Why are monolithic domes so much more energy efficient than conventional homes? Insulation and mass are the chief components of preventing heat transfer in a home. Concrete is one of the best insulation materials available, and since monolithic domes contain concrete on the interior and exterior, they act as heat batteries that store.
David South, co founder of the Monolithic Dome Institute and Monolithic Constructors, Inc., explains that the average electric bill for a dome house can be as little as half the bill of an equivalently sized house. The reason comes down to insulation.
"When we put heat on one side of a wall, the heat tries to go to the other side," he explains. "We all know that in our homes. When it's hot outside, the outdoor heat tries to make the building hot inside; when it is hot inside and it is cold outside, then the heat tries to go back outside."
Proper insulation will slow or stop this heat transfer, while improper insulation will actually help it along. David continues, "There are several things that stop that heat from moving back and forth: one of them is insulation and the other is mass. If you have a brick house, you have insulation on one side and brick on the outside. The California Energy Commission found that if you put the brick on the inside, it doubles the value of the insulation. Now, the reason for that is that there is a resistance to heat moving through the insulation, but the other function is that of heat storage, and that brick house will store heat. If the brick were on the inside of the insulation, then it would store heat much more efficiently than if it is on the inside of the insulation."
The same rules apply in a monolithic dome, but they function in a different way. "When we build monolithic domes, they have the insulation of the "massy" amount of concrete. So that does a couple of other fun things. One is that the concrete on the inside now becomes a battery that will store huge amounts of heat, so if you are cooking a roast in the middle of July and you've got just a tiny air conditioner, it will drive you right out of the house in a standard house.
"On a dome it will heat the dome shell up just a little bit, and when you quit cooking, the tiny air conditioner starts working to the heat back out. But the heat has been stored in that concrete and it only raised it two or three degrees, so you won't notice it much. But there are 250,000 BTUs stored in there, and that little air conditioner takes them out. So what that does is reduce our energy costs, and energy inputs are also vastly reduced. So it doesn't do anything for hot water or for cooking, but it sure does a huge amount for the building envelope."
In other words, the insulated concrete of the dome acts as a heat battery. It stores heat rather than allowing it to pass freely though the walls. This storage effect keeps the interior temperature of the house leveled out much more smoothly than in a traditional house, and thereby requires a lot less energy to control the temperature.
