Heat loss from dome house.

[kjocis]

Hello everyone!
I have one serious question, that needs solving. I live in Latvia (close to Finland, Norway etc.) so the weather is quite cold. So I would like to calculate what would be the heat loss from geodesic dome if I built one here. As far as I understand the heat loss can't be calculated in the convential way.
I know how to calculate heat loss from a pipe (and I also know that too little insulation will cool the pipe down due to increased surface area). So I think this will apply to hemispheres too!
Every possible size, resistivity, temperature -everything is avialable, I just need someone to give me some tips on how to advance further with my problem.
I am familiar with PHPP program (if that helps.. but I think it is not designed for spherical calculations!)
Thanks a lot!

 

[BigInch]

Heat loss is a function of the materials Heat Conduction value watts/m2 of surface area and per meter thickness x difference in temperature across the material. All you need to know is that and the surface area of the hemisphere.

From "BigInch's Extremely simple theory of everything."

 

[MiketheEngineer]

I think BIG has it pretty much right!!

 

[concretemasonry]

The dome shape minimizes the exposed area in a cold climate.

One other factor is the materials used. Many materials have great ability to absorb internal heat, which can result in a lower energy requirement . The lighter the structural materials above grade, the lower the ability to retain heat, whilr heavy materials inside the envelope provide more comfort and lower heat requirements and equipment capacities.

Dick

Engineer and international traveler interested in construction techniques, problems and proper design.

 

[bimr]

It will depend on how your residence is constructed. Most of the dome builders are claiming 30% less. Here is a link to resources.

http://www.eric-randall.com/domes/

 

[kjocis]

But isn't heat loss from hemisphere greater than from straught surface? Same as tubes - there are critical insulation at which the heat loss gets even greater (can't remember the formula now..)

 

[bimr]

A dome with the same floor area has approximately 40% less exterior surface area than a box shaped building. That is the basis for claims regarding potential energy savings.

http://www.knauer-inc.com/PDF/Geodesic Dome article THE FUTURIST Magazine.pdf

 

[BigInch]

You must be careful how and what you evaluate in the various alternatives.

Floor area of a hemisphere is almost 2 times that of a box of equal volume, but you could only stand up in the center of the hemisphere.

Surface area of a hemisphere, not counting floor areas, is 77 %that of a box of equal volume.

Total surface area of a heimisphere, counting floor areas, is only slightly less than that of a box of equal volume.

If you lose heat in winter, or gain heat in summer, through the floor, go with a box. If your heat transfer is through walls and ceiling, go with a dome. If your heat transfer is only through the ceiling, go with a box, insulate the ceiling heavily... domes are all ceiling. As heat generated inside tends to be convected upward, a box might present less transfer area through its smaller ceiling.

If you want to stand up in the corners, go with a box, or add a cylinder below the dome and increase the surface area accordingly.

You may want to include construction costs too. Isn't a dome considerably higher?

From "BigInch's Extremely simple theory of everything."

 

[bimr]

Just to be clear, a geodesic dome is not the same as a hemisphere. The geodesic dome has a larger volume and smaller footprint than a hemisphere.

There are a few calculators out there for you.

http://www.desertdomes.com/dome3calc.html

For detailed information, you need to contact one of the firms that specialize in the design and construction of these products.

 

[beej67]

"As heat generated inside tends to be convected upward, a box might present less transfer area through its smaller ceiling."

Well you certainly wouldn't want to call the "more vertical" portions of the dome "ceilings" instead of walls. And the heat might gather in a smaller central part of the "ceiling" of a dome anyway, instead of being spread across an area as wide as the roof of a square.

In the end, this math problem gets quite complex, involving some ugly differential calculus. Alternately, (my preferred solution) you find someone with a geodesic house and ask what their heating bill is.

Then there's this thing, which always intrigued me:

http://www.youtube.com/watch?v=mYOEoRK71_E

Hydrology, Drainage Analysis, Flood Studies, and Complex Stormwater Litigation for Atlanta and the South East -

http://www.campbellcivil.com