There are many people that are willing to rent at the market rate? I would argue that if there is more supply on the market property owners will be forced to rent at lower prices?
For those who do not I would create incentives like raising taxes for empty property.
From the sample of my direct neighborhood I can tell that there are many empty former warehouses that could be turned into housing stock. I don't see the city developing any of those neither.
I tried accessing the German public-service television broadcaster ZDF's website (zdf.de) from outside of Germany, but it seems I'm being blocked. There are national elections happening today in Germany, and I wanted to follow the coverage.
Error:
Access Denied
You don't have permission to access "http://www.zdf.de/" on this server.
Reference #18.5d401002.1740330090.500ca4e4
IMO it is good that Barcelona bought the building. I don't think regulating rent prices and the housing market helps lower rents.
In Poblenou, a district of Barcelona where I live, the city has decided that 50-70% of each property sold has to be purposed for social housing, i.e. limiting the rent to a fourth of the market price and choosing the tenants. Many of the district buildings are abandoned factory halls. I am rennovating one of them to become a house for my family, but am now forced to rent half of it to a poor family. From what I can see from the neighborhood is that there is almost no building activity and that private investments have stopped.