co2online gGmbH
Gemeinnuetzige Beratungsgesellschaft
Hochkirchstr. 9
D-10829 Berlin

Tel.: +49 (30) 7676 85-0
Fax: +49 (30) 7676 85-11

For enquiries please use our contact form.

Managing Director:
Dr. Johannes D. Hengstenberg

Claudia Julius

Company registered at the Amtsgericht Berlin-Charlottenburg district court
Commercial Register No.: HRB 912 49
Value added tax identification no.: 27.601/50125

Person responsible for content:
Dr. Johannes D. Hengstenberg

The sole responsibility for the content of this webpage lies with the authors. It does not necessarily reflect the opinion of the European Union. Neither the EASME nor the European Commission are responsible for any use that may be made of the information contained therein.

Expert support:

SEnerCon GmbH
Hochkirchstraße 11
10829 Berlin

Tel.: +49 (30) 36 99 61 00
Fax.: +49 (30) 36 99 61 10
E-Mail: info (at)

Data protection:
Your building details are handled confidentially and are not accessible to unauthorised third parties. Your data is used exclusively for statistical purposes.

If you send an email to any of the service providers listed in the 'advice and action' section, you can decide for yourself whether you wish to include your building details or not.

Exemption from liability:

Due to possible errors during data-input and transmission, no responsibility is taken for any of the information, results or recommendations. The service providers listed are liable under the law and under contract for their own statements and agreements.

As operators of the web pages, and in accordance with the Mediendienste-Staatsvertrag (Government Contract for Media Services) and §8, paragraph 1 of the Teledienstgesetz law, we take responsibility under general law for our own content. The content of the pages has been prepared with great care. However, we cannot accept responsibility for the information being correct, complete, or up-to-date. Our service includes links to external websites, over which we have no influence. Therefore we cannot accept responsibility for the content of these sites; the service providers of these sites are responsible for their own content.