Lawmakers and climate activists in Massachusetts are urging state regulators to add a net-zero provision to statewide building codes.

The Massachusetts Climate Action Network, a nonprofit advocacy group, is circulating a letter asking the state’s Board of Building Regulation and Standards to add a net-zero clause to the state’s “stretch” code. Two legislators are pitching the same idea.

The stretch code is a second and more stringent tier of the state building code. While Massachusetts towns and cities aren’t required to adopt the stretch code, 262 of the state’s 351 towns and cities have opted to accept this tier of the code. It requires greater energy efficiency in new buildings than the Massachusetts base code.

The Climate Action Network organized the appearance of some 40 supporters before a May 7 meeting of the building standards board to speak in favor of a net-zero requirement, Energy News Network reported. At the same time, two state legislators have filed a bill that would require the board to adopt a net-zero stretch code. New buildings would have to meet their energy needs with renewable energy sources, both on and off site.

The Network’s letter doesn’t contain any details on the net-zero provision or how it would be phased in. It leaves those details for later, but the group argues that the change would clear the way for Massachusetts communities seeking more aggressive carbon reductions. Legally, communities can’t adopt energy provisions that are any more stringent than the current version of the stretch code. As a result, communities that want to require higher energy efficiency or carbon-natural buildings can’t really move ahead.

“We believe that this reform will help achieve the energy efficiency goals we have as a Commonwealth, and encourage Massachusetts communities to develop better, safer, and more climate-friendly buildings,” the letter reads.

Rebecca Winterich-Knox, an organizer for the Climate Action Network, said in an email that details of the net-zero requirement would be worked out during the regulatory process in conjunction with the state’s Department of Energy Resources.

Not everyone thinks net-zero is a good idea

Paul Eldrenkamp, whose firm Byggmeister specializes in high-performance remodels, told Energy News Network that a net-zero requirement doesn’t necessarily mean buildings will use less energy.

With enough room on the roof or in the back yard, homeowners with big, inefficient houses could meet a net-zero requirement simply by adding more solar panels.

“One of the unintended consequences of net-zero would be that you could build worse buildings and put more [solar] on them,” he said. “I am not a big fan of zero net energy as a building standard.”

Eldrenkamp said he would prefer a building code that requires lower energy consumption, such as the Passive House standard. He also said it’s important to chose building materials carefully to reduce the amount of carbon construction adds to the environment.

“If we’re investing a huge amount of carbon upfront in buildings that are going to have low operating carbon, we’re better off not building at all,” Eldrenkamp said.

In a telephone call, Eldrenkamp said that over time there’s been a convergence of the base and stretch codes in Massachusetts. The International Residential Code and the International Energy Conservation Code are updated every three years, and Massachusetts has followed suit. As a result, the base code has gradually evolved while the stretch code has not been rewritten since it was first enacted as part of the Green Communities Act of 2008.

The question now is what a new stretch code should look like, and a net-zero requirement as emerged as one possibility. But, Eldrenkamp said, the proposal has the effect of lumping renewable energy and building performance standards together when they should be addressed separately.

“I don’t agree with that,” he said. “Intuitively it doesn’t make a lot of sense to me. I want consistently good buildings, and I want the whole region working on decarbonizing the grid. I think those two efforts can best be achieved if we’re not trying to conflate or combine the two.”

Winterich-Knox said the proposed legislation includes a three- to five-year phase in period for the net-zero requirement for communities that have adopted the stretch code. “But to retain Green Community status,” she said, “all municipalities would have to adopt updated versions of the stretch code.” The net-zero provision would apply to all buildings, residential and commercial.

“We believe Passive House standard buildings are the easiest way to get to Net Zero and are proponents for Passive House,” she said. “However, we are focused more [on] making the overall building stock more efficient than on single-family homes.”

Stretch code update is possible this year

Despite the public push by the Climate Action Network, the building regulations board doesn’t actually have a formal proposal to consider, its vice chairman says.

“Nobody as yet has put forward a proposal for discussion about the stretch energy code,” Kerry Dietz, an architect, said in a phone call. “Discussions that have been happening are — basically, at a public hearing, a whole bunch of people were saying to the board that we want a stretch energy code, not what’s in it. There’s no language in front of the board right now.”

The board has an energy advisory committee, with representatives from across the industry, that has just completed writing state amendments to the 2018 IECC. Dietz said that group should be authoring a new stretch code for the state, but so far that’s not happening.

As to the gradual convergence of the stretch and base building codes, Dietz said that as the family of ICC codes have changed on a three-year cycle, so has the stretch code. “The stretch code has always said, ‘Do better than the base code,’ so the benchmark has been moving,” she said. “What many builders are saying is, ‘Well, we can’t go any further.’ That’s the argument from the industry. We can’t get any better than what the 2018 IECC already says to do … It requires us to do so much.”

When is the state likely to revise the stretch code? With any luck, by the end of the year, Dietz said. But for now, she added, “there is nothing in front of the board.”