Superinsulated Geodesic Dome
We're in the process of building our own house, this 46'-8" diameter geodesic dome. The surface is copper-colored Reinke aluminum shakes.
Spring is here. The tulips are in bloom, and the bedroom has turned green.
Steve's studio now has an orange wall, which will be covered in shelves.
The shower has been Marcia's project, from hand-glazing the blue tiles through applying grout sealer. We had to special-order a shower door to get one with clear, untextured glass. It should be in any day now.
Here's a distorted panorama of Marcia's studio. The back walls, which appear to be in the same plane, are actually at right angles.
Final ground floor layout:
Here's a page about the earlier stages of the
So why a superinsulated dome? I've always loved the looks of domes and
the feel of their interior space. The fact that they're stronger and offer less wind resistance
was also a factor because we're in tornado country. Domes typically survive tornados
and hurricanes that destroy an area's rectangular houses.
As far as energy efficiency, a sphere encloses maximum volume with minimum surface,
so for a given volume of space a dome will have less surface area through which to lose heat.
Some of the dome's volume may be inaccessible, but it's still like getting beautiful
high ceilings with no energy cost penalty.
We used the
Add enough insulation to a well-sealed house and you eventually reach a point where
ambient heat sources are enough to keep the place warm. That's the basic idea behind superinsulation.
Houses are full of
electric lights, appliances, computers, VCRs, people, pets -- all of them throwing off heat.
South windows let in warmth from the sun. In a conventional house, all these sources are
trivial compared to how much heat is pouring out the walls. A superinsulated house
loses heat so slowly that these incidental heat sources are enough to keep the place
comfortable most of the winter. When they fall short, one small electric
heater can make up the difference.
When building the superinsulated house, the cost of the extra insulation and airtightness
can be at least partially offset by the savings from not having to include a furnace
or a complex heat distribution system. Because the house is so well
sealed, a heat-recovery ventilator is a good idea. That's a device which uses heat
from the outgoing stale air to warm up the incoming fresh air. The most efficient models
also capture latent heat from humidity and are known as energy-recovery ventilators.
Deciding what type of insulation to use was tough. I settled on urethane foam because it has
around twice the
Here's an interesting
comparison of fiberglass and urethane
from Monolithic Dome Institute. This article convinced me to spend the extra money
on polyurethane foam, though I definitely question their conclusion that 3" to 5" of urethane
is the most anyone would ever need. Monolithic domes generally still require conventional
heating systems, and with more insulation I believe that wouldn't be the case.
Foam hasn't always been the most environmentally-friendly building material,
but that's starting to change. It no longer uses gases that are damaging to the ozone layer.
Earth Foam, the brand we used, is made largely from castor beans. In any case, I'm comfortable
using a few petroleum-based materials in the construction phase if it means having a house
that more or less stays warm on its own after that. Many otherwise-green buildings
still consume conventional amounts of natural gas every winter, year after year, forever.
Which house is greener over the long haul? I'd say it's the one with all that foam in
the walls and no chimney.
"Call it the groove factor, call it the hipness quotient... there is a timeless,
future-primitive chic to the geodesic that few houses offer. The dome concept appears to be erected
on the improbable intersection of hippie culture and the space age."
-- Matt Jones, Independent Online