Logo umweltfreundlich englisch
Energy certifications for buildings are introduced step-by-step in Germany. These certifications are required when renting or leasing existing residential buildings since July 1st 2008. Those statements of the EnEV have been tightened on January 1st 2009. 
Here you can find appropriate examples for decentralised hot water solution for low-energy houses as a download file. 
With the label “Environmental friendly” CLAGE is indicating heaters that are particularly energy and water saving and therefore more energy efficient.