Mechanical ventilation is no longer optional once a home drops below roughly 3 ACH50.
The 2024 IECC and ENERGY STAR v3.2 both push residential envelopes toward blower door readings typically between 3 and 5 ACH50. At that tightness, natural infiltration can no longer provide the dilution ventilation ASHRAE 62.2 assumes.
What HECS sees in the field:
ASHRAE 62.2-2022 is explicit: local exhaust must operate to the listed flow, and whole-house mechanical ventilation must deliver the calculated rate based on floor area and number of bedrooms. Neither requirement is satisfied by equipment selection alone.
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Call (859) 983-7382 Get a QuoteASHRAE 62.2 defines two required functions in every dwelling unit — local exhaust and whole-house ventilation. Local exhaust covers kitchens and bathrooms at listed airflows. Whole-house ventilation is calculated using the normative equation:
Q = 0.03 × A_floor + 7.5 × (N_br + 1)
where A_floor is conditioned floor area in square feet and N_br is the number of bedrooms. The result is the minimum continuous CFM.
The standard further requires:
For ENERGY STAR v3.2 homes, ASHRAE 62.2-2019 or later must be verified by a RESNET-certified Rater through the HVAC checklist. NGBS-2023 references 62.2 directly for its indoor air quality section.
HECS approaches 62.2 the same way we approach a TAB report — measure, document, and sign only what passes. Our indoor air quality workflow begins before the insulation is closed.
Pre-drywall verification confirms duct leakage to outside against the 2024 IECC thresholds using a Duct Blaster at 25 Pa, and confirms that ventilation supply and exhaust penetrations are routed, dampered, and accessible for later testing.
Final verification uses calibrated flow hoods, capture hoods on diffusers, and a micro-manometer on the ventilation supply to capture true delivered CFM against the calculated target. For HRV and ERV installations, HECS confirms both supply and exhaust sides are within the manufacturer balance tolerance, typically cited as a percentage deviation from nameplate.
| Verification Point | Test Method | Pass Criterion |
|---|---|---|
| Local exhaust (bath/kitchen) | Capture hood at grille | Meets ASHRAE 62.2 listed flow |
| Whole-house supply CFM | Flow hood at terminal | Within 10% of design Q |
| HRV/ERV balance | Capture hood, supply and return | Within mfr. tolerance |
| Duct leakage to outside | Duct Blaster at 25 Pa | Per 2024 IECC table |
For projects pursuing the 45L tax credit under IRC §45L, this documentation supports the energy efficiency certification HECS files through RESNET protocols. Builders who skip the verification step frequently lose the credit at audit.
Every 62.2 verification produces a written report delivered in PDF. The report includes the calculated whole-house ventilation rate from floor area and bedroom count, the measured local exhaust CFM for each bath and kitchen, and the measured whole-house supply CFM with the static pressure observed at the terminal.
The report also flags common installation defects — supply duct routed through unconditioned attic without insulation, exhaust fan terminated in soffit instead of roof, controls wired so the fan only runs with the light switch. These are the items code officials and HERS Raters look for during field review.
HECS does not install ventilation equipment or perform HVAC design. The firm verifies what is already installed against the cited standard. When the installation fails, the report identifies the specific deficiency so the builder can correct it before the next inspection.
What ASHRAE 62.2 ventilation rate does my home need? The required whole-house rate is calculated from the equation 0.03 × conditioned floor area plus 7.5 × (bedrooms + 1), yielding a continuous CFM target. Local exhaust must additionally meet the listed rates for each bathroom and kitchen. HECS performs the calculation and confirms field-measured flow against it.
Does ASHRAE 62.2 apply to renovations or only new construction? The standard applies to all dwelling units once a whole-house mechanical ventilation system is introduced. In practice, additions and gut rehabs in Kentucky and Indiana jurisdictions trigger 62.2 through the 2024 IECC adoption. HECS scopes per project to determine the applicable baseline.
Can a bath fan satisfy the whole-house requirement? No. ASHRAE 62.2 separates local exhaust (intermittent, high-flow) from whole-house ventilation (continuous or equivalent, calculated rate). A bath fan running on a humidity sensor does not meet the whole-house equation. HECS documents both functions independently in the verification report.
HECS performs ASHRAE 62.2 verification, blower door testing, and duct leakage testing as standalone scopes or bundled with ENERGY STAR, NGBS Green, or EarthCraft certification across Kentucky, Indiana, Ohio, Tennessee, Illinois, and Missouri. Scheduling is fastest at rough-in for pre-drywall duct leakage and at final for ventilation and envelope verification. Call (859) 983-7382 or email hecs@hecsusa.com to scope a project. Service details and the request form are at hecsusa.com/services/ and hecsusa.com/contact/.
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