Aerated concrete blocks have been used in Europe for more than 50 years. Like typical concrete blocks, aerated concrete is strong, fire resistant and good sound insulation. However, aerated concrete is also lightweight and energy efficient. Aerated concrete was brought to the U.S. about a year ago by Hebel Southeast, a German company with offices in Atlanta, Georgia.

The energy efficiency of aerated concrete blocks compares well with other concrete blocks for three reasons. First, the insulating value of a standard 8-in. block is R-11, considerably more than typical block. Second, the blocks thermal mass can moderate temperature swings. This is most useful in climates with high cooling needs. Third, the block wall is inherently airtight. Blower door results show an air leakage rate of 2.6 air changes per hour at 50 pascals.

The company says material is cost competitive with wood framing. In addition to being lightweight, the blocks can be cut with a handsaw. Channels for pipes and wires are cut with an electric router. All these features add up to a product that's easy to use and energy efficient.

Note: Hebel is now sold in the U.S. by Babb International. Please search the Oikos Product Directory for sources of ACC blocks.