Chuck,

I like Terra-Dome homes but be aware that in order to keep the domed ceiling one has to bury utilities under the slab.  Nothing wrong with this except the HVAC lines having to be waterproof will cost more plus one must allow more space under the slab for the larger lines.  More space can be achieved by making the walls taller and then backfilling under the slab.  Another thing to keep in mind is that it is easier to waterproof penetrations through the concrete shell if all of the penetrations are through the slab instead of the walls or roof. 

A flat or sloped concrete roof will have to be thicker and more reinforced since it will not be in compression like the dome.

Contrary to what people may think, an earthsheltered home does not have to feel cave-like.  Either build at the crest of a hill and have daylight on both front and back or build into the hill with shallow modules such as Terra-Dome's 24' or 28' depths.  Shallow depths like this allows more windows on the South side for egress and light.  For your location, regardless of the type of house you build, be sure to minimize the windows on the East and West and size the soffit correctly for the Southern windows.


By the way, A Terra-Dome home is being built in my area.

Posted By twogun544 on 21 Nov 2010 07:48 PM
.  If there are other details that I need to specify or think about let me know. 

Thanks
Chuck

Chris - Thanks for that tip.  How much more do Steel SIPS cost compared to wood?  Is the exterior steel the roof covering or would the steel have to be covered by shingles or metal etc. 

Chuck,

First of all, for your location you really need to face the earth-sheltered home to the South.  If you were in Orlando FL or further South I would recommend that the glass wall face North since cooling would be much more important than heating.

Idealy, the back of the home should be facing True North instead of Magnetic North.  (According to this link http://www.ngdc.noaa.gov/geomagmode...eclination    the declination is 1 degree and 56 minutes W changing by 6 minutes West a year.  This is so close to True North that Magnetic (compass) North is quite acceptable for orienting a home for passive solar.)

The sun being lower in the sky in the winter will come in under the soffit and contribute to the heating of your home.  A horizontal shader (soffit, overhang, etc.) will block the summer sun that is higher in the sky.  However, for this to work well, the horizontal shader has to be sized at least according to the latitude, height the shader is above the window, and height of the window.  For instance, a shader placed too high or not wide enough will not shade the bottom part of the window. 

A sun table like the one used by the School of Architecture at Auburn University allows one to use a scaled model to determine the width of shader necessary to protect the house from the hot summer sun and yet still allow passive solar heating in the winter for latitude and longitude.  Some schools near you may have a sun table.  If not, then my guess for a normal height wall (9' ceiling) for your latitude with a 6' tall window would require a soffit 32 to 36 inches wide.  In my opinion, it is better to have a shader slightly too wide than too narrow.  An overhang or shader too wide for the site will reduce solar gain at the beginning and ending of the heating season.  An overhang too narrow will allow over heatig during this period.

Homes that face South with the narrow overhangs of today really add to the cooling load.  By the way, South facing windows properly shaded from the summer sun should be the type that allows the sun to store heat in insulated thermal mass inside the home.

Here is one link to start your study:  http://www.energysavers.gov/your_ho...opic=10280  Notice the difference in sun angles for summer and winter.

Posted By twogun544 on 22 Nov 2010 10:35 PM

Chris - Thanks for that tip.  How much more do Steel SIPS cost compared to wood?  Is the exterior steel the roof covering or would the steel have to be covered by shingles or metal etc. 

Posted By twogun544 on 23 Nov 2010 07:03 AM
Hmmm I might have to give you a call...Do you distribute to TN?

Wes,

You may be right.  Microclimate overrides macro.  Personal knowledge of an area's weather should be utilized.