Unfortunately, news regarding tragedies involving crowd evacuations are becoming more and more common. Understanding disasters and crowd emergency evacuation behaviour is essential to define effective evacuation protocols. This paper proposes an agent-based model of egress behaviour consisting of three complementary models: (i) model of people moving in a building in normal circumstances, (ii) policies of egress evacuation, and (iii) social models for integrating models (e.g. affiliation) that explain the social behaviour and help in mass evacuations. The proposed egress model has been evaluated in a university building and the results show how these models can help to better understand egress behaviour and apply this knowledge for improving the design and execution evacuation plans.