This study is an extension of the reports “Green Building Rating Systems: Energy Benchmarking Study” and “Decarbonising Hong Kong Buildings: Policy Recommendations and Next Steps” that were published in December 2020. This study has worked to expand the scope of the research from HK to the GBA and examines building policies that offer GSF opportunities. Case studies for policy analysis and decarbonisation pathway forecasts have also been developed for four GBA cities. This study also analyses the challenges and opportunities in decarbonizing the building sector in the GBA and how GSF can accelerate the process.