Thursday, August 5, 2010

Water Cooled Architecture

Evaporative cooling is a remarkably efficient way of cooling down a space, commonly used in desert regions before the invention of air conditioning. The phase-change of the water from liquid to gas absorbed a lot of heat from the building. The gas was condensed outside the building, where it released its heat.
The hottest part of a building in my region is the roof. The bright sun shines upon it, and most roofs are, for reasons that escape me, dark in color and absorb quite a lot of heat. Instead, we make the roof transparent with white underneath, and between the two layers flow a layer of water. When the water reaches the gutter-area, it is siphoned off into a recycling area that condenses it and vents the heat into something else, like a swimming pool, hot tub, or a greenhouse. Air conditioning bills will be reduced, though unless the water is carefully recycled, this would be harsh on the water bills.
A slightly less efficient version of this has a large, leaky hose on the topmost part of the roof, thereby making it rain perpetually at your house. Rain that absorbs 85% of the heat on your roof.

2 comments:

Alex Waller said...

Your electricity bill would probably actually go up, because now you're talking about a constantly running pump with anywhere from 20-50 feet of vertical head, which is a significant amount of boost.
Honestly, if you want to keep your roof cool, there are both clear and opaque IR-reflective coatings based on titanium dioxide that can be applied, though they are susceptible to damage from weather.
Or, if you are exorbitantly wealthy, coat your roof in gold foil...it is one of the best IR reflective materials known!

themadengineer said...

The average city's water pressure for American cities can push water up about 4 stories. Buildings taller than that require a pumping room.
For the southern-California villages in which I imagine implementing this, all you'd need is a pipe.
But yeah, a simple IR-reflective coating is probably way, way, cheaper, and saner.

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