One of the ways to address that is to tax vacant housing units. For example, you could double the property taxes for any house that is vacant for more than x da

One of the ways to address that is to tax vacant housing units. For example, you could double the property taxes for any house that is vacant for more than x days out of a year and the x could be surprisingly high. For multi-unit properties, the property taxes could be multiplied by 1.y where y is the percentage of vacant units or by 2 if all properties are vacant. The revenues from the tax can then go towards a good cause like funding homeless shelters. If there's a need to not only put capacity on the market but fill it, the market will drive rent prices down because it is better to get something for your vacant unit than pay double the property taxes. If that doesn't work and there's still tons of vacant housing stock that is being held off the market to drive up rent, you can always keep raising the vacant housing tax until it works.