Register all residential real estate transactions with CRA and disclose buyer source of income. Restrict foreign ownership to one residential property per person. Introduce a province wide 2% surtax on residential properties owned by non-residents worth over $1 million. To prove residency, you must submit a T4.  When buying a house, make submission of the buyer's T4 to CRA the realtor's responsibility. Extend the 15% foreigner tax province wide. 

I suspect we would need only a fraction of the NDP's promised 114,000 housing units. Vancouver wouldn't need a vacancy tax.