Building performance simulation (BPS) is the replication of aspects of building performance using a computer-based, mathematical model created on the basis of fundamental physical principles. The general objective of BPS is the quantification and deeper understanding of the building performance in terms of built environment, comfort & health, economy and sustainability aspects. Given the increasing complexity of energy environmental systems in buildings, computer modeling and simulation is emerging as a viable approach to performance assessment. This class aims to give an introduction of the theoretical and operational principles underlying this high-end technology. By a series of oral and self-study lectures as outlined below, the class introduces the concepts, assumptions and limitations of methods, that are currently used to appraise the energy performance of buildings. The subjects are developed from basic principles assuming limited knowledge of computers and application software.