Deutches Kupfer Institut DKI (German Copper Institute ) Zentralverband des Deutschen Dachdeckerhandwerks (Central Association of German Roofing Contractors) Zentralverband Sanitär Heizung Klima (Central Association of Plumbing, Heating and Air Conditioning) Forum für Klempner, Blechner, Flanschner, Spengler (Forum for Plumbers, Tinsmiths and Sheetmetal Workers)