Melbourne is also experiencing a housing crisis similar to Auckland's due to a boom in prices.
So should Melbourne also pull out all the stops to encourage new building? Interestingly, Prosper Australia has been tracking Melbourne's true vacancy rate for over a decade now, publishing their findings in their Speculative Vacancies Report[1].
Before you look at the report, a couple of questions:
1) Do you believe prices are being driven up due to a shortage of homes? (Your comment suggests you do.)
2) If prices were being driven up due to a shortage of homes, would you expect the areas that experience the highest capital gains to have the lowest vacancy rates? (I think most people would agree with this.)
Now, the most interesting finding from the Speculative Vacancies Report for me was that in fact, contrary to what most people would expect, areas with the highest capital gains correlate strongly with those areas that have highest number of empty dwellings.
My own suspicion is that the demand that is driving up prices is not demand for homes, but demand for investments. A speculative boom creates extra demand.
In 2007, the Irish thought they had an undersupply of housing. A short time later it was revealed that they actually had a massive oversupply (once investment/speculative demand was removed). The RBA in Australia is pointing to the same thing in Melbourne (Docklands has a vacancy rate of ~25%+, other sought after areas are approaching 15-20% according to the report mentioned above).
The best thing that Auckland can do to tackle house prices is to address the demand side of the supply and demand equation. There are tonnes of options for doing this but mostly this is an issue caused by easy credit and tax incentives for investing in property. That's the place to solve this problem. It would be folly to encroach on green areas or otherwise spoil our environment in a mad rush to build. If we do that... Ireland here we come!
[1] https://www.prosper.org.au/2015/12/09/speculative-vacancies-...