Office buildings in particular have high energy consumption followed by high operational costs and emissions. In addition, regulated air exchange is becoming increasingly necessary due to the COVID-19 pandemic. While current building management systems work with primitive rules and basic scheduling functions, Demand-Side Management (DSM) allows smart solutions by using Internet of Things (IoT) devices. Artificial Intelligence (AI) planning can be used to plan the energy demand of buildings intelligently. It provides powerful techniques for the automated and dynamic selection and organization of actions that, when carried out, achieve a specific goal. In this thesis a Demand-Side Management system with AI planning has been developed, which adjusts the temperature and CO2 values of an office room to a comfortable and healthy level. The company SPIRIT/21 equipped 12 office rooms with sensors and wants to test the developed system with real data gathered by them. The system, running with the OPTIC planner, uses the data to calculate an efficient solution, resulting in a comfortable indoor climate, regular air exchange, increased energy efficiency and in lower operating costs.