Prof. H.-J. Kretzschmar
- President of the GermanNational Committee of the International Association for the Properties of Water and Steam (IAPWS)
- Member of the Working Group "Thermophysical Properties of Water and Steam" (TPWS) of the IAPWS
- Member of the Working Group "Industrial Requirements and Solutions" (IRS) of the IAPWS
- Voting Member of the Technical Committee TC 1.1 Thermodynamics and Psychrometrics of the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE)
- Member of the German Refrigeration Society (DKV)
- Member of the Association of German Engineers (VDI)
- Member of the Verband Hochschule und Wissenschaft (vhw) (Higher Education and Science Association)