Energy Efficiency Resource Standard:

In 2021, Colorado established binding energy efficiency targets for both electricity and natural gas utilities (SB21-264): 

• Electric utilities must reduce retail system peak demand by 5% by 2028, compared to 2018 levels, and achieve annual energy savings of 440 GWh during 2024–2026.
• Gas utilities are required to deliver increasing energy savings: 814,000 dekatherms (Dth) in 2024, 860,000 Dth in 2025, and 903,000 Dth in 2026.

Building Codes:

Since 2019, local jurisdictions in Colorado are required to adopt one of the three most recent versions of the IECC at a minimum (HB 19-1260). Colorado’s Air Quality Control Commission was required, in 2021, to adopt regulations to ensure 20% reduction in GHG emissions below 2020 levels by 2030 from existing buildings over 50,000 square feet (HB 21-1286). In 2022, Colorado established requirements to adopt the most recent IECC in new buildings, prewire for electric vehicles, solar and heat pumps, and locally adopt a low carbon code starting in 2026 toward near net zero building energy codes by 2030 (HB 22-1362). Subsequent legislation in 2025 updated the states building performance standards by requiring performance standards through 2040 (HB25-1269). Starting July 1, 2026, all cities and counties must adopt the state’s Model Low Energy and Carbon Code regulations whenever they update local building codes or adopt local building efficiency rules. 

Appliance Standards:

In 2019, Colorado updated and adopted standards for water efficiency and energy efficiency that apply to 15 appliances and other products (HB19-1231). In 2023, Colorado adopted new or updated appliance standards for 14 products and clean lighting (HB23-1161). This bill was subsequently amended to align with 2024 IECC with the following alternative statewide U-factor requirements, effective Jan. 1, 2026: 

• Windows: U-factor ≤ 0.30
• Skylights: U-factor ≤ 0.50
• Residential doors with more than half glass: U-factor ≤ 0.30
• Opaque and ≤½-lite doors: Exempt