The 12th ACM International Conference on Systems for Energy-Efficient Buildings, Cities, and Transportation (BuildSys 2025) will host a highly selective, single-track forum for research on systems issues covering all aspects of the built environment, broadly defined. Advances in the effective integration of networked sensors, building controls, and physical infrastructure are transforming our society, allowing the formation of unprecedented built environments and interlocking physical, social, cyber challenges. Moreover, built environments, including buildings and critical urban infrastructure, account for over half of society's energy consumption and are the mainstay of our nation's economy, security and health.