Field-tested observations from Kentucky blower-door and ventilation commissioning in 2026.

The Problem: Tight Envelopes Are Outpacing Ventilation Design

Kentucky sits in IECC Climate Zones 4A and 5A. Under the 2024 IECC Table R402.4.1.1, homes in those zones must test at or under 3.0 ACH50 — not the 5.0 figure builders associate with older code cycles. HECS routinely measures new Kentucky construction in the 1.5–2.5 ACH50 range, especially ENERGY STAR and NGBS-targeted projects chasing HERS scores in the 50s.

That airtightness is a code win, but it exposes a second-order failure: when an envelope drops below roughly 2 ACH50 without deliberate mechanical ventilation, whole-building fresh-air delivery collapses. Indoor CO₂ climbs above 1,200 ppm, humidity spikes in shoulder seasons, and HECS sees formaldehyde and VOC complaints that have no obvious source. The blower door passed. The house is not ventilating.

ASHRAE 62.2-2022 addresses acceptable indoor air quality in low-rise residential buildings, and compliance is now layered on top of the airtight envelope that 2024 IECC demands.

The Standard: ASHRAE 62.2-2022 and the §4.1 Equation

The whole-building ventilation rate required by ASHRAE 62.2-2022 follows the formula in §4.1: Q_total = 0.03·A_floor + 7.5·(N_br+1), expressed in cfm, where A_floor is conditioned floor area in square feet and N_br is the number of bedrooms. A 2,400 ft², four-bedroom home in Louisville therefore needs roughly 110 cfm of combined supply and exhaust ventilation — a non-trivial airflow that no builder accidentally delivers through a bath fan and a fresh-air damper.

The standard's §4.1.4 filtration credit (updated by Addendum a, February 2024) lets MERV-rated HVAC equipment reduce required mechanical ventilation. §4.3 sets local exhaust thresholds for kitchens and bathrooms. §4.4 caps the infiltration credit — the contribution of natural leakage to compliance — at the lesser of 2 ACH50 or 0.04·A_floor / 7.6 cfm. In a tight Kentucky home, that infiltration contribution is functionally zero, which pushes the entire compliance burden onto the mechanical system.

NGBS-2023 §903 cites ASHRAE 62.2-2022 directly for its Indoor Environmental Quality chapter, and ENERGY STAR MFNC v1.3 (Rev05) carries ASHRAE 62.2 into multifamily ventilation checklists. Code officials enforcing 2024 IECC in Kentucky, Indiana, or Ohio should expect — and verify — documentation against these cross-referenced citations, not just a blower door number.

HECS Recommendation: Treat Ventilation as a Commissioned System

HECS treats ASHRAE 62.2-2022 compliance as a commissioned deliverable, not a design note on the plans. The HVAC sub walks the job with a NCI Residential Air Balancer setup and verifies five things in sequence.

First, the calculated required ventilation rate from §4.1, recorded on a per-unit worksheet with the conditioned floor area and bedroom count called out.

Second, the as-installed airflow at every supply and exhaust terminal under design operating conditions — not at the nameplate rating on the fan curve. HECS finds bath fans running 30–80% off nameplate once static pressure is real.

Third, the filtration credit claimed under §4.1.4, documented with the MERV rating stamped on the installed filter track.

Fourth, the local exhaust rates per §4.3, with kitchen and bath terminal readings.

Fifth, the operating schedule — runtime hours, fan speed setting, controls interlocks.

A passing blower door is the entry ticket, not the finish line.

Common Field Findings HECS Documents

HECS works on roughly 90+ certified projects across Kentucky, North Carolina, Alabama, Georgia, West Virginia, Kansas, and Missouri. The same failures repeat.

Ventilation fans wired but capped. The fresh-air duct terminates at a manual damper that nobody opened, or the ERV is installed but the condensate trap is dry and the blower never spun up under functional test.

Filtration credit claimed without verification. The filter slot holds a MERV-13, but the equipment was not designed to handle the static penalty. The blower drops to low speed, airflow at the registers falls out of spec, and the credit evaporates.

Local exhaust undersized. A 50 cfm bath fan on a 9 ft ceiling with an 8 ft duct run can deliver 30 cfm or less by the time static pressure is paid. §4.3 sets a target; the field measurement is what counts.

Infiltration credit overstated. Plans cite a 4 ACH50 envelope and a 40 cfm natural contribution; the blower door comes back at 1.8 ACH50 and the credit is gone.

Working with HECS

HECS handles ASHRAE 62.2-2022 ventilation commissioning and indoor-air-quality verification for builders across Kentucky, North Carolina, Alabama, Georgia, West Virginia, Kansas, and Missouri. The deliverable is a per-unit compliance report that code officials, raters, and NGBS verifiers can sign off without re-inspection. For a scope call: (859) 983-7382 or hecsusa.com/contact/.

What HECS Verifies in the Final Report

Every HECS ASHRAE 62.2-2022 report includes the §4.1 calculation with inputs shown, measured airflow at each supply and exhaust terminal, blower door result used for the §4.4 infiltration credit, the filter MERV rating and the credit claimed under §4.1.4, and a pass/fail line against each numeric threshold the standard sets.

For projects pursuing ENERGY STAR, NGBS, or FORTIFIED certification, the same report feeds directly into the verifier's submission package — no rework, no duplicate site visit. The HECS scope includes indoor-air-quality testing, blower door, duct leakage, and radon screening, so a single mobilization covers the commissioning checklist. Builders in Louisville KY, Lexington KY, Cincinnati OH, and Indianapolis IN typically receive the report within five business days of the final site visit.

Frequently Asked Questions

Does a passing blower door satisfy ASHRAE 62.2-2022 on its own?

No. The blower door result contributes to the §4.4 infiltration credit, which is capped at the lesser of 2 ACH50 or roughly 0.04·A_floor / 7.6 cfm. In a tight Kentucky home, that contribution is small; the mechanical ventilation system must still be commissioned and documented to demonstrate compliance with the §4.1 equation.

How does the 2024 Addendum a change ASHRAE 62.2-2022 compliance documentation?

Addendum a updates §4.1.4 to clarify how MERV-rated HVAC equipment can reduce required mechanical ventilation. HECS documents the filter MERV rating, the equipment's ability to handle the resulting static, and the credit applied — claimed crediting without that documentation fails the verifier review.

Can NGBS-2023 and ASHRAE 62.2-2022 share the same field report?

Yes. NGBS-2023 §903 cites ASHRAE 62.2-2022 directly, and a HECS report structured around the ASHRAE sections satisfies both the green standard and the indoor-air-quality checklist for ENERGY STAR MFNC v1.3 (Rev05).

How to Engage HECS

HECS delivers ASHRAE 62.2-2022 commissioning alongside blower door, duct leakage, radon, and indoor-air-quality testing for projects in Kentucky, North Carolina, Alabama, Georgia, West Virginia, Kansas, and Missouri. The deliverable is a code-official-ready report with measured airflow at every terminal, the §4.1 calculation, and the filtration credit documentation. HECS also serves Louisville KY, Lexington KY, Cincinnati OH, Indianapolis IN, Nashville TN, St. Louis MO, Chicago IL, Evansville IN, and Columbus OH with the same scope. For scheduling, call (859) 983-7382 or email [email protected], or submit through hecsusa.com/contact/ and hecsusa.com/services/.