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solar chimney or cupola  RSS feed

 
Alan Whitaker
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Location: Missouri Ozarks
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I'm building a 2-story 16x32 cabin with a 5/12 roof and a 12x16 cabin with lofts and 9/12 roof.  I want to use passive cooling.  Any experience out there using either solar chimney or cupola?  I was originally going to use an elongated cupola but am finding it difficult to source the type of outward opening windows I had envisioned for the venting.  Now I'm looking at some sort of taller cupola at the center with larger windows that can be opened to act as a sort of solar chimney.  I hope I'm getting across what I want to do.  Any ideas, suggestions etc.?  I'm in a humid and hot (NE TX) climate with winters coldest at about 10 degrees F.
 
Tyler Ludens
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Look for "awning windows."

http://www.integritywindows.com/?page=Casement_And_Awning_Ultrex&gclid=CJmDjtfcj6kCFcZe2godaXEMpg

http://www.andersenwindows.com/servlet/Satellite/awning-windows-for-your-home.htm

I am also hoping to build a cupola on our house, so I'm interested to see what other people suggest.

Here's a page with more info about passive cooling:  http://www.builditsolar.com/Projects/Cooling/passive_cooling.htm
 
Alan Whitaker
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Location: Missouri Ozarks
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I had discovered those windows yesterday but i would prefer something that would open from the top.  I wonder how weather tight those would be upside down?  Of course, the Cupola would have an overhang over the window. 
 
Robert Ray
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I remember seeing solar chimmeny's/cuppola's in some old houses in Savannah. The draft created was incredible.
 
Tyler Ludens
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awhitaker wrote:
I had discovered those windows yesterday but i would prefer something that would open from the top.  I wonder how weather tight those would be upside down?  Of course, the Cupola would have an overhang over the window. 


The kind that open from the top are called "hopper" windows, usually made for basements.

 
Alan Whitaker
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Location: Missouri Ozarks
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Yes, but from what I can tell, the all open to the inside.  That would hamper the flow of air.  I want something to open the outside, hinged at the bottom.  That should give me the straightest flow, I think.
 
Tyler Ludens
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I guess maybe  install the awning window upside down, as you mentioned....

Will you have screens and if so, will you have to remove them to operate the windows?
 
Alan Whitaker
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Location: Missouri Ozarks
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I don't see how I could have screens........unless there is some sort of window that enables that.....?
 
Alan Whitaker
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Location: Missouri Ozarks
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Just checked local Home Depot.  Smallest awning windows are $176 each.  I don't think that is going to happen!
 
Tyler Ludens
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Yeah, it's been a problem for me too, I can barely afford decent windows for the house, forget about using them in any addition like a cupola.  My plan is to buy or make louvers for the cupola,and design it so it can be closed off from the house in the winter.
 
Tyler Ludens
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Robert Ray wrote:
I remember seeing solar chimmeny's/cuppola's in some old houses in Savannah. The draft created was incredible.


I would love to see a photo of the particular design they used, how big it was compared to the rest of the house, etc.
 
Alan Whitaker
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Location: Missouri Ozarks
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I lived in Al and TN for several years.  Most of the old houses that I had any dealing with had had all their passive cooling blocked off, remodeled for A/C and I could not figure most of them out.  I know the 10-12 foot ceilings helped a lot, but to actually get the hot air out, someone had already screwed it up.
 
Alan Whitaker
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Location: Missouri Ozarks
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A link with what I'm trying to accomplish.

http://www.finehomebuilding.com/PDF/Free/021165096.pdf

 
Tyler Ludens
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Yes!    That's what we're trying to do also except we're having to start with our existing house, which is a cube.  We've added screen porches to both floors of the south side, and intend to add extra windows on the east side and a cupola to the roof as time and money allow.  Then our plan is to connect the existing ductwork to the cupola to pull hot air from all the rooms.  The cupola will be closed with a baffle in the winter.  We may also try pulling cold air from under the house through the same central duct system, not sure yet.... 
 
Fred Winsol
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Location: Sierras
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Trying to do passive cooling in a humid environment means you need to move a lot of air.  Many thermal chimneys take advantage of low humidity levels and include some evaporative cooling.  So first you need to find some cold air...
I would suggest looking at an underground 'earth tube' (2-4' diameter culvert) or simple geothermal loops for precooling.  About 3' down you should have about 60F year round - lotsa trenching.  Then use a thermal chimney to move the cool air - no biggie - just make the highest part of your house opening small, and the lowest (coolest) opening bigger - and let 'riding the (psi) gradient' take over. 
Also - some people just stick an 8" dia stovetube out the top part of their roof - paint the top outside black... and when it heats up, listen to the air moving through your house... put cold lower inlet on the opposite side of your house.

There's plenty of stuff out there on these things...  Zion NPS Park Visitor Center has the best example I've seen in the USA on a working thermal chimney. let me know if you need more examples/info.

Fred
 
Robert Ray
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Ludi,
I wish I had taken more pictures when I lived down south.  What I observed was that the chimney was in what I would call the foyer or front entrance. Some of them had actual candle  fixtures that initiated the draw.
 
Mike Dayton
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Location: sw pa zone 5
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The old homes in our area with high cellings used them to help cool in the summer.  They opened the bottom window in the wind side of the house,  and the top window on the other side of the house.  The hot air would rise,  the breeze would come in the bottom window and force the hotter air out the top window on the other side.  Not rocket science,  you just need to remember that Hot air will rise. 
 
Tyler Ludens
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The old farmhouse I lived in as a youngster here in Central Texas had 11 foot ceilings and each doorway had a transom that could open.  The rooms were narrow with many tall windows which could be opened at the top. All parts of the house were only one room wide except a room with a widow porch added on.

I'm planning (or hoping) to add some transoms and other ventilation devices to our crummy modern house eventually....
 
Miles Flansburg
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And as a side note I was wondering if you could install a small wind generator where the hot air exits?
 
Mike Dayton
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Location: sw pa zone 5
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No you can't generate power with a gravity flow like that.  The air would just flow around the blades and not move them.  Wind power requires a force,  and a fairly high wind speed befor it kicks in.  Nice thought,  but no,  it would not work.
 
Thekla McDaniels
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I don't know where you live, but if it is arid, then here is an idea which is in use at Zion National Park visitor center.

They made a chimney type structure, rising out of the center of the building.  At the top, there are some kind of fins at the top, like in a water softener, or the resin sort of plates some swamp coolers use.  The fins at the top function as an evaporative surface. (At Zion, they are gravity flow spring fed, so they do not even pump the water.  The natural breezes move air through the fins, what passes through the fins is cooled, and falls down the "chimney".  Inside, it appears similar to a hearth, but no fire, and the air coming out is COLD, they have to divert most of the airflow because it works too well.  A great innovation.  I've always wanted to build one like it!

Thekla

 
Robert Ray
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Now that sounds interesting, wonder if i could incorporate a cooling tower like that into a greenhouse.
 
                                      
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Yes! That's what we're trying to do too much, except that we should start with our existing house, which is a cube. We have added the screen porches on both floors of the south side, and intends to add additional windows on the east side and a dome on the roof of money and time permits.
 
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