At the beginning of the I-HEROS project, this work package focused on the theoretical background of One-Stop-Shops. The three case studies « Hamburger Energielotsen », « Toulose Métropole Rénov » and « ProRetro Hannover » were used to find a practical understanding of how a one-stop-shop works and what it offers for an integrated home renovation.

In 2022, the project analysed which approaches to one-stop shops already exist in Germany and what the development of German one-stop shops could look like. A workshop, an online survey and in-depth interviews with German energy and climate protection agencies showed that one-stop-shops in Germany are particularly popular in urban areas. Their services usually include general information and initial advice, which are mainly addressed to private owners of residential buildings and homeowners’ associations. The desire to further develop the one-stop-shop or set up a new service is very present in Germany. However, challenges such as ongoing cooperation with specialists, long-term financing, support throughout the entire modernisation process and the absence of an efficient monitoring approach need to be overcome.

Based on these results, recommendations were developed for the set up and development of German One-Stop-Shops. They are divided into two cases that are typical throughout Germany: A) Offers for energy modernisation exist separately from each other in a region and B) Offers for energy modernisation have been combined under one roof. Finally, four lessons – « show your service », « be outgoing », « use digital tools » and « connect quality suppliers » – from the Toulouse model are highlighted and highly recommended to be considered in the development of German OSS in order to increase the modernisation rate.