When the outside air or wall temperature is greater than what the thermostat inside is set to, the walls and roof are occasionally sprayed/misted with water. When the water evaporates, it's sprayed again. Non-magical sensors control the cycle to keep each wall optimally damp.
Piping & nozzles can be set under the eaves, around windows/doors, come up from the ground in the near shrubbery, etc. to provide a low esthetics impact.
It could (should) be used in conjunction with automatic window-openers and/or ventilators. And of course using processed graywater and collected rainwater would make it nice and green.
The system is not particularly recommended for exterior wooden structures.-- FlyingToaster, May 28 2010 Nighttime spray cooling http://www.building...D/6089/Default.aspxRelated interesting concept [pashute, Aug 14 2011] Spray roof cooling research http://repository.t...9-31.pdf?sequence=3Found in a snail mail reply from Good Ole Ogle search services circa 1952 [pashute, Aug 14 2011] Solar Shield product - roof cooling with water mist http://www.patterso...om/Solarshield.html=(~) [pashute, Aug 14 2011] Skytherm http://pamovalley.c...1-Presentation1.pdfWhy Solar Shield won't work. (Even uses solar shield's slides, or is it the other way?) [pashute, Aug 14 2011] ... or people with a sense of smell.-- 8th of 7, May 28 2010 Wouldn't this leave a caked on grime that could only be rinsed off with the top-shelf dish detergents?-- swimswim, May 28 2010 Stored rainwater would work well enough, as long as it was stored in a way to prevent growth. This is probably not a good graywater idea.-- MechE, May 28 2010 I'm standing by graywater, but I've stuck the word "processed" into the Summary, which I took for granted and which you would want even if you were just using a small amount of the stuff to flush the toilet with.
[edit: buggerit, the water source isn't the idea, and it seems to be the fishbone cause: removed from post]
"Processed" means not taking from the top(grease, soap scum) or bottom(high concentration of dissolved and suspended solids) of the settling tank, as well as filtering. It's really not going to be much more "dirty" than collected rainwater which has washed off the roof and driveway on it's way, which also gets very basic processing.
Either way, occasionally letting the spray rinse the wall off should take care of deposited solids, and a handful of fungicide in the tank(s) should keep the moss down if that's a problem and it bothers you (I like moss).-- FlyingToaster, May 28 2010 If you design little precipices into the sides of the building, over which the draining water is channeled, you'll eventually create stalactites. *That* would be bunworthy. (Not my bone, btw.)-- swimswim, May 28 2010 The math is complicated to figure how much this would really help. Basically it's swamp cooler for your house. the average summer insolation is around 770watts a square meter (although this heavily depends on your location).
Really though white or light color paint, plus high R value insulation means that only a fraction of that radiant heat ever gets to into your house. Therefore any effeciency gained by lowering the surface of your insulation has to be reduced by the same efficiency of your insulation.
The biggest source of heat would be the movement of air and radiant heat from windows. Building your house in a shady area or covering up windows with wood would reduce the heating requirements much more than spraying poo-water all over it.
you might as well use the grey water to water the lawn or scare away pesky neighborhood kids-- metarinka, May 28 2010 So spray it on the inside of the walls?-- pocmloc, May 28 2010 [metarinka] *very* big difference between grey-water and black-water. This is a replacement for an energy-sucking A/C system on an existing structure, not necessarily a new-build installation.
//math is complicated// actually it's much less complicated than other solutions. You don't have to worry about R-value or anything. The only factors involved are:
- ambient solar insolation - absorption spectra (colour) of the walls while dry vs. while wet - ambient humidity, temperature - ambient wind velocity.
As long as the amount of heat taken off by evaporation is greater than the amount of heat added by the walls changing to a darker colour, you're ahead of the game. Again, the idea is to get the heat off *before* it penetrates into the house.
(Post edited to remove references to water source which really isn't the idea except as an energy-saving, cost-reducing, environmentally friendly usage.)-- FlyingToaster, May 28 2010 And I have a sprinkler that I use to saturate one wall while watering the lawn, doesn't make a purpose-built system "baked".-- FlyingToaster, May 28 2010 Actually I contest that: the fire-sprinkler system relies on saturation of wood as a fire-retardant against sparks, and (I assume) most of the heat-retardant properties are accomplished through carrying the heat away as hot water, not as steam.
Whereas this is evaporative cooling; for concrete structures.
Would be neat to combine the two... you can share my fishbones.
<link> for my own edification please.-- FlyingToaster, May 28 2010 + I do not think it is evaporation that accomplishes the heat transfer, I think it is water flow.
Take 2 bags of the same frozen item - put one in a pan of hot water. Put the other in the same size pan under the tap running cold water. Which one thaws first?
What to do with the heat, though?
I think you run it through a geothermal system.-- Zimmy, May 29 2010 If you keep water flowing down a brick wall, it will eventually come through the brick and you end up with mould inside the house, and I think you'd be using much more energy by constantly shuttling water around.
With an occasional spray, no water would get through to the inside (the surface is sprayed and it evaporates), and the pumping energy is next to nothing (compared to a constantly flowing system).
Also it seems to me that more evaporation would occur with a (constantly renewed) light coating of water (because adjacent brick won't cool down a steam molecule as fast as adjacent water... or ruminations to that effect).-- FlyingToaster, May 29 2010 Baked. Commercial chicken sheds use misting systems inside the sheds to raise humidity on cool the sheds and when it is really hot, like here in Oz, there are sprinklers which spray onto the walls.-- AusCan531, Aug 15 2011 random, halfbakery