About AAC's energy efficiency

AAC buildings are highly energy efficient. This efficiency is owed to a combination of high R-value, thermal mass and air-tightness. Numerous studies have shown that the R-value of an integral wall system (on piece) such as AAC need not be as high as that of wood frame construction to perform thermally efficient.

A recent test in the U.S. has shown that an 8 inch AAC wall performs much better than a conventional wood stud wall system with R-30 insulation. In short, AAC alone is an excellent insulator - so good in fact that it is the only product currently available that meets Germany's stringent energy codes without added insulation.

Heating and air-conditioning are major cost factors in the operating expenditures of any type of building. By reducing heating and cooling requirements, lower operating costs with smaller, more efficient HVAC equipment sizes are achieved. AAC has been proven to cut those costs by as much as 50%. Below is a graph noting the energy usage of building types in Phoenix and Denver. Note how much less energy is required for an AAC building versus its most common competitor, CMU.

Thermal Mass and Lag

To demonstrate how the combination of R-value, thermal mass and air-tightness work together, AAC was tested at the Fraunhofer Institute for Architectural Physics in Germany. The test measured surface temperatures of a 10" AAC wall over a 24 hour period. The exterior of the test wall was oriented to receive maximum sun exposure. In addition, the wall’s face was painted black to amplify the sun’s effect and the heat intensity.

While the outside (black side) of the wall ranged from 50°F to over 180°F, the inside wall temperature maintained a comfortable 68°F with only a +/-2°F fluctuation. The following chart shows the result of this test.



In addition to greatly moderating the interior temperature, there is a significant delay (lag time), about eight hours, from the exterior peak temperature to the interior peak temperature. This lag time allows energy consumption to be shifted to off-peak hours, a benefit to power companies - and a major cost savings to the building owner.