Evaporative cooling for metal buildings

I am about to complete a metal building project. I had shown to me a HVAC study where large industrial sized buildings were cooled by a surface application of plain water, sprayed on with regular PVC lines and regular lawn sprayers. The drainage was collected with gutters, and recirculated. A 25 deg. F drop was possible using this method.
Has anyone here ever used flowing water on a metal building, or any style of structure as a coolant? I'd like to hear of your experiences.
Steve
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The only thing I could think of was crawling on top of shiny metal shed roof. Must have been at least 130 degrees. It's been shown, an inner separated reflective layer can reduce interior heat by a large amount. That's with sunshine.
The roof would still be 105 by your estimation. Probably less. I think that idea sucks.
Greg
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wrote:

Sorry I didn't explain more fully. Temperature reduction was up to 25 degrees from ambient air temperature, not from surface temperature of anything left in the direct sunlight.
HTH
Steve
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I pay $100 per year for "ag water". A fresh supply of cool water will not be a problem. A filter is $100. Sanitizers are dirt cheap, too. I'm just going to have to get it up and running and fine tune from there.
Steve
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Sounds like a no-brainer. Evap cooling works well, and best in dry air. Works in even not so dry air. Copying canvas canteen covers, I used to cool a can of Coca-Cola by wrapping it in a wet rag and sticking it in a blower vent in the boiler room of my ship. Took it down from 100 to about 60 degrees even using humid 90 degree Caribbean air. Powerful air flow though.
--Vic
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I'll defer to the other answers, but here is a consideration: with proper venting you should get some cooling of the roof, but if you water the roof, the interior of the building MAY get cool enough for you, or not. It may be best to use a really large Evap Cooler as that will not only pump in cool air, it will actively circulate the air which may be worth more to you than just a cool roof
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wrote:

Condensation and rusting are a real issue. The reason is to provide an inside welding and work area, and block the wind, so an exchange of air would defeat the cooling idea. With water cooling, the air exchange would not have to be as great. A dedicated welding area would be nice, too, and exhaust less air. It will have two 8x8 doors on each end, so opening them up somewhat will take out the welding smoke. But also the cooler air. This might come down to a combination of both evaporative coolers AND surface watering, or one of the other. Just have to get this monster built and try it out. Summer heat is brutal, and winter winds are just about as bad. Then there's the blowing sand ........
Steve
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Just spitballing, but if you had a roof mounted variable speed fan and put lots of vents around the bottom edge of the building, you should be able to control the wind. If you added pads and water to the vents, you could get the cooling, ventilation and control the winds
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As someone else posted, there was another recent thread on this (maybe for your "roof" spanning the gap between two ocean contianers?)
Any way.... your idea will work, just a mater of getting details right. Good surface coverage would be important.
As HBub mentions, mineral build up could be an issue. At your cost of water, it's not worth recycling but the runoff could be reused as ag water for something so as not to totally waste it.
here is a place
http://en.wikipedia.org/wiki/Rutt's_Hut
that I saw water roof cooling more than 50 years ago. must have work cuz they used it. NJ is not particularly dry so you've go a huge advantage.
Water's advantage is due to ~1000 btu/lb of evaporation energy (8340 btu/gallon) Evaporate 10 gallons per hour and you've got ~7 ton equivalent cooling (of course that's on the outside) but that's still a lot of heat not trying to get into the building.
Forget the naysayers & go for it. If you started with a small section you could do some exerpeiemnts.
Measure (cheap water water meter) the amount of water applied. Collect the water that runs. The difference would be close to the amount evap'd.
Gallons x 8340 btu/ gallon would give oyu evap energy.
12,000 btu / hr ~ 1ton A/C
If you did you run for less than an hour you'd have to extrapolate the "hour's worth of water". Also it would be best to not start the experimental measurements until the water was running for a while and the metal surface was at its "running temp".
All these back of the envelop calcs are not highly accurate but considering the cost of electricity, water & spinkler system parts, they good enough to make the effort worth a try.
Would rust be a concern with the building?
cheers Bob
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And, as any desert rat kid learns when they reach the age of being able to do yard work for their old man are a ROYAL F'N PITA clean up job. You forgot changing those cheesy shredded rope pads, too.
Steve
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