This new AM11, Building performance modelling (BPM), has taken into consideration many of the real issues of simulating buildings and their systems whilst still focusing on compliance with building regulations and quality assurance issues. BPM covers the general concepts of energy and environmental modelling and in particular focuses on: quality assurance procedures, compliance with UK and some international building energy efficiency codes, thermal environment and energy, ventilation, lighting and plant modelling. This Manual has been written by experts in a variety of building design and modelling software, from academia and engineering practices, providing their expert knowledge in the application of these tools to building and system designs.