Builders and architects are pushing lawmakers to strike a section of the much-touted energy bill that they say will increase construction costs, cause confusion in the industry and hurt economic development.

A provision in the legislation would enable communities to establish and enforce their own building codes on both new and existing buildings, they say. Currently, all structures are constructed under one mandatory uniform building code.

“If [contractors and designers] had to comply with 351 cities’ and towns’ building codes, there would be chaos,” said Paul Moriarty, a Norwell attorney and code consultant. “There’s no way they’d be able to do it. It would stop them from doing work up here.”

Separate versions of the legislation were passed by the House and Senate, and a conference committee is hashing out the differences. The legislation is intended to reduce energy consumption and promote alternative energy sources.

Those in the construction industry oppose a section in the Senate version that would enable cities and towns to set up green communities. As part of that, towns would be able to create and impose building codes on new and existing properties that “will assist green communities in achieving their community-based goals and objectives.”

“The whole point of the state building code is there’s one book that we all go to that dictates everything from how high a doorknob should be to Â… how to build exterior walls,” said John Nunnari, who works at HMFH Architects in Cambridge.

Nunnari said under Massachusetts law, communities already are allowed to petition the state Building Board of Regulations and Standards, or BBRS, if they want to adopt a more restrictive regulation that isn’t in the building code. “If they wanted every new building to be built with grass on top of the roof, then the city or town could go to the board and make the case that it’s a regulation they want in their town,” he said.

If there is no consistency in building standards from one town to another, the cost of construction and design services will rise, opponents argue.

Nunnari, a member of the Boston Society of Architects’ Legislative Affairs Committee, worries that it could discourage development because developers would find it easier to build in states with consistent building regulations.

“We don’t want to make Massachusetts unique in the sense that we have 351 building codes. We want one building code, and that code should be the same here as it is in California or Arizona,” he said.

If each town could create their own building standards, “builders wouldn’t know how to prepare for that,” said Norwell Building Inspector Tim Fitzgerald.

“We want one unified code,” added Fitzgerald, who is president of the Southeastern Massachusetts Building Officials Association.

A ‘Fragmented’ System

The legislation could set the state back 35 years to a time when the state had a costly and outdated building regulatory system, according to critics. It wasn’t until 1972 that a state building code commission, which eventually became known as the BBRS, was established. The first statewide code was adopted in 1975.

“The consequences of returning to a fragmented building regulatory system such as existed prior to 1972 could be devastating to the commonwealth and include confusion in the design and construction industry, added time and delay in the design and construction of buildings, increased cost of construction to businesses and potential homebuyers, uneven code enforcement, a weakening of public safety standards, and arbitrary approval or denial of the use of certain materials or construction methods,” the Massachusetts Building Code Alliance wrote in a letter to legislators.

The alliance is a coalition of contractors, designers and material suppliers that includes the Massachusetts Society of Professional Engineers, Home Builders Association of Massachusetts and Boston Society of Architects.

The commissioner of the Massachusetts Department of Public Safety Thomas G. Gatzunis also has concerns.

Gatzunis sent a letter to Sen. Stephen C. Panagiotakis, chairman of the Senate Ways and Means Committee, noting that under state law only people who are code-trained and certified can enforce the building code. The section at issue would empower green communities to determine who enforces the local code, according to Gatzunis.

“There are no requirements or other qualifiers and therefore regulators who are not properly trained may be authorized to enforce the code. This poses a significant public safety issue,” he wrote in the letter.

Designers and contractors also are troubled by another section that would require the BBRS to fully adopt the latest International Energy Conservation Code. They say the section legislates the adoption of a particular building code and appears to prohibit the BBRS from making any changes.

“Essentially, by doing that, you’re stuck with the International Energy Conservation Code and you’re not able to amend it in any meaningful way,” Nunnari said. “You shouldn’t be legislating the building code regulations.’

Nunnari said regulations are easier to change, and anyone can petition the board for regulatory change but it must be science-based. “The legislative process isn’t always based on strong science. It’s often based on public opinion,” he said.