Operation theatre can be optimized using numerical analysis techniques (Memzaradeh and Manning, 2002, Lemaire and Luscuere, xxxx). Computational Fluid Dynamics (CFD) is the common tool to analyze airflow numerically. In order to implement an ultra-clean operation theatre, laminar flow systems, which deliver high air change rates, are necessary. In this study, influences by supply temperature, velocity and internal heat load to indoor climate conditions and air quality have been studied and guidelines for design are raised.