Vienna built a bunch of social housing under social-democratic rule to decrease rents, and unlike most other cities, they opened it to a relatively wide income bracket. The value added, if you want to call it that, is _less_ money is spent on rents in the city. Supposedly, a majority of units in Vienna still falls under social-housing restrictions, though I don't have the time to dig deeper now and so I can't tell you what proportion is directly owned by a public enterprise and what proportion is housing co-ops (a somewhat popular model in Europe).