Annotation: The information and control system of smart building is considered as a set of subsystems including building automation system (BAS), communication and controllers considering their failure rates. BAS security and system availability during life cycle are assessed using IMECA, FMECA, Markov’s model. IMECA is applied to investigate any intrusions into BAS by analyze of vulnerabilities and effects of attacks using criticality matrix. FMECA is applied to assess criticality of BAS hardware failures. Markov’s model is used to calculate BAS availability considering the possibility of recovery and different kinds of the faults.