The paper introduces the concept of performance based building and presents a definition of this broad concept, with a focus on the indoor environment. The performance based approach is already known and applied for a longer period but has no general application yet in the indoor environment. Through a practical case, the ventilation system in an operating theatre, the applicability of the concept is verified. In order to proceed, the developed approach has been refined. The stakeholders are used to arrive at the various performance requirements for this case and the performance indicators that can be linked to them. Use of simulation tools in the design phase has specific attention. For one of the requirements, the minimization of the surg...