Concrete is an important part of nearly every home built in the United States. But above-grade concrete walls traditionally have been looked upon as eccentric or extravagant—domes, underground homes, or coldly modernistic glass and concrete behemoths. The true nature of concrete homes, of course, has always been much more inviting, and now, in unprecedented numbers, the public at large is beginning to accept the idea of concrete homes, thanks in large part to smart new ways that have been developed to build them.
One of the biggest benefits provided by concrete homes is thermal efficiency, which relates to the thermal resistance of a wall and to the air loss from a building. Thermal efficiency more reliably measures energy efficiency of a home than R-value, which measures only the resistance of a wall to heat transfer. One of the main reasons concrete structures perform so much better than wood is that wood structures leak air and can't ever be completely sealed. To measure the thermal efficiency, the front door of a building is sealed around a fan, which creates a certain amount of air pressure inside the building. The measured air loss is used to calculate thermal efficiency. The logic of this is that a wall could have a very high R-value, but it's useless if air can move freely in and out of the building.