Innovative and flexible code give local governments a framework to cut climate pollution from the fifth-largest source of greenhouse gas emissions in the state
Denver - Tuesday, Sept. 2, 2025 - The Colorado Energy Office (CEO) announced Tuesday that the Colorado Energy Code Board has published its Model Low Energy and Carbon Code. These new guidelines will increase flexibility for builders by providing multiple options to achieve efficiency by removing mandatory on-site renewable energy requirements for commercial buildings and making renewable energy voluntary. At the same time, the code will, for the first time, fairly credit energy savings from high-efficiency electric heating and water heating. This means that while the code changes do not make it more difficult to build with gas, in many circumstances high-efficiency electric heating and water heating will be the most cost-effective option.
The Model Low Energy and Carbon Code, which is required by state law HB22-1362, becomes Colorado’s new minimum energy code on July 1, 2026. Any municipality or county that updates any of its building codes after that date must adopt the model code, or a code that will achieve greater energy efficiency and pollution reductions.
This new code will help home-owners save money on energy bills by improving efficiency and reducing energy consumption in new homes and commercial buildings. Adhering to the new code will also improve indoor air quality by improving ventilation, sealing air leaks, and encouraging electrification. These actions both assist in preventing outdoor pollutants like ozone and wildfire smoke from entering buildings and decreasing interior pollutants that come from fossil fuel usage. In addition, the code will enhance climate resilience as more energy efficient buildings are more resistant to extreme temperatures — allowing homes to stay warmer longer during cold snaps or colder longer during heat waves.
“By focusing on affordable pathways to reduce energy use and greenhouse gas pollution, this code is a smart step forward in Colorado’s work to decarbonize the building sector without putting excessive burdens on developers and design teams,” said CEO Executive Director Will Toor. “Encouraging energy efficiency and the use of the highest efficiency heating systems are essential in meeting our economy-wide target of eliminating GHG pollution by 2050. But it must be done equitably and affordably, and this code does that by ensuring greater flexibility and options so jurisdictions and developers can choose the right compliance pathway for them. It balances the imperatives of minimizing construction costs and maximizing energy savings and pollution reductions, which decreases the impact on housing costs, while maximizing the benefits these communities get from higher energy savings and lower pollution.”
The code is based on a modified version of the 2024 version of the International Energy Conservation (IECC) Code, updating the state requirement from the previous 2021 version. For the vast majority of homes (those under 5,000 square feet in size), the code requirements are very similar to IECC 2024. An analysis conducted on behalf of the National Association of Homebuilders found that for most regions in Colorado, moving from IECC 2021 to 2024 would reduce construction costs for new homes by between $3,900 (for homes heated by gas) to $6,750 (for homes heated by electric heat pumps), as well as providing ongoing energy cost savings.
While the code does not mandate electrification, it fairly values the much lower energy use of highly efficient electric heat pumps compared to other forms of heating. This allows homes using these high efficiency heat pumps to achieve the same overall energy performance while having fewer requirements for other energy efficiency measures compared to those that use fossil fuel-based systems. The code focuses on reducing requirements for all-electric compliance rather than increasing requirements for mixed-fuel buildings. Both all electric and mixed fuel buildings will have viable pathways to code compliance.
In order to keep construction costs down for homeowners in homes that are more likely to serve as workforce or middle class housing or starter homes, different structure sizes will need to meet a sliding scale of energy efficiency:
Homes under 5,000 square feet have to achieve the baseline code requirements.
Homes 5,000-7,499 square feet have to achieve 7-10% better energy performance than the baseline.
Homes 7,500-plus square feet have to achieve net-zero energy.
The code is one of the first in the nation to require heating, cooling, water heating, and lighting systems to be demand response capable, which means they must be capable of automatically responding to a utility signal to reduce electricity consumption during periods of high demand. This will help utilities avoid large investments in meeting peak demand, reducing costs that would otherwise be passed on to utility ratepayers.
The code maintains existing requirements for new construction to be solar-ready, electric-ready and EV-ready, but builds in new flexibilities such as options to install Level 1 EV charging parking spaces in multifamily properties instead of Level 2 spaces.
CEO is hosting two webinars on the new code on Sept. 5 and Sept. 11 — register on the Building Energy Codes webpage. To assist in the code’s implementation, CEO is also offering a robust suite of energy code resources, including:
Technical assistance that supports local governments in drafting code amendments, public stakeholding, city council/county commission meetings, analyses, and more for new energy codes.
Training that offers virtual and in-person training options for any topic related to energy codes, available to both local government staff and building industry professionals.
Energy Code Adoption Toolkit that provides information and compliance resources to support adoption, implementation, and enforcement of energy codes.
Colorado Codes Helpline that allows any person to submit questions on building codes (not just energy codes) and receive a response from a subject matter expert within three business days.
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