The Hermann Rietschel Institute (HRI), Department of Building Energy Systems at TU Berlin, is the world's oldest university specialty in the field of heating and ventilation technology and has significantly influenced this area throughout its more than 130-year history. Today, the HRI is one of the leading teaching and research institutions in its field in the German-speaking world.

Since 2011, Prof. Dr.-Ing. Martin Kriegel has been heading the department, with a focus on contamination control in cleanrooms and operating theaters, aiming to improve energy efficiency in such pure environments. To this end, research projects are developed at the department, and the knowledge is passed on to future engineers through teaching activities.

For experimental investigations, the HRI has a highly modular research laboratory consisting of two cleanrooms with associated airlocks. The configuration covers approximately 90% of practical cases of cleanrooms — making this research cleanroom unique in Germany.