Energy Efficiency and Decarbonization Strategies in Buildings: A Review of Technologies, Policies, and Future Directions

The building sector represents a major frontier in the global response to climate change, accounting for approximately one-third of global energy consumption and a comparable share of energy-related carbon dioxide emissions. This review conducts a PRISMA-ScR–based scoping synthesis of technological, behavioural, and policy pathways to achieve energy efficiency and deep decarbonization in buildings. It systematically examines passive design principles, high-performance envelopes, efficient HVAC and lighting systems, renewable energy integration, building energy modelling, and retrofit strategies. The study also addresses the role of regulatory instruments, energy codes, and certification schemes in accelerating sectoral transformation. The synthesis identifies three cross-cutting drivers of decarbonization: integrated design across building systems, digitalization enabling predictive and adaptive operation, and robust policy frameworks ensuring large-scale implementation. The review concludes that while most technologies required to reach zero-emission buildings are already available, their potential remains underutilized due to fragmented policies, limited retrofit rates, and behavioural barriers. Coordinated implementation across technology, governance, and user engagement is essential to realise a net-zero building sector.