Autoclaved aerated concrete is a type of lightweight concrete. 80 percent of its volume is made up of air, only 20 percent of solid materials. It is this combination of good physical and working properties that makes aerated concrete an interesting material both in terms of technology and cost.External walls, floors and roofs can all be made out of this one material. Supplementary materials, such as are required in multi-layer constructions for thermal and acoustic insulation and for fire resistance, are largely unnecessary, which is a key advantage both in terms of cost and reliable, trouble-free implementation. Other economic benefits include lower costs for transport, assembly and operation. The environmental advantages of aerated concrete are gaining ever more significance.