■ What is the rent index and what is it for? The rent index is primarily to help landlords and tenants determine the local comparable rent and to give them legal security - particularly concerning rent increases. It is a so-called qualified rent index, as it has been compiled according to recognized scientific standards and has been accepted by the city as well as by landlords' and tenants' groups. Haus & Grund Bonn/Rhein-Sieg and Bad Godesberg are included in this as is the tenant association Bonn/Rhein-Sieg/Ahr.

■ How was the data for the rent index collected? According to Jochen Wagner, head of the municipal office for land management, the data collection for the new rent index took place between July 2019 and March 2020. Around 50 trained interviewers spoke with tenants on location, and the landlords filled out questionnaires. 10,000 of each group were asked to complete the questionnaires. Among the tenants, 1,650 answered the questionnaires, among the landlords it was 1,800. "The number of responses exceeded our expectations," said Wagner. It was a representative sample of apartments on the free market.

■ What are the parameters for the rent index? According to a resolution of the German Bundestag, the local comparable rents had to be determined on the basis of the past six years. Apartments ranging from 18 to 170 square meters were included. The rents for new buildings occupied from July 1, 2019 onwards were not included.

■ How is the local rent calculated? A base rent is calculated according to the size of the apartment. Other factors include the year of construction, location and features such as flooring and sanitary facilities. They are evaluated according to a point system, which allows a net rent (without utilities) to be determined. Tenants and landlords can calculate the rent with the help of a brochure that the city will now publish. For those who need the information sooner, it is already available online (www.bonn.de/mietspiegel).

The tenant and landlord groups emphasized the importance of the new rent index on Thursday during the presentation. It was adopted by both groups amicably in the end, despite a tough struggle over competing interests. "We have one of the best rent indexes in Germany", Grünberg is convinced, acknowledging that there is still a huge demand for cheaper housing in Bonn. Citing the rising building costs, Münch predicted that the rents would continue to rise in the future.