What will the new policies cost?

There are no clear answers. State officials say consumers and businesses will save money in the long run, as utility bills shrink and the resale value of updated houses and commercial structures increases.

But newly constructed homes will cost more, at least in the foreseeable future, although estimates vary widely. One builder says $50,000 is the premium for a brand-new house with state-of-the-art energy technology. The California Energy Commission says new homes that simply meet next January’s updated building code will cost an extra $2,700 or so. Energy upgrades in existing structures will add to the price of significant renovations.

Advocates for low-income Californians worry about the potential effect on affordability.

“It’s important that sustainability not be defined just in terms of environmental sustainability, but equality and income sustainability,” said Tyson Slocum, director of the energy program at Public Citizen, the non-partisan public interest group. “Cost can’t be a barrier to participate.”

Large commercial property owners say the building code, which is revised every three years, may create a two-tier system for them as the state proceeds toward its goals: It will cost less to do work on buildings that are already somewhat upgraded, and those will probably continue to improve. Older properties that have not been improved regularly may fall further into disrepair, because the initial cost of bringing them to code could be prohibitive.