New restrictions on the use of natural gas to power some large buildings in Denver took effect in January, but it remains unclear when more rules about gas in single-family homes might be considered again.

During his campaign, Mayor Mike Johnston promised to ban gas hookups in new residential buildings — one of the key differences between his and his opponent’s climate platforms. If fulfilled, the new rule would mean all new homes would be powered solely by electricity, with no natural gas for heating, hot water or appliances — including for gas kitchen ovens and stoves.

The timeline for when such a policy might be pursued remains unclear.

“The city and county of Denver is committed to reducing planet-warming emissions from buildings and homes,” Katrina Managan, director of buildings and homes in the city’s Office of Climate Action, Sustainability and Resiliency, said when asked about the status of a gas ban for new single-family homes.

In the meantime, the city spent months preparing for the Jan. 1 implementation of new rules for large multifamily and commercial buildings. Most new buildings in those categories must have water and heating systems that are partially electric — part of a series of rules that will come into effect in coming years to further limit gas.

According to the city’s climate office, buildings and homes generate nearly two-thirds of the greenhouse gases in Denver — emissions that trap heat in the atmosphere and lead to climate warming. About 49% of those gases come from commercial buildings and multifamily residential structures, and another 15% come from single-family homes, Managan said.

Moving buildings away from gas is an important way to reduce emissions and better residents’ lives, she said.

“These are the places we work and live and spend 90% of our time,” Managan said.

The Denver City Council in December 2022 declined to pursue a ban on gas in new residential buildings as part of the city’s building code. The council instead asked for more information before making such a change.

The thinking at the time was that if the council could hammer out the more complicated electrification of commercial and multifamily buildings, then the more simple residential code would follow easily, said Christine Brinker, senior buildings policy manager at Southwest Energy Efficiency Project, who helped create Denver’s new code.

“Then they basically ran out of time,” she said.

Since then, six of the city’s 13 council members have left office and Denver elected a new mayor. The Southwest Energy Efficiency Project has had encouraging conversations with new and returning council members and the new administration, Brinker said. Though there hasn’t been much action on new climate policies from city leaders since the spring election, Brinker chalked that up to a lack of time and competing priorities — not a lack of will.

“I know it’s a really contentious and complicated issue,” Brinker said of electrification. “I know it’s not 100% perfect, but I also know that what we’re doing now isn’t 100% perfect. We no longer have the luxury of time and sitting on our hands and studying the issue.”

At least two other Colorado communities already have enacted bans on gas in new residential builds.

Crested Butte — the tiny town of about 1,700 tucked in a valley in the state’s central mountains — passed the first in 2022. Three new construction projects have started since the new code went into effect on Jan. 1, 2023, and a few new homes are in the pipeline, Crested Butte Mayor Ian Billick said.

The construction projects are for affordable housing, which shows that an all-electric can be done at scale and at an affordable price point, the mayor said.

“It’s a lot easier and cheaper in the long run to address changes before buildings are built, instead of retrofitting,” Billick said.

Crested Butte faced lobbying by the gas industry during its decision process, Billick said. Some said that switching to electric wouldn’t matter if the electricity was produced using fossil fuels, but Billick pointed out that many utilities are transitioning away from fossil fuels to renewable sources that produce fewer greenhouse gases.

“With gas, the emissions are fixed for a lifetime,” said Dannah Leeman, Crested Butte’s sustainability coordinator. “But with electric, that can change if the source improves their fuels and emissions.”

City councilors in Lafayette, the Boulder County city of about 31,000 people, in June passed a new building code that requires all-electric systems in new residential and commercial projects. The city carved out some exceptions for commercial kitchens, hospitals or labs. The new code went into effect Aug. 1.

Colorado is behind some other states on electrification in part because older technology to replace gas appliances didn’t work as well in the Rocky Mountain climate, Brinker said.

During community conversations, some people cited concerns about electric heat pumps’ effectiveness during Crested Butte’s high-altitude, sometimes frigid winters, Leeman said. But buildings in both Crested Butte and Gunnison — which is even colder — have successfully used electric heat pumps, she said. Some buildings include backup heat sources like radiated heat for the days when the temperatures drop into the negatives, she said.

In Denver, the city government is offering rebates and incentives to move toward electrification — and people are using the programs, Managan said.

“Folks understand that the change is hard but that Denver is part of the solution to climate change and they can do their part,” Managan said.

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