[rsynnott]

That's census data, and their collection of data is... imperfect. A lot of those 'vacant' dwellings are one of:

* Occupants refused to engage with census taker (I used to have neighbours who did this; you can theoretically be fined for it but I don't think anyone ever has been)

* Home is in the middle of being sold

* Home is uninhabitable.

* Home is in the literal middle of nowhere.

I'd be in favour of measures to free up vacant housing (punitive tax on vacant housing etc; there _is_ a vacant home tax now but it's pretty small), but I wouldn't hold out much hope of getting a really meaningful amount of housing out of it.