Great question—and there are so many options/examples. A good place to start is NAPHN's policy resource guide107. The City of Vancouver is a star in Passive House policymaking and is seeing pretty amazing uptake of Passive House, thanks to a combination of land use incentives and zoning relaxations for Passive House projects35. One of my favorite success stories is the Passive House policy that Pennsylvania Housing Finance Agency enacted a few years ago to encourage Passive House design and construction in the affordable housing realm60. That policy is being emulated by other states, most successfully in CT and MA at this point. Speaking of Massachusetts, a combination of cash incentives for Passive House units and other policy moves is sparking a surge of multifamily Passive House development63 there.
This barely scratches the surface. Anyone else have favorite policy successes to share?