The efficiency of energy usage in buildings has become a crucial focus in research and practical applications as the global energy demand continues to escalate. Buildings are responsible for approximately 40% of worldwide energy consumption and significantly contribute to carbon emissions. This paper examines recent advancements in energy- efficient technologies, materials, and methodologies utilized in both residential and commercial buildings. Key focus areas include passive building design, advanced insulation materials, energy-efficient HVAC systems, innovative building technologies, and incorporating renewable energy sources. The review of energy efficiency in buildings underscores promising areas for future research, such as smart grid integration, AI-driven energy management, and the potential development of zero-energy buildings (ZEB).