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  • How does the Mlecc Affect Residential Window Requirements after July 1, 2026?
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Starting July 1, 2026, the Model Low Energy and Carbon Code (MLECC) significantly tightens window performance standards for residential projects across most Colorado jurisdictions. These updates focus on specific efficiency metrics to reduce carbon emissions and heat transfer.

Key requirements and jurisdictional differences include:

  • Denver, Centennial, and Unincorporated Arapahoe County: These areas have the most stringent requirements. Windows must achieve a U-value of 0.30 or lower and a Solar Heat Gain Coefficient (SHGC) of 0.25 or lower.
  • Colorado Springs: This jurisdiction has delayed full adoption until 2027 and maintains slightly more flexible thresholds, requiring a U-value of 0.35 and an SHGC of 0.30.
  • Energy Star Alignment: The new thresholds are designed to align with the Energy Star window requirements 2026 Colorado standards. Selecting high-performance products, such as fiberglass windows, helps meet these benchmarks.
  • Tax Credit Eligibility: Homeowners who install windows meeting these heightened standards may become eligible for the Energy Star Most Efficient 2026 tax credit, helping to offset the cost of high-performance upgrades.

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