We often focus on the big drivers of housing costs. But, behind those, there are many other smaller drivers — like the way your property is assessed.

This past year, housing non-profits had their properties assessed as though, any moment, their buildings could be torn down and replaced with market-condo towers.

That could never happen, for the most part, because those housing groups have legal agreements to provide units at below-market costs.

For once, however, everyone scrambled to come up with a solution that would see their assessments reduced to reflect the fact that 1. they are not going to re-develop to luxury condos, ever and 2. they are renting for below-market rates.

A good win, as I note in my story.