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Functional Cupola Info?

2leftfeet's picture

Talking to an older neighbor of mine (80's maybe) we got onto the topic of keeping a house cool without AC or a house fan.

He mentioned that a cupola can let the exiting hot air pull in cool air through the windows, making for a good airflow through the whole house.

Are there any older books or websites that cover this? I have only seen cupolas and weather vanes on barns.

Thanks in advance

(post #77298, reply #1 of 21)

I don't know of any specific books or websites, but I can give you some general information.


I suspect the reason you see fewer coupolas these days is the modern conviction that a house without central air conditioning--especially in a climate like yours--is 'unthinkable'.  Thus, a number of the coupolas one does see today--for instance, on fake 'victorians'--are merely blind-mounted 'screw-down' units which don't ventilate anything.


But a coupola can solve more than one type of ventilation problem, and if it's well designed to match the architectural style of the house, it can be a visual asset as well as a functional one.


First off, a coupola (or series of coupolas) is an excellent way to vent the attic & roof in combination with soffit intake vents. It can protect a much larger exhaust opening than the typical modern ridge vent can provide, and is less subject to blocking by leaves and other debris. You can install a 'Charley Noble' type vent turbine through the roof deck, and build a decorative coupola over that, or you can build a full-square vent trunk and top it with the coupola. (In the latter case, you need to make sure you've taken design steps to ensure wind-blown rain can't enter through the louvers, or it it does, that you have provided adequate catch-and-evaporate basins.)


If you want the coupola to help exhaust hot air from the living spaces as well as the attic, you'll need to provide ceiling vents & trunks up through the attic insulation. In a multi-storey house, if you have a central stairwell, you will benefit from the 'chimney effect' of warm air moving up it from the lower levels to the upper one, through the ceiling vents, and then out through the attic and the coupola. Where you choose to allow the outside air to enter the house has a lot to do with how much natural cooling you can get from this.


Houses with below-ground basements (which remain much cooler during the day) benefit particularly well from this effect, in that you can open the basement windows in the evening and allow the natural circulation to suck in air through the basement where it is cooled further before being drawn up the stairwell, pushing the hot air out ahead of it through the upper storey rooms and the ceiling vents to the attic and coupola.


It is also possible to combine a coupola with a whole-house fan to enable you to move air through the house on those nights when there's little natural movement because the outside temps just won't drop. Modern whole-house fans are much smaller than the 3- and 4-foot diameter monsters I knew in my youth; I've seen twin-fan models that are no bigger than a good-sized ceiling vent.


No matter what kind of coupola you go for, one strong recommendation I would make is to back the louver openings with a sandwich of standard metal bug screening--to keep out wasps etc.--plus heavy-duty ¼"- or ½"-square wire gridding, to keep out rodents (both the flying and the climbing kind).


You don't want bats in your belfry, after all....



Dinosaur


DON'T MISS THE FEST!


 


How now, Mighty Sauron, that thou art not brought
low by this? For thine evil pales before that which
foolish men call Justice....


Dinosaur

How now, Mighty Sauron, that thou art not brought
low by this? For thine evil pales before that which
foolish men call Justice....

(post #77298, reply #5 of 21)

hey Dino,  Nice post.



Parolee # 53804

 

(post #77298, reply #6 of 21)

T'anks. You coupoled anything lately? ;-)>



Dinosaur


DON'T MISS THE FEST!


 


How now, Mighty Sauron, that thou art not brought
low by this? For thine evil pales before that which
foolish men call Justice....


Dinosaur

How now, Mighty Sauron, that thou art not brought
low by this? For thine evil pales before that which
foolish men call Justice....

(post #77298, reply #7 of 21)

Roar! no, but after your post and DanH's it's got me thinkin'!


Parolee # 53804

 

(post #77298, reply #10 of 21)

Thanks! That is great info.

(post #77298, reply #2 of 21)

The grandaddy of them all

http://en.wikipedia.org/wiki/Windcatcher


So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

(post #77298, reply #3 of 21)

  I read awhile back that the size should be 1" long for every foot long the building is.  Or rounding it to the closest size:  22' building could go to 24"of cupola length.


  Bill

(post #77298, reply #4 of 21)

here's one



Mike Smith Rhode Island : Design / Build / Repair / Restore


Edited 4/15/2007 11:34 pm ET by MikeSmith

Mike Smith Rhode Island : Design / Build / Repair / Restore

              www.mfsmithbuilder.com

(post #77298, reply #8 of 21)

Here's one we did that follows the 1" per foot rule, plus a little bit.  Actually I think it's 10% of the length of the garage, 4' for a 40' garage.


Two of the windows are awnings that operate electronically from the second floor.  They have rain sensors so they automatically close if it rains. 


There is a chimney effect that really draws air up and out on all but the most stagnant air days.



 



Edited 4/16/2007 4:58 am ET by woodguy99

 

 

(post #77298, reply #9 of 21)

Now thats a nice looking garage!


Nice work


Doug

(post #77298, reply #11 of 21)

I have one on my house.  It's six feet square and has two electrically opening windows.  The space below is open from floor to cupola and it ventilates well in hot weather.


(post #77298, reply #12 of 21)

Anyone have a photo of one on a ranch house?

George Patterson, Patterson Handyman Service

George Patterson

(post #77298, reply #13 of 21)

If you are serious I will take one of my neighbors house.


Edited 4/16/2007 12:54 pm by dovetail97128


Life is Good

(post #77298, reply #14 of 21)

I'm serious. Our house is a ranch, and I'm having trouble visualizing how one would look on it. You can mail it straight to me, if you think nobody else would be interested.

Thanks,
George Patterson

George Patterson

(post #77298, reply #15 of 21)

george.. if he only emails it to you , then no one else benefits


me, i'd like to see it also


 


Mike Smith Rhode Island : Design / Build / Repair / Restore

Mike Smith Rhode Island : Design / Build / Repair / Restore

              www.mfsmithbuilder.com

(post #77298, reply #16 of 21)

Yeah, I think it fits into the "This I gotta see" category for lots of folks here.


So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

(post #77298, reply #17 of 21)

grpphoto,

It isn't exacly pretty in my opinion, has louvers not glass and is too squat to look good .

How ever it has been on the house since it was built and according to the previous owners worked to ventilate the house and garage (which it is located over). The house and garage had "Trap Doors" in the ceilings that could be lifted to allow the venting to not only vent the attic space but the house itself.

I was told the house originally had two , one over the gargae and one on the main house, the one on the house was removed after storm damage some years ago as I never saw it and have lived here 19 yrs. House is maybe late 60's era.

I do know that what you are proposing is an age old technique for ventilation. They were quite common in the American South. I will see if I can find some info on that later as well.

Edit: I will try for some shots from the street later on.


Edited 4/16/2007 4:38 pm by dovetail97128


Life is Good

(post #77298, reply #18 of 21)

I would think the thing would look halfway appropriate if the house were decorated with a bit of a barn motif -- wide painted cornerboards, etc. Then make the cupola taller and a hair more rustic.


So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

(post #77298, reply #19 of 21)

Yep - I am 3/4 of the way down the barn motif already.

Gotta run some of these ideas past DW. Maybe we can go a few weeks more without heating or AC each year.

(post #77298, reply #20 of 21)

Thanks for the shots. My opinion of the beauty matches yours. I was afraid it would look like that.

George Patterson

George Patterson

(post #77298, reply #21 of 21)

grpphoto,
If it were taller and a but smaller in cross section I would look fine. just a bad design.
Take a look at some old barn photos to develop an idea of scale.

"Poor is not the person who has too little, but the person who craves more."...Seneca


Life is Good