17:33 GMT

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____                  _____________  (ground level)
|//|                  |//|
|//|~~~~~~~~~~~~~~~~~~|//| <--------- Insulation
|//|____(water)_______|//|
/////////////////////////|

Here is text from  _Natural_Solar_Architecture_  by David Wright:

"A dew pond is an ancient device once used in southern England for
collecting cool water. These shallow ponds of water, insulated from
the earth, radiated heat from their surface to the night sky. The
concept of these ponds could be updated, using modern materials
instead of the clay, straw, and flint which were traditionally used.

"As heat is radiated from the water surface, some evaporation occurs
until the temperature drops to the dew point of the night air.
Continued cooling causes water to condense out of the immediate
atmosphere into the pond. The process continues as long as there is a
net radiation heat loss from the pond. Night dew can replace moisture
lost by evaporation; this condensing of water into the pond adds some
heat to its thermal mass. With an insulated cover, during summer days
heat gain and evaporation is reduced.

"A dew pond radiating to deep space can lose enough heat energy to
drop its temperature to freezing if the moisture content of the
surrounding air is low enough. This idea could be adapted to use in
structures and provide cooling for buildings in many climates."

Clearly, the climate in southern England, at a latitude roughly equal
to Connecticut and surrounded by water, particularly with respect to
humididy, would not be much different than that of much of the US.

Interesting, no?

JFM

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From: [email-masked] (JFM)
Date: Fri, 09 Aug 1996 20:17:33 GMT

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Interesting, no?

JFM