Building Automation and Control Systems (BACS) are widely recognised as a costeffective means of reducing the energy use of new and existing buildings. The European standard BS EN ISO 52120-1:2022, with its companions ISO 52120-2 and EN ISO 16484-4, formalises this potential by grading building automation into efficiency classes A–D and by defining, function by function, the control capability required at each class. Despite the regulatory importance of this framework, its individual functions are rarely represented explicitly in building energy models. This thesis addresses that gap: it assesses and improves the automation of a non-residential office building against the ISO 52120 framework entirely through dynamic simulation, prioritising the correct representation of each BACS function over energy optimisation for its own sake.