Boulder's energy code updates, including a ban on gas in new residential and commercial buildings, are expected to go into effect in July 2024.
Boulder's energy code updates, including a ban on gas in new residential and commercial buildings, are expected to go into effect in July 2024. Credit: Keenan Pepper

In response to the Boulder City Council’s request in June to explore a citywide gas ban in new buildings, city staff returned to council on Nov. 9 with details about what such a ban might entail.

“The energy code is one of the most effective tools we have to cut greenhouse gas emissions and encourage the transition away from fossil fuel towards renewables,” Rob Adrians, the city’s chief building official, told councilmembers last week.

The city is proposing an all-electric mandate that would apply to new residential and commercial construction — including major remodels — with some exceptions. Commercial kitchens could still use gas stoves, and laboratories and hospitals could use gas where necessary. But those buildings would have to offset any gas emissions with onsite solar.

Updated every three years, energy codes determine construction standards in the City of Boulder. With a goal to reach net-zero emissions by 2035, and recognizing that buildings make up nearly two-thirds of city emissions, stricter energy codes are one way to take a chunk out of Boulder’s contribution to climate change.

The city council’s push comes amid worsening climate change expected to increase the intensity of wildfires near Boulder, the frequency of storms that lead to flooding, and the length of dry spells that strain water sources up and down the Front Range.

The potential ban on gas in new construction comes behind other municipalities. Crested Butte has had a ban similar to what Boulder’s staff are proposing for almost a year, and Lafayette’s all-electric code went into effect on Aug. 1 this year. Denver’s ban on gas in furnaces and water heaters in commercial and multifamily construction will become law in 2024.

In their first presentation to council on the energy code updates in June, city staff did not include a ban on gas. One reason why, said Carolyn Elam, the city’s sustainability senior manager, was out of concern for lawsuits faced by other municipalities that incorporated gas bans into their energy codes. Berkeley, California, the first city in the U.S. to ban gas hook-ups in new buildings, had its ban thrown out by a judge after the city was sued by a restaurant group that said cooking over gas allows for better temperature regulation.

The exceptions built into what city staff is proposing, however, especially for commercial kitchens, could theoretically prevent such legal action.

Energy efficiency will bring savings over time

The gas ban presented by the city would affect more than just new construction. Considerable remodels — those modifying more than 50% of the floor space and replacing major mechanical equipment — would also be required to move entirely to electric appliances. And on the commercial side, new additions to buildings would be required to adhere to the new code, albeit some exceptions would also apply there.

And new residential buildings over 3,000 square feet must offset their electric use with solar, becoming net zero. And according Elam, “Most of what we’re seeing constructed in Boulder is all single family [homes] are being built 3,000 square feet or over.”

However, if a remodel doesn’t involve a complete gut, homeowners would not be required to retrofit their space.

“The intent here is to try and strike a balance, so that we don’t make scraping and starting over the more cost-effective option,” Elam said. “Preserving as much of the embodied carbon in the existing structure as possible has far greater climate benefit than the shifting from gas to electric appliances.”

In their memo, city staff acknowledged that the all-electric requirements would increase up-front construction costs. But they also said that cost savings over time from energy efficiency and reducing reliance on gas would more than offset the initial investment.

Yet cost is sometimes prohibitive. And as Boulder continues to lack adequate affordable housing, the city wants to ensure its new codes don’t prevent construction of it. The memo pointed out that because of the limited options for electric water heaters, requiring developers to use these appliances in affordable housing projects could become too expensive and financially impractical. Therefore, the memo said staff is considering the ability for the city to offer exceptions “on a case-by-case basis.”

Still, after the staff presentation, Councilmember Mark Wallach asked if city staff had fully analyzed the cost impacts of the proposed code.

“It makes me feel like we’re moving forward in a silo, and there’s a whole separate conversation … about affordable housing,” Wallach said. “It’s as though never the twain shall meet. Do you know what those impacts will look like so we can factor those in when we talk about affordable housing?”

“There’s been lots of analysis on the cost impacts on building all-electric new construction,” Elam said in response to Wallach’s question. “You’re saving money on the gas plumbing, the duct work in the home, the piping, the gas service, so that’s offsetting any incremental cost of, like, a heat pump.”

Existing buildings and next steps

Moving towards electric-only options eliminates greenhouse gas emissions only if that electricity is coming from renewable or carbon-free sources. Xcel Energy, Boulder’s electricity provider, still produces 58% of its Colorado electricity from fossil fuels — split between gas and coal. 

These codes also would only apply to new construction and remodels. To achieve drastic reductions in greenhouse gas emissions, existing buildings will eventually have to be retrofitted with electric appliances. Ithaca, New York, for example, is working to retrofit all its buildings with electric appliances by 2030 through a city-funded program. Boulder’s city staff are already exploring a range of strategies, both voluntary and regulatory, to help residents make the transition, and such conversations will be a top priority in 2024, Elam said.

City staff will present the final draft of their energy code update to the city’s Planning Board on Jan. 2, 2024, in a public hearing.

Getting adequate community feedback was something several councilmembers stressed as a priority before the final code is adopted. 

Then, staff will present it to the city council later in January, either once or several times depending on the feedback, and until councilmembers approve the code changes. The city memo said the code will go into effect April 1, 2024, but staff changed that date to July 1, 2024 in their presentation to council.

“We want to give our community and our stakeholders time to adjust to these new requirements,” Adrians said.

Tim Drugan is the climate and environment reporter for Boulder Reporting Lab, covering wildfires, water and other related topics. He is also the lead writer of BRL Today, our morning newsletter. Email:

Join the Conversation


  1. I’m a disabled senior who is living in my family home. I have gas vented heating, a gas stove and hot water heater. This new edict would require a major renovation to the home which was built in 1912 as there is no duct work at all. I want to stay in my home so would the city pay for the renovation. So many people would have to at least put in new appliances which would be a financial hardship on them as well.

    1. Doreen, this is not relevant to your place unless you are scraping or completely gutting it. “The city is proposing an all-electric mandate that would apply to new residential and commercial construction — including major remodels — with some exceptions.

  2. I have to retrofit 800 sf. of my place w/ducting for ground loop heat pump, which is a much more efficient energy source for heating/cooling than the most efficient air to air heat pump, which the city is offering free of charge to residents. Xcel provides the product and the city pays for the install, although I have been waiting 5 mos. since application. So my question is, why doesn’t the city require ducting in new-build in anticipation of subsidies for ground loop heat pumps, rather than wasting the city’s funds on antiquated air to air heat pumps that will serve only to benefit X-cel’s requirement to meet 2030 carbon goals applied to them as part of the “Partnership Agreement, ” which took the place of municipalizing the local electric supply?
    ( Carolyn said: “You’re saving money on the gas plumbing, the duct work in the home, the piping, the gas service, so that’s offsetting any incremental cost of, like, a heat pump.” She failed to specify an air to air heat pump.)

  3. No propane or natural gas. Distributive solar with localized microgrids and ground loop heat pumps. Exit Xcel. Boulder Power and Light.

  4. I’m not quite sure how the ban on natural gas hookups will effect heating our homes, and hot water heaters? Not really efficient options available right now.

  5. I agree that the much older gas appliances are not efficient. But today’s appliances are so much better. The older ones will eventually phase out naturally. I have owned an all-electric home before. Hated it. Expensive too. To heat the house was crazy. I ended up putting in a wood-burning stove to heat the house to reduce cost and get better heat. Plus most of the electricity comes from coal and natural gas. I understand that the energy companies are transitioning. But still. I would be good with establishing tighter standards on gas-burning appliances. The choice of gas or electric should still be a consumer choice, not a governmental mandate, like EVs.

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