Move over Buckminister Fuller.
A Colorado architect-inventor has developed a dome system that soon may eclipse Fuller's now-familiar geodesic dome and even could begin replacing conventional buildings in the coming decade.
The architect is William Milburn, described by his colleagues as a brilliant innovator.
The dome system consists of a layered shell of foam and reinforced concrete sprayed inside an inflated fabric balloon. The advantages of this novel manner of construction, which Milburn calls the stratoform system, are impressive -- energy efficiency and a relatively low construction cost.
The result is a system of construction that seems to have overcome the major limitations of dome design.
Architecturally, there is nothing new about the dome. It dates from before the Green Parthenon. Since the 1930s architects have been experimenting with fabric, concrete and foam domes.
But concrete domes have failed because of the expansion and contraction that result from being half in the sun and half in shadow. Foam domes have lacked permanence and security: They can be broken into with a knife. Geodesic domes are made of a large number of flat, triangular pieces and require considerable labor to build.
In the stratoform domes a two-inch layer of reinforced concrete provides the strength, while four inches of polyurethane on the outside protect from thermal effects and give the dome an insulating value of R-37, the equivalent of 10 inches of cellulose fiber.
Because the dome has 40 percent less surface area than a conventional structure enclosing the same amount of space, the heat loss is even lower than its insulating value would suggest. In a wood-frame house and some geodesics, the 2-by-4s in the walls and ceiling further decrease energy efficiency because they conduct heat more readily than insulation.
Because the stratoform dome is a continuous structure, it does not have this problem. Its thin shell design often makes it two to three times stronger than ordinary buildings, the designer said.
Another energy advantage of the dome is the lack of seams or cracks. This eliminates the problem of infiltration of outside air, which either must be heated or cooled, depending on the season. In fact, these domes are so tight that even in dry climates such as Colorado, dehumidifiers are required, and owners have to be careful to keep vents open and windows cracked to keep the air fresh.
As a result, the dozen or so domes that have been constructed in this matter require 40 to 60 percent as much energy to heat as equivalently sized conventional structures.
According to John Smith of Tecton, the Colorado Springs, Colo., corporation that owns the patent rights and has worked out a number of the practical aspects of the technology, it now is selling domes of 1,500 square feet for $20 per square foot and 4,000-square-foot domes for $15 per square foot.