California Energy Code · Climate Zone 2
Title 24 Compliance 2026
California's 2026 Title 24 energy code requires window assemblies to achieve a U-factor of 0.27 or lower in Climate Zone 2, and NFRC-rated window treatments count toward compliance by improving the fenestration assembly performance.
The 2026 update to California's Title 24 Building Energy Efficiency Standards is the most significant tightening of fenestration requirements in over a decade. For homeowners and builders in Sonoma County's Climate Zone 2, the new U-factor threshold of 0.27 means standard dual-pane glass alone no longer qualifies. Typical dual-pane Low-E windows carry a U-factor around 0.30, falling short of the 2026 standard. Window treatments with NFRC ratings offer a practical compliance pathway that avoids full window replacement. A triple-cell Duette Architella shade adds R-7.86 of thermal resistance to the assembly, dropping the combined U-factor to 0.23 and exceeding the code requirement with margin to spare. Discount Best Blinds and Shutters specifies Title 24 compliant products for every new construction and retrofit project across Sonoma County, providing the NFRC documentation your architect or energy consultant needs for permit submission.
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Title 24 documentation that clears Climate Zone 2 permits
Title 24 2026 sets strict fenestration U-factor and solar heat gain targets, and the right window treatments help projects exceed them. Duette Architella's 0.23 assembly U-factor beats the 0.27 threshold by roughly 15%, while solar shades at 1–3% openness meet west-facing SHGC limits of 0.17 and below. Every recommendation is tuned to Sonoma County's Climate Zone 2, and every install is cordless or motorized to meet ANSI/WCMA A100.1-2022. We supply the specification-grade U-factor and SHGC data your permit submittal needs.
Window treatments bridge the gap. When a shade or blind with an NFRC rating is installed on a window, the combined assembly's thermal performance improves measurably. Duette Architella triple-cell shades contribute R-7.86 to the assembly, yielding a shade-only U-factor of 0.127. Paired with dual-pane Low-E glass, the combined window assembly achieves a U-factor of 0.23, exceeding the 2026 requirement by a meaningful margin. This makes cellular honeycomb shades the most effective single product for Title 24 compliance, particularly in retrofit scenarios where window replacement is cost-prohibitive or architecturally undesirable.
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What this solution includes
Exceeds U-Factor Target
Duette Architella assembly U-factor of 0.23 beats the Title 24 2026 threshold of 0.27 by roughly 15%.
Meets SHGC Limits
Solar shades at 1%–3% openness meet the west-facing SHGC ≤ 0.17 and south-facing ≤ 0.22 requirements.
Climate Zone 2 Experience
Recommendations tuned to Sonoma County's Climate Zone 2, with summer temps of 75–95°F and strong west sun.
Permit Documentation
We supply specification-grade U-factor and SHGC data for builder permit and code-compliance submittals.
Child-Safety Compliant
Every installation is cordless or motorized to meet ANSI/WCMA A100.1-2022.
The details
- Fenestration U-Factor
- ≤ 0.27 required · 0.23 delivered
- West-Facing SHGC
- ≤ 0.17 (solar 1%–3% openness)
- South-Facing SHGC
- ≤ 0.22 (solar + Silhouette)
- Climate Zone
- Zone 2 (Sonoma County)
- Child Safety
- ANSI/WCMA A100.1-2022
Recommended products
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FAQ
Frequently Asked Questions
Title 24 is the California Building Energy Efficiency Standards, administered by the California Energy Commission. The 2026 update takes effect January 1, 2026 and requires window assemblies to achieve a U-factor of 0.27 or lower in Climate Zone 2, which covers Sonoma County. This represents a significant tightening from the previous cycle and affects both new construction and major retrofit projects that trigger permit requirements. Window treatments with NFRC ratings can be included in the overall window assembly calculation, making them a practical compliance pathway for homeowners and builders.
Yes. NFRC-rated window treatments are recognized by the California Energy Commission as part of the fenestration assembly for Title 24 compliance calculations. When a window treatment is paired with the existing glass, the combined U-factor of the assembly improves significantly. For example, standard dual-pane Low-E glass has a U-factor around 0.30, which fails the 2026 threshold of 0.27. Adding Duette Architella triple-cell shades brings the combined assembly U-factor down to approximately 0.23, well within compliance. Discount Best Blinds and Shutters provides documentation for Title 24 submissions on every qualifying installation.
U-factor measures heat transfer through the window assembly. A lower U-factor means better insulation. The 2026 Title 24 threshold for Climate Zone 2 is U-factor 0.27 or lower. SHGC (Solar Heat Gain Coefficient) measures how much solar radiation passes through the glass and enters the home as heat. Lower SHGC values mean less solar heat gain. For west-facing windows in Sonoma County, a target SHGC of 0.17 or lower is recommended to control afternoon heat, while south-facing windows target 0.22 or lower. Both metrics matter for compliance, and different window treatment products excel at each.
Title 24 applies to new construction, additions, and alterations that trigger a building permit. If you are replacing more than a certain percentage of your windows, adding a room, or performing a major renovation, Title 24 compliance is required. For existing homes not undergoing permitted work, Title 24 is not mandatory, but upgrading to compliant window treatments still delivers meaningful energy savings and increases property value. The retrofit compliance pathway allows NFRC-rated window treatments to count toward the assembly U-factor, making it possible to bring older windows into compliance without replacing the glass.
Discount Best Blinds and Shutters provides complete NFRC certification documentation for every qualifying Hunter Douglas product installation. This includes the NFRC-rated U-factor and SHGC values for the window treatment, the combined assembly performance calculation when paired with your existing or specified glass, and the product certification number for inclusion in your Title 24 compliance filing. Phil D. Skikos coordinates directly with your architect, general contractor, or energy consultant to ensure all documentation meets California Energy Commission submission requirements.