Definition 1: Building science is the collection and study of technical and scientific knowledge that focuses on the analysis and control of the physical phenomena affecting buildings. It traditionally includes the detailed analysis of building materials and building envelope systems. Building science can be used to improve a home's cost to operate, its durability, comfort and efficiency.
Definition 2: Building science is the study of the interaction between occupants, building components/systems, and the surrounding environment. It focuses on the flows of heat, air, and moisture.