Book excerpt: The book presents the theoretical background of building physics, dealing with the evaluation of physical phenomena related to heat transfer and energy use in buildings, water and water vapour transfer in building structures, daylighting and electric lighting of buildings, sound transmission in building structures and protection against noise, the occurrence and spread of fires in buildings and the thermal response of cities. It contains numerical and computational evaluation methods, numerous computational case studies and examples of experimental analyses. The book demonstrates that the considered physical processes affect the quality of living and working comfort in indoor and outdoor environment.