Windows must be ENERGY STAR certified (climate-zone-specific U-factor + SHGC); skylight + door requirements similar
ENERGY STAR SFNH §Fenestration — Energy Star windowsDescription
All windows must be ENERGY STAR certified for the project's climate zone — the certification requires the window's U-factor + SHGC (solar heat gain coefficient) meet zone-specific maximums per the EnergyStar.gov fenestration program. Doors with glazing > 50% must also meet the standards; skylights have stricter U-factor + SHGC because of their orientation.
Why this exists
Windows are the weakest thermal point in the envelope. The ENERGY STAR climate-zone tables let the architect specify by performance number rather than chasing brand names. Most quality residential window manufacturers offer multiple options that hit the zone targets; specify by U-factor + SHGC on the schedule, not by name.
Categories
Source
Solver enforcement
Browsable only — the solver does not currently enforce this directive (no spec-level data to check against). This entry exists so the architect personas can cite it in conversation and the user can read what the rule says.
Related directives
- Slab-on-grade vapor barrier + capillary break required · HUD RSDG §4.6
- Roof overhangs protect walls — 12-24 inches in humid climates; one foot per story below · HUD RSDG §5.6.5
- ENERGY STAR certification: HERS-index target + Rater field checklist + HVAC quality install · ENERGY STAR SFNH §Overview — Certification path
- Grade I insulation installation: no gaps, no compression, fully filling cavity, supported aligned with air barrier · ENERGY STAR SFNH §Rater Field Checklist — Section 1 (Insulation + Air Barrier)
- Continuous air barrier on all six sides of conditioned space — including rim joists, knee walls, attic floor · ENERGY STAR SFNH §Air Barrier — continuous on all six sides of every conditioned space
Last reviewed 2026-05-15.