Sprinkler on the roof: WATER AS AN ECOLOGICALLY SOUND HOME COOLING AGENT

[MsDoodahs]

Thought some of you might be interested in this idea - especially we Texans.

http://www.doctajstutoring.com/webdoc22.htm

 

[Kotin]

Interesting... Thanks for posting!

 

[noxagol]

Interesting indeed.

 

[Original_Intent]

Very cool! (I made a funny!)

 

[tmosley]

Awesome! I was trying to think of a way to sustainably cool one of my outbuildings, and this should do the trick handily. I bet I can even plant garden beds around it to catch the runoff.

I might even use it on my main house.

 

[Ninja Homer]

I'm in Minnesota, so it probably isn't as big a deal for me as it is for you Texans, but we do have some pretty hot summer days here. I was considering installing one of those patio misters this year.

http://www.amazon.com/Evaporative-Mist-Cooling-System-Breeze/dp/B000JMN9IE/

The super fine mist makes the evaporation a lot more efficient, but I'm not sure how well it'd work on a roof. On a calm day it would probably work as well as a sprinkler, but on a windy day, a lot of the mist would just blow away.

 

[dannno]

Wow, that's amazing.

 

[Acala]

Interesting

Here in Tucson, evaporative (what the article calls "swamp") cooling is very common. I have it in my house. I love it because not only is it much cheaper than ac, but you must leave windows open to get the proper flow. So it is constantly blowing fresh, cool air through the open house.

Unfortunately, it doesn't work well when the ambient humidity rises. It loses efficiency and makes the house very humid. That happens here during the summer monsoon in July and August. I switch over to AC when the monsoon arrives.

However, the idea of spraying water on the roof is interesting both as an adjunct to the use of the evap coolers AND to the ac. I'll be trying it this weekend.

 

[tmosley]

Here in Tucson, evaporative (what the article calls "swamp") cooling is very common. I have it in my house. I love it because not only is it much cheaper than ac, but you must leave windows open to get the proper flow. So it is constantly blowing fresh, cool air through the open house.

Unfortunately, it doesn't work well when the ambient humidity rises. It loses efficiency and makes the house very humid. That happens here during the summer monsoon in July and August. I switch over to AC when the monsoon arrives.

However, the idea of spraying water on the roof is interesting both as an adjunct to the use of the evap coolers AND to the ac. I'll be trying it this weekend.

The neat part about putting it on the roof is that the humidity doesn't matter so long as there is direct sun. The UV will vaporize the water no matter what the level of humidity (up until they get absorbed by clouds before hitting your roof).

 

[dannno]

You can also recycle the water and use it to water a vegetable garden.

 

[Acala]

Yup

The neat part about putting it on the roof is that the humidity doesn't matter so long as there is direct sun. The UV will vaporize the water no matter what the level of humidity (up until they get absorbed by clouds before hitting your roof).

Exactly. Which is why it will work as an adjunct to the ac during the monsoon.

 

[Acala]

Yup

You can also recycle the water and use it to water a vegetable garden.

Yes. I will apply it on the area of the roof that drains into my cisterns! Although in theory you should only spray what will totally evaporate. If you have much runoff, you need to turn down the volume.

 

[MsDoodahs]

Remember that the runoff can be extremely HOT!

 

[Old Ducker]

Water flowing turbulently in thin film produces extremely efficient heat transfer, especially if there is a phase change (vaporization). On the other hand the lowering of attic temperature will only have a modest effect on internal temperatures depending on the structure. Plus there would be a big spike in water use if lots of ppl did this.

 

[Zulator]

What a great idea! I doubt we have to worry about too many people doing this, mist don't read teh Ron Paul forums!

 

[Elwar]

At first I was thinking that this was a crazy idea...(the heat on your roof is already escaping upwards through the air, why trap it and run it down to the ground?). But it does make sense, water transfers heat much better than air, and it looks like his tests turned out well.

I could set up a rainwater tank to capture rainwater and pump it up to the roof to wet it down and then have the resulting water flow back into my rainwater tank...

Also, check out this cooling system:
http://mb-soft.com/solar/saving.html
It's a series of pipes dug 6 feet down to where the temperature stays constant, the air from your home goes into the pipe, gets cooled off then goes into your home. I was thinking that since I live on a canal I might be able to put the pipes just under the bottom of the canal and the heat would dissipate a lot quicker.

 

[catdd]

I wonder how it would work in a very humid environment like Tn?

 

[Deborah K]

Love this! Thanks Ms.Doodahs!

 

[JK/SEA]

You can also recycle the water and use it to water a vegetable garden.

Depends on what material your roof is made of. Composition roofing is basically asphalt. Not sure you'd want that runoff of leached out asphalt in your veggies.

 

[free1]

Put your hand up on your ceiling on a hot day. If it's hot then you need to spend your efforts insulating your attic.

You can also get a "gable vent fan", it will blow hot air out and suck cooler in from the other vent.

Windows in the west are also a problem, try to do something about those.

Swamp coolers do the water thing for you.