Autoclaved aerated concrete (“AAC”), though not much known in the United States, is now one of the many building products being touted as “green” or “environmentally friendly.” This paper briefly examines the advantages and disadvantages of building with AAC, paying specific attention to the aspects of the product that may lend to its designation as a sustainable building material. ACC concrete block showing the cellular pore structure (Shi and Fouad 105) AAC is not a new building material; however it is new to United States of America. It originated from Sweden in the early years of 1920 as a result of a rise in demands of timber supplies; AAC is a lightweight building stone that is manufactured (Shi and Fouad 105). AAC is used in a large number of commercial, industrial, and residential applications. This material has been used in Europe for many decades. Also leading in the use is Middle East followed by South America and Australia. Autoclaved aerated concrete is a precast product manufactured by mixing silica, cement, lime, water, and aluminum powder, and pouring it into a mold. With respect to reinforced AAC products like roof panels, lintels, steel rebar or mesh is also placed in the mold. When added to the concrete, the aluminum powder reacts with the silica, forming millions of microscopic hydrogen bubbles (Shi and Fouad 105). The hydrogen bubbles make the concrete to expand relatively five times its original volume. The hydrogen then evaporates, leaving a tightly closed-cell aerated concrete. The now aerated concrete is cut into blocks or panels which are then steam and pressure-cured in an autoclave. Unlike traditional concrete masonry units (“CMU”), AAC is a solid material system with combined insulative and structural components, and is there in a variety of products that can be used in both load and non-load-bearing applications. Complete load bearing applications, however, are only used in low-rise construction, though large panels are available to take advantage of AAC’s fire proofing, insulative and other benefits on mid and high-rise projects (Craig and Ding 102). Again, the big wall, floor, and roof panels, measuring a number of feet’s long, and feet wide, and in AAC has been used in the United States for approximately 10 years. The United States’ recent embrace of the material is likely due to, the high initial capital expenditures required in setting up domestic AAC manufacturing facilities, and the fact that, unlike many of the countries where AAC is a common product, the vast majority of residential buildings in the United States utilize timber-frame construction (Craig and Ding 102). The rest of the AAC system consists of blocks, which are stacked using thin-set mortar and not traditional cement mortar. The blocks are available in a variety of sizes and types, e.g., standard blocks, typically measuring 24 inches long, 8 inches high, and in thicknesses between 6 and 12 inches; jumbo blocks, which reduce construction time; U-blocks, which have a channel running the length of the block that once filled with concrete, provides structural support as headers and on the top course of each floor and cored blocks, which are used adjacent to corners and openings and have a centered, 4 inch vertical core at one end of the block forming running vertical core through the wall that is then filled with rebar and concrete (Craig and Ding 102). AAC lintels with integrated structural support are also manufactured and are substitutes to using the U-block system for headers. With flexibility and combined structural and insulation components, an AAC entire structure can be made using the one material. Exterior surfaces can be finished with stucco, traditional veneers or siding, while interior walls can be plastered, painted, or left unfinished, in addition to traditional sheetrock finishes. Further, AAC is easy to use and can be cut and manipulated with normal wood-working tools. AAC cut down Additional Material Use and Minimizes Waste and Pollution.