A building HVAC system includes a waterside system and an airside system. The waterside system consumes one or more resources from utility providers to generate a heated and/or chilled fluid. The airside system uses the heated and/or chilled fluid to heat and/or cool a supply airflow provided to the building. A HVAC controller performs an integrated airside/waterside optimization process to simultaneously determine control outputs for both the waterside system and the airside system. The optimization process includes optimizing a predictive cost model that predicts the cost of the resources consumed by the HVAC system, subject to a set of optimization constraints including temperature constraints for the building. The HVAC controller uses the determined control outputs to control the HVAC equipment of the waterside system and the airside system.