Zweckentfremdungsverbotssatzung für mehr Wohnraum in Karlsruhe – Stellungnahme (2025/0307)

The Stadt Karlsruhe has produced a detailed Stellung‑ und Analyse zur Zweckentfremdungsverbotssatzung für mehr Wohnraum in Karlsruhe. The document, generated automatically by the EHC profile routine, summarises the municipal debate on introducing a ban on the misuse of housing, particularly short‑term rentals and conversion of residential units for commercial use. It reflects the city’s own assessment of housing pressure, vacancy rates and the potential impact of a new ordinance.

Karlsruhe must first establish that it suffers a significant shortage of affordable housing. The city is required to demonstrate high rent‑burden ratios, a widening gap between offer and market rents, and insufficient supply for newcomers. Evidence such as the current Mietbelastungsquote, vacancy statistics and the number of empty buildings is needed before a purpose‑restriction ordinance can be justified.

The ordinance could apply city‑wide or be limited to specific districts. Baden‑Württemberg precedent shows most municipalities adopt a universal approach, but proportionality may allow a geographically restricted version if housing shortage varies across neighbourhoods.

The draft lists four main prohibited practices:

• Use of more than 50 % of a dwelling’s floor area for commercial or professional activities.
• Structural alterations that render the unit unsuitable for residential use.
• Vacancy of a dwelling for longer than six months.
• Short‑term rentals exceeding ten weeks per calendar year. Units already authorised as Ferienwohnungen before the ordinance retain Bestandsschutz (grandfathered protection).

• In 2019, 55‑65 units were identified as potentially misused.
• The 2022 short‑term‑rental study counted 294 active listings (excluding commercial operators).
• A 2024 hotel‑sector analysis recorded 379 active Airbnb units in 2023, now including commercial hosts.
• Official vacancy data from the 2022 census show 5 094 empty apartments (3.2 % vacancy) and a building‑level vacancy of 1.4 %.
• No reliable trend data exist post‑2022, but the administration notes no fundamental change in vacancy since then.

Between 2018 and 2023, 687 apartments were created through conversion, with a net increase of 531 units in the last three years. Only 31 units were lost to de‑conversion. While exact numbers of convertible office buildings are unavailable, the data indicate a modest but notable contribution of office‑to‑housing transformations.

If adopted, the ordinance would allow the city to issue permits, demand registration of short‑term rentals, and impose fines up to €100 000 for violations. Enforcement would require dedicated staff; comparable municipalities allocate one full‑time position per 100 000 inhabitants and often need additional personnel.

Fifteen of the largest Baden‑Württemberg cities have already implemented similar bans. They report mixed outcomes: perceived effectiveness in curbing misuse, high administrative effort, and reliance on sufficient staffing. Quantitative impact on housing supply remains difficult to measure, though many cite a deterrent effect.

• Karlsruhe faces a measurable vacancy rate (3.2 % apartments, 1.4 % buildings) but lacks up‑to‑date data on recent trends.
• Short‑term rentals represent a significant share of potential misuse, with hundreds of active listings identified.
• Conversions from office space have added housing units, suggesting a policy lever for sustainability.
• Effective enforcement will depend on dedicated resources; other cities recommend at least three additional full‑time posts for a city of Karlsruhe’s size.
• The proposed ordinance aligns with broader German efforts to preserve affordable, long‑term housing and limit speculative short‑term rentals, contributing to sustainable urban development across Europe.