What will homeowners have to do?

Owners of existing homes won’t have to do anything unless they want to. In the case of a major refurbishment in the next few years, an updated state building code, set to take effect Jan. 1, 2017, will dictate any necessary energy-related upgrades.

For the time being, official inspections as such projects proceed will be the state’s main enforcement tool for ensuring increased efficiency.

Meanwhile, some builders are already constructing super-efficient homes, which include upgraded lighting, insulation and heating and cooling systems.