Enact a Land Value Tax. In a squeezed market like Vancouver most of the value in houses is the plot of land underneath them, not the "bricks & mortar". By taxing the value of the land rather than the property on top of it you won't penalize people for renovating or knocking down an old building and replacing it with a newer one. Hopefully the tax is high enough to put off speculators and bring prices to a more reasonable level (because massive swings in land value of 20% per year will increase the tax burden).