A Comparative Life Cycle Assessment of Autoclaved Aerated Concrete Blocks as a Sustainable Alternative for Residential Construction in Australia

The building and construction sector is a major contributor to global energy consumption and greenhouse gas emissions, underscoring the need for material-level strategies to minimise environmental impacts throughout the building life cycle. This study presents a life cycle assessment (LCA) of a prototypical two-storey brick veneer residence in Sydney, Australia, using eToolLCD software V4.7 to V5.40. Two environmental impact categories were evaluated, namely embodied energy (EE) and global warming potential (GWP). Over the 55-year reference service life, the case study residence generated a total EE of 1,191,015 MJ NCV and a total GWP of 82,678 kg CO2 eq, equivalent to 98.18 MJ NCV/m2 gross floor area (GFA)/year and 6.816 kg CO2 eq/m2 GFA/year, respectively. The products stage dominated both environmental impact indicators, accounting for 99.35% of total EE and 67.85% of total GWP. Among the building elements, the wall structure was identified as one of the primary contributors, accounting for 29.54% of total EE and 31.12% of total GWP. To identify sustainable alternatives, two international case studies employing AAC block walls were examined, namely, the Wilson Residence in Florida, United States, and the IPCW Residence in Surabaya, Indonesia. A controlled wall area-based comparative environmental analysis of three wall construction systems (brick veneer, AAC blocks, and hollow concrete blocks) demonstrated that the AAC block wall system exhibited the lowest EE (9.752 MJ NCV/m2 GFA/year) and GWP (1.2615 kg CO2 eq/m2 GFA/year), representing approximately a 44.1% reduction in EE and 23.9% in GWP compared to the brick veneer wall system. This wall-system finding was corroborated by a supplementary comparative analysis using environmental product declaration (EPD) data for generic AAC blocks and clay brick. Under the specific assumptions, system boundaries, and impact categories examined, AAC block walls demonstrated lower EE and GWP than brick veneer walls in this Sydney case study residence, indicating their potential as a lower-impact wall material for Australian residential construction. Compared to brick veneer walls, AAC block walls may reduce both EE and GWP while maintaining high thermal performance, durability, and construction efficiency, thereby contributing to more sustainable housing and support Australia’s transition towards net-zero emissions.