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| | STRABAG Property and Facility Services GmbH | Düsseldorf, Köln, Dortmund |
| | Ed. Züblin AG | Frankfurt am Main |
| | IU Internationale Hochschule | Neustadt am Rübenberge, Hannover |
| | HOCHTIEF Infrastructure GmbH/Building | Düsseldorf |
| | Drees & Sommer SE | Stuttgart, München, Frankfurt, Köln Berlin, Leipzig, Hamburg |
| | HOCHTIEF Infrastructure GmbH/Building | Frankfurt am Main |
| | HOCHTIEF Infrastructure GmbH/Building | Erfurt |
| | HOCHTIEF Infrastructure GmbH/Building | Frankfurt am Main |
| | HOCHTIEF Infrastructure GmbH/Building | München |
| | Braunschweiger Baugenossenschaft eG | Braunschweig |
| | ENGIE Refrigeration GmbH | Lindau |
| | HAPEKO Deutschland GmbH | Stollberg/Erzgebirge, Chemnitz, Aue-Bad Schlema |
| | HOCHTIEF Infrastructure GmbH | Frankfurt am Main |
| | IU Internationale Hochschule | München |
| | STRABAG Property and Facility Services GmbH | Nordenham, Varel |