Davis Caves was one of the fairly early popularizers of earth sheltered architecture. I havent followed them lately wbut 10 years ago they were still not so modern in their approach and didn't really have many designs that appealed to me. There are a fair number of earth sheltered homes that I have come across in south central Oklahoma. None I think were Davis. Some are DIY and have had some problems due to lack of knowledge on the part of the owner/builder but there are some I have seen that are very well done.
The "heat it with a candle and cool it with an ice cube" comment is often true with properly executed earth sheltered designs. Blower door test? We don't need no stinking blower door test! Infiltration is not too much of a concern and is limited to a few features that are easy to take care of.
It is extremely important that a truly TIGHT home made with modern materials should have a mechanical ventilation system to avoid the "sick home" syndrome. The only fresh air you get is what you engineer into the space. Radon can be an issue. I put a perforated pipe into the washed septic gravel under my basement slab and took it to the roof. Any positive pressure under the slab will be bled off to the air above the roof. The vapor barrier under the slab will ensure the radon has a much easier time geting to the roof than through the slab. I didn't test for radon, just provided a vent for it. It was less cost and hassle to provide a vent than to get a definitive test. I suppose I could put a baloon over the vent and see if it gets blown up if I run out of real things to do.
My wife was visiting a lady who was living in an earth sheltered home and was told that after the lady's husband died her friends came over for tea and sympathy purposes. During this they happened to look out the front windows and saw a lot of boards and debris in the air. This puzzled them until they investigated and found that some of the outbuildings had been taken by a tornado which passed over the house and they didn't notice till they saw the debris up in the air.They never heard it and if they hadn't lookjed out at just the right time would not have known what happened.
About costs. Concrete costs more to build, usually. Can you recoup the difference in energy efficiency? Some. Earth sheltered has little outside maint. so there is a decent savings there. Fire insurance can be cheaper. Many choices effect the long term cost of ownership. If sales cost is your only or primary concern then cheaper construction is probably going to sell easier, not neccessarily be a better deal for the client, but easier to sell. Manufactured homes with steel frames and temporary trailer tongues can be cheaper by the sq ftto buy but are not typically the cheapest to own over the life of the home.
You can easily get beyond the point of diminishinig returns in pursuing energy efficiency where additional $ spent will take longer to recoup or might never be recouped. This is true too in concrete construction. You need an informed buyer not just anyone with a job and a credit rating to sell a concrete home. For buyers interested in the max glitzy features for the least $, a concrete home would be a hard sell. If termite damage, fire damage/safety, storm damage and such are important issues then concrete at its increased prices starts to look better and better.
You will note that although there are subdivisions entirely made up of concrete homes, the vast majority of comments here do not relate to mass produced and marketed housing. The homes under discussion for the most part are one off custom homes which would most likely be more expensive per sq ft than the typical stick built home even if they were stick built as well. Profit was likely NOT a motivation in any of the homes under discussion. This is not to say that concrete homes can't be built and sold at a profit because the guy who did my ICF has build a lot of ICF houses in the area surrounding Purcell, Oklahoma. Mostly they go unnoticed as they do not patrticularly differ in looks from many other homes, stick built or otherwise.
A good friend of mine has a son in Florida who recently completed a three story block home next to the beach (it looks like a 4 story home.) The first floor is above the garage which is on the ground level. The garage doors, both rollup and passage, are designed to be blown away and allow storm surge to flow through and not harm the structure. The foundation is pier and beam and the piers are DEEP. The block walls are 100% grouted and have a healthy rebar schedule. He is pretty much huricane proof. Storm covers were designed and attachment points were built in for them. No last minute nailing on of plywood. Of course his heating bills are nearly zip in his climate but they do have to run the A/C for humidity control and to cool. He too has very low infiltration in his concrete home and has engineered in proper ventilation.
He spent more per sq ft than he had to but he will not be rebuilding after every storm. How do you assign a $ value to not being displaced and having to go through the hassle of rebuilding or major repairs every so often. What is the peace of mind worth?
I sold my wife on living in tornado alley by promising her that her master bedrooom would be a safe room and she would not have to worry about tornados or be disturbed in the middle of the night by a NOAA weather radio setting off an alarm because of a storm. How do yoiu assign a dollar value to a feature like that when selling a home on spec? Same answer... you have to have an enlightened buyer, even if you are the one to provide the enlightenment.
In my personal situation, I don't expect to ever sell this house as I fully intend to stay here till they cart off my body. So comparative analysis to support a sale is not an issue. There was no loan involved and this joint is payed for so interest on the increase is not an issue.
Pat
