The scope of this thesis is to develop an automated fault detection, diagnostic, and evaluation (AFDDE) framework for building systems. This framework aims to provide a holistic approach to detect, identify and evaluate building faults to the stakeholders to facilitate decision-making. It is adaptable to different building systems as well as flexible to both distributed and centralised implementations. The first component of the framework, fault detection, uses a novel technique called constrained dual Extended Kalman Filter (EKF) to estimate system parameters and then generates symptom descriptions described by probability and severity. The fault diagnostic process uses Dynamic Bayesian Network (DBN) with leaky Noisy-Max model to accommodate probabilistic descriptions of faults and symptoms. The fault evaluation aspect of the system employs existing building performance simulation (BPS) tools to estimate quantitative impacts of the diagnosed faults. A model reduction process called "model-cluster-reduce" is also developed to speed up simulation. Each component of the framework is created with the intention to be generalized to other related areas of research such as model predictive control and BPS optimization. Four case studies of both zone-level and air handling unit (AHU)-level are adopted to demonstrate the functionalities of the proposed AFDDE framework. Overall, the framework shows promising results with a short fault diagnosis time, and low false positive and false negative rates, albeit with the tendency of overestimating fault impacts.In addition to the future work to further expand the AFDDE framework, many fundamental research questions also arise from this thesis.iii Acknowledgements First and foremost, I would like to thank my Ph.D. supervisor, Dr. Liam O'Brien for his guidance and supervision throughout my study. It was a great pleasure to work with him, and I would not have accomplished this work without his mentoring and encouragement.He has aspired me to continue my academic career and pursue my research in building science.