Designed to reach net-zero energy with available rooftop area; HERS index ≤ 0 after PV installation
DOE ZERH §Specific renewables target — net-zero capabilityDescription
ZERH-certified homes must be designed such that, with a properly-sized solar PV system installed on available rooftop area, the home would achieve a HERS Index of 0 or less (i.e. produce as much energy annually as it consumes). The 'available rooftop' calculation uses the south-facing roof area minus shading, vents, skylights, etc. — typically a 5-8 kW PV array depending on home size + climate.
Why this exists
This is the 'Zero Energy READY' guarantee — even if the homeowner doesn't install PV at construction, the architecture is conducive to it later. Architects designing toward ZERH should explicitly model the PV-installed HERS in the energy model from the start; finding out the home falls short after construction is a costly re-engineering ask.
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.