ERV vs HRV selection: ERV in hot-humid (recovers humidity); HRV in cold-dry (avoids excess winter humidity)
BASC Guide — guides/whole-house-erv-hrv-designDescription
Energy/Heat Recovery Ventilators recover sensible (HRV) or sensible + latent (ERV) energy from outgoing exhaust to precondition incoming fresh air. Selection: HRV in cold-dry climates (CZ 6-8 + dry regions of 4-5) — avoids winter humidity buildup; ERV in mixed-humid + hot-humid climates (CZ 1-3 + humid 4-5) — recovers moisture in cooling season + dries supply in heating season. Sizing per ASHRAE 62.2. Dedicated ducting (separate from heating ducts) gives better control than HVAC-integrated.
Why this exists
The HRV vs ERV choice is climate-zone specific — wrong choice penalizes either humidity control or comfort. For NY (mixed-humid CZ 4-6), an ERV with bypass mode for winter is the typical residential default.
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.