What shape building is most energy efficient?

[Loren Booda]

For a given spatial volume and amount of material, what practical structural design conserves temperature best?

 

[Danger]

I would suspect that a sphere would be best, since it gives the highest volume:surface area ratio. One of the reasons that I'm cold all of the time is that I'm so skinny that the outside of my body is bigger than the inside.

 

[Loren Booda]

Remember to include the ground it is build upon, and that it is practical (geodesic sphere/dome?)

 

[skeptic2]

I've heard that building underground is the most energy efficient. Once the surrounding ground is heated to the temperature of the residence, little additional heating or cooling is needed. For the little that is needed, the Earth heats and cools much more slowly than the air so that it provides cooling well into the early part of summer and heat into the early part of winter.

 

[Loren Booda]

Why have underground domiciles proved impractical, judging from the status quo? What increase of energy prices will make them and geothermal energy more commonplace?

 

[Danger]

From anything that I've read, they are extremely practical. Heating bills, even in cold climates such as here, run below $50 a year. Mine are more than that in a month.
The hang-ups might be access (it's best to dig back into a hillside rather than make a big hole and backfill it) and a common human tendency toward claustrophobia. Building codes and zoning bylaws probably have a huge impact in some areas.
I've wanted an underground home ever since I first read about one back in the early 70's. I'm a bit untypical, since I love small confined places and the idea of being underground, however spacious the room might be, makes me comfortable. To this day, I pull my covers tight around me in bed and fantasize that I'm in a little cave while I go to sleep. (Only when I'm alone, though; I'm not that odd.)

 

[Ranger Mike]

Danger..Thats why I am in Key Largo with the gilrs volleyball team...
Ref: the building shape..I agree a sphere is the best design because it dissipated everything ( force, heat) equally in all directions..this is why a rain drop forms a circle when it lands. But on practical matter, it is a bear to build a round building and terrible use of space...humans are used to building square/rectangular things like beds, dressers etc...
from coordinate measureing machine designs (CMM) I have seen over the years.. a triangle design will channel heat to the narrow top of the roof and heat can be piped out or recylced better..flat roofs are worst

 

[Loren Booda]

No wonder the attic fan is one device in my ranch style house (with gable roof) quickest to pay for itself - and it's been going strong for 30 summers.

 

[Artman]

Underground construction is energy efficient, but can cause humidity issues or dangerous gas permeation (such as radon). With ground temperatures hovering around 50 deg F year round 3 feet deep (in my area), condensation can form on inside walls. Proper ventilation, insulation and vapor barrier design is critical.

 

[turbo]

Another consideration is that local codes can mandate multiple exits, windows in bathrooms, and any number of other things that can complicate the building of underground homes. For such reasons, a paper-maker friend of mine built a super-insulated earth-sheltered home. It was heavily bermed but not buried, with all the required external access and architectural elements.

 

[Danger]

I hadn't heard of that, Art, but it's good to know.
I've never thought of going that shallow for my cave, though. The frost-line here is almost a metre. Go down 2 or 3 metres, though, and it stays at about 65°F year-round.
Sorry... I've got to bail on this; W is flying around here like a fart in a frying pan loading all of my stuff into the van, and is insisting that I leave with her right now to off-load it at my place.

 

[Dale]

Why have underground domiciles proved impractical

Mostly mold, radon, flooding, bad views, and soil expansion/shifting.

 

[Danger]

Mostly mold, radon, flooding, bad views, and soil expansion/shifting.

Or none of the above, if it's properly designed.

 

[russ_watters]

You can't design bad views out of a dungeon, but yes, with a proper vapor barrier (which is more difficult than it sounds), properly designed HVAC (residential air conditioners just plain aren't designed for dehumidification-only modes, though) and a heavy-duty foundation, you can eliminate most of the problems.

Flooding...I've got a good story on that. I was working on basement renovation for a university - 50,000 square feet of classrooms - in an old building with a double-wall and drainage in the interstitial space. The building was 80 years old, so the system was in disrepair, pipes had sheared-off between the walls, etc., so the architect decided to build another false wall inside (against the engineer's advice), and not just 4" deep, but 3' deep so that you could walk around the perimeter. They paid a whole lot of money to reduce their usable square footage! But wait, it gets worse. While working on fixing-up the sidewalk outside and changing-out grilles on window wells, we had a heavy rainstorm and the ripped-up sidewalks funneled water into a couple of 8' deep window wells, filling them completely...or at least as completely as they could be filled before breaking the windows. The windows from the inside looked like they were set in 3' deep window sills (looking over the intersticial space) and they acted like funnels, to funnel the water into the newly occupied offices, bypassing that nice new drainage system. After filling the offices up a couple of feet, the office walls disintegrated and sent a few inches of water throughout the basement, destroying all of the fresh drywall. Needless to say, the engineer thought it was hilarious (and I still do!). I believe the damage was something like a quarter million dollars of a 2 million dollar total project.

 

[Danger]

That is too funny, Russ!
I'm no expert in anything (except locks), but I always go by the 'measure twice; cut once' rule. Do it right the first time. Unfortunately, a lot of idiots end up in supervisory positions. I'm not sure whether or not you've heard of the 'Peter Principle'. It states that everyone eventually rises to his own level of incompetence. Someone else, who's name I can't recall, summed it up as the 'cesspool' theory. In any given hierachy, the really big chunks of **** rise to the top.

 

[mheslep]

so the architect decided to build another false wall inside (against the engineer's advice), ...

Architects and engineers, the age old strife I see.

 

[flatmaster]

I would suspect that a sphere would be best, since it gives the highest volume:surface area ratio. One of the reasons that I'm cold all of the time is that I'm so skinny that the outside of my body is bigger than the inside.

once, in a hot bar, I told everyone I was still cool because I had a high surface area to volume ratio. Hot and cool here are used in their temperature contexts of course.

 

[Danger]

Hot and cool here are used in their temperature contexts of course.

Of course...

 

[archis]

Why did architects decide to build another wall? Is false wall a new wall by existing basement wall and there are 3 foot space between them? I didnt understand what is the architects foult that the basement was filled with water.
By the way architects sometimes are very funny people with funny ideas. Theree was a bridge project. One architect offered solution to lower engineer networks space in bridge crosssection. He offered to put electrical wires into a gaspipe so you have 2 in 1.
I thing there must be another tread with funny accidents told.

 

[russ_watters]

Yeah, that's kinda a catch there with that story - the architect isn't totally at fault in that story except insofar as the drainage system that serves the existing intersticial wall also serves the window well. More at fault are the people who tore up the sidewalk without consideration for where runoff would go if it rained. Once the window well filled and broke, no wall drainage system would hold it.

The reasoning for building the false wall was that the existing intersticial drainage system was old and in disrepair. There were a few small visible leaks on the perimeter wall. It was my opinion that these were associated with broken pipes and that they should just fix the individual leaks, fix drains, and patch the wall.

Either way, as it relates to this thread, basements are problematic. It is tough to fix/prevent leaks.

 

[flatmaster]

In an interesting side note, my AC is currently off, but because I live in an appartment, three of my four walls are air conditioned.

 

[ray b]

here is one take on under/ground above/ground teck

http://www.Earth'ship.net/

 

[MurrayMD]

Probably the main energy efficiency parameters for "most practical design" would be wall thickness and insulation type to prevent leakage via conduction and a good tight seal around the envelope to prevent leakage via air transfer. An air-to-air heat exchanger could heat (or cool) the incoming air using the exhaust air to reduce the energy cost for active heating (or cooling). Triple-pane windows help lower energy transfer, as will minimally sized windows on a well-insulated well-sealed house. Solar panels on the roof could also be optimized through roof pitch and orientation.

The hemisphere mentioned in a previous post has been pretty time-honored by the Eskimos for whom snow is the most cost-efficient and energy efficient material. The tax rate is pretty favorable as well.

 

[Loren Booda]

How efficient are the domestic air-to-air heat exchangers nowadays?

 

[MurrayMD]

Good question! I'm not exactly sure what the answer is, but my assumption has been that a single-stage passive exchanger could take the temperature differential to zero by heating the incoming air with the exhaust air until they're the same temperature. Perhaps subsequent stages could repeat this to where by the time the exhaust air is released it's the same temperature as the ambient air.

Even better might be geothermal heating using an underground conduit long enough to heat or cool incoming air to the underground temperature, then air-to-air for additional fine tuning. If that still isn't satisfactory, an underground coolant tank kept at the desired room temperature could could be a final stage for incoming air and maintained at constant temperature by solar energy, whether liquid heating or electrical power. That would make it just a matter of how big the tank needs to be to buffer the fluctuations in the direct availability of solar energy.

 

[MurrayMD]

Update: A company called "Building Performance Equipment, Inc." in New Jersey claims to get over 87% efficiency in their units. Their website is: http://www.lowkwh.com/exchangers.dws