This report is a product of the collaborative research project ‘Validating and Improving the BASIX Assessment Tool for Low-Carbon Dwellings’. Initiated by the Cooperative Research Centre for Low Carbon Living, the University of New South Wales (UNSW) and the New South Wales Government, this project addresses the policy need for post-occupancy evaluation of the BASIX tool by measuring the actual energy consumption of BASIX-compliant dwellings. This report outlines the key findings of this project by highlighting the discrepancies between BASIX estimations and measured energy consumption and provides an in-depth analysis as to why there are discrepancies and what causes them. Project outcomes fill the gap towards achieving a systematic understanding of actual energy performance of BASIXcomplaint dwellings, including the complex and interrelated attributes that contribute to these discrepancies. Findings from this research show that the measured BASIX-compliant dwellings performed well in the overall reduction of greenhouse gas emissions and were close to BASIX estimations, thereby validating the effectiveness of BASIX tool in promoting low carbon dwellings. However, the breakdown of energy consumption measured by this project highlighted discrepancies in energy consumption for space heating and cooling, lighting and plug loads. An analysis of the attributes contributing to these discrepancies between BASIX estimates and actual energy consumption is discussed and recommendations for future improvements are presented in line with: Updating and improving the benchmarks utilised by the NatHERS and BASIX assessment models; Improving construction and building envelope quality control; and Encouraging sustainability awareness and behaviours.