All around Massachusetts, cities and towns want to go fossil fuel free. Here’s why they can’t.

Solar panel array on the roof of Beverly High School.Joanne Rathe

Across Massachusetts, dozens of cities and towns have said they want to outlaw the use of fossil fuels in newly constructed buildings — considered an easy and effective step toward a carbon-free future.

The state’s new climate legislation aimed to do just that, and required the state to come up with a new building code that would allow cities and towns to move ahead.

The Baker administration promised a draft by fall 2021 but failed to deliver. And now some climate-concerned legislators want the administration to answer for it.

“Each additional day of delay means one day less of public discussion,” said Senator Mike Barrett, who cochairs the Joint Committee on Telecommunications, Utilities and Energy, which is scheduled to discuss the delays — and what to do about them — at a hearing Wednesday. “The clock is ticking down, and Baker’s people know it.”

Representative Jeff Roy, who cochairs the committee with Barrett, said a new building code is “critical to reaching our goals and empowering local municipalities to achieve net-zero by 2050.”

In light of the delay, Wednesday’s hearing will consider legislative action that would allow cities and towns to require new residential and commercial buildings to be “all-electric.”

“On the off chance the stretch energy code either does not emerge soon or emerges but departs from legislative intent, we’re looking at contingency steps the Legislature may want to take,” Barrett and Roy said in a joint statement. “Tomorrow’s hearing is sure to touch on these issues.”

The Baker administration is continuing to work on updating the code and “will issue proposals for these codes for public comment soon,” said Craig Gilvarg, director of communications for the state Executive Office of Energy and Environmental Affairs.

The exact details of the building code won’t be known until the Baker administration releases it and it goes through a public comment period and a series of five public hearings. It is required to be finalized by December of next year. But the intent, as laid out by the climate law passed last year, is that cities and towns could require new buildings and gut rehabilitations would have net-zero emissions. This likely means a future of heat pumps to deliver heat, solar panels to generate energy, and onsite batteries to store what is produced to get to net zero.

But net zero is not zero, and the climate legislation allows for some wiggle room.

Advocates fear the draft from the Baker administration could ultimately allow for buildings to have fossil fuel hook-ups as long as emissions are offset in another way, like the installation of solar panels. While the offsetting is important for the climate, the continued use of fossil fuels in new buildings would ensure that the required infrastructure remains in place into the future, potentially putting the state’s climate targets at risk.

“The thing we’re really waiting for is to make sure that the code is what it needs to be” said Cameron Peterson, director of clean energy for the Metropolitan Area Planning Council. “The definition I would like to see would have a building that has no combustion in it, but depending on how they write the performance standards, it’s possible that fossil fuel hook-ups could be allowed.”

The net-zero building code has been a point of contention from the start. Almost exactly a year ago, Governor Charlie Baker vetoed the climate bill, largely due to his concerns about the net-zero building code and resistance from the realestate and building sector, which feared that a net-zero code could raise costs.

At a news conference at the time, Baker cited lobbying by “folks who are in the building and home construction businesses, who’ve said certain pieces of this bill . . . literally may just stop in its tracks any housing development in the Commonwealth.”

“Those words get my attention,” he said. “We’ve got to build more housing that’s less expensive, not less housing that’s more expensive. And that issue, in particular, really rings true for me, especially as we come out of this terrible period we’ve been in.”

Baker’s veto came after Massachusetts real estate groups spent millions of dollars lobbying against the climate legislation, according to a report by the Institute at Brown for Environment and Society. The report, which analyzed the political influence behind the climate bill, found there were four key groups opposing the bill: utilities, fossil fuel and chemical companies, power generation companies, and real estate firms.

The real estate industry, the report found, “primarily testified and lobbied against efforts to regulate home and real estate energy efficiency.”

Rob Brennan, who chairs the government affairs committee of the Home Builders and Remodelers Association of Massachusetts, said his organization remains concerned that building costs will go up as a result of the net-zero code, which could result in less housing affordability and availability, but he said they are hopeful the administration will find a solution that works for both the housing and climate crises. “The stakes are too high on both fronts,” he said.

Advocates say the concerns about negative impacts from a new building code may be overblown. The state already has an existing stretch energy code that requires things like certain standards for windows and insulation. The code has been adopted by nearly 300 of the state’s 351 municipalities, said Matt Rusteika, who leads the buildings initiative at Acadia Center, a clean energy advocacy organization.

“The building community raised similar concerns around the existing stretch code. ‘It’s going to result in a patchwork of regulations that’s going to be hard to follow, it’s going to increase costs,’ so on and so forth,” he said. “But those concerns have not been born out.”

In late November, the town managers from 30 cities and towns around Massachusetts sent a letter to Energy and Environmental Affairs Secretary Kathleen Theoharides, urging her to ensure that the state’s code is as strong as possible. “For towns and cities to lead the way, the stretch code promulgated by [the Department of Energy Resources] must be strong enough to get the job done,” they wrote. “The municipalities that opt in are eager to be the Commonwealth’s test kitchen. They need bold policies to test.”