A Foam Dome Home

Enlarge Image Image Gallery Once the outer shell of the foam dome has been cast, doors and windows can easily be set into the walls. PHOTO: MOTHER EARTH NEWS STAFF AND TECTON CORP

Nudged forward by the energy crisis of the 70's (which shows no signs of abating during the 80's), the U.S. construction industry has made some well-meaning — but too frequently haphazard — attempts at building energy-efficient housing. In fact, most new structures tend to be far better insulated than their ten-year-old counterparts, and the weather-stripping business has never been healthier. Also, some of the more progressive contractors have actually begun to orient buildings in such a way that they can catch the sun's heat . . . and it's not at all rare, these days, to see more glass on the south side of a house than on its northern exposure.

However, except for the efforts of a handful of rebellious designers — one of whom has developed a foam dome — the basic configuration of the U.S. home remains unchanged: rectangular . . . with wooden stud construction, some sort of porous siding packed with insulation, and a peaked roof on top. Far too few architects seem willing to accept the inherent faults in such "standard" housing. Let's face it: Attempting to make a conventional structure truly energy-efficient can often be akin to building a dam which is weak by design . . . and then patching it where it leaks.

Heat Loss

Obviously, the root of the problem has been that — until recently — the economics of energy has never forced us to look at our buildings from the point of view of conservation . . . even though the basic guidelines for making the best use of energy have been available to heat engineers for decades. For instance, the heat loss of any structure can be described by the relationship of five factors: surface area, insulation, storage, leakage (called infiltration), and the difference between inside and outside temperatures. Examples of buildings that combat heat loss through each of the five areas have been printed in this magazine since its birth . . . and some of the approaches — such as earth-sheltering — have managed to combine a number of energy-saving methods in a single structure.

But what would happen if an architect were to look at all five of the heat loss factors before designing a building? The form developed as a result of such an analysis definitely wouldn't be the all-American box. For one thing, it's difficult to conceive (within the range of practical construction methods) of a shape that has more surface area per unit of floor space than does a cube. And our ideal heat-holding structure certainly wouldn't be built from any material that requires the addition of both insulation and sealing to be energy-efficient.

Area = 4 π r²

When California-based designer Lloyd Turner decided to take the heat-loss equation to his drafting board, the result was a totally new kind of structure — formed by an innovative blending of known technologies — that just may end up revolutionizing the housing industry.

First of all, to an architect who's attempting to minimize heat-robbing wall and roof area, a rounded structure is nearly irresistible. By using a portion of a sphere (or a paraboloid or an ellipsoid), the surface area for a given floor space can be reduced by as much as 40% from that of a cube. Thus the economy of the dome shape is undeniable ... and — from the standpoint of comfort — a circular room will not have the chilly corners that are frequently found in angular abodes.