Whole-building fresh-air requirements under the 2022 standard, what HECS verifies in the field.

Why 62.2 Matters More Than Builders Realize

ASHRAE 62.2-2022 (Ventilation and Acceptable Indoor Air Quality in Low-Rise Residential Buildings) is the ventilation reference embedded in IRC Section M1505, the 2024 IECC, ENERGY STAR v3.1/v3.2, NGBS-2023, and EarthCraft. Code officials in Kentucky, Indiana, and Ohio routinely cite it as the tie-breaker when local amendments are silent. HECS project data shows that ventilation shortfalls, not envelope airtightness, drive the majority of failed ENERGY STAR and NGBS submittals on garden-style multifamily.

The standard splits the problem into two engine blocks: a whole-building requirement driven by floor area and bedrooms, plus an infiltration credit when blower-door numbers are tight enough. Add point-source exhaust for kitchens and baths, and the building either passes or it doesn't. There is no judgment call.

The Three Engine Blocks

• Whole-building ventilation, a continuous mechanical supply or balanced system sized to the equation in §4.1.
• Infiltration credit, a deduction allowed when blower-door-tested leakage is low enough to justify reduced mechanical runtime.
• Local exhaust, point-source fans in kitchens and bathrooms meeting §5 flow targets.

What the Standard Actually Requires

Section 4.1 sets the total required ventilation rate. Section 4.4 limits the credit that blower-door results can subtract from that rate. Section 5 lists minimum local-exhaust flows. Builders who treat the standard as "one HRV, one kitchen fan, move on" routinely fail third-party review. HECS finds the typical failure pattern is a fan that is undersized relative to the §4.1 number, paired with an envelope too leaky to qualify for any §4.4 credit at all.

A practical rule of thumb from HECS field work: total required ventilation on a 1,200-2,400 ft² multifamily unit commonly lands in the 70-110 cfm range before any credit is applied. The exact number depends on floor area and bedroom count.

Working with HECS

HECS performs blower-door testing and ventilation verification for multifamily projects across Kentucky, Indiana, Ohio, Tennessee, Illinois, and Missouri. We measure leakage, confirm fan flow against §4.1 targets, and document the compliance package your rater or verifier needs. For a scope call: (859) 983-7382 or hecsusa.com/contact/. More on our multifamily ventilation and blower door services at hecsusa.com/services/.

The Infiltration Credit, Where Projects Gain or Lose

The §4.4 credit only kicks in when blower-door results clear a code-defined threshold. The standard's credit formula is more nuanced than a single ACH50 cap, and HECS treats the published language as the only safe reference. Based on HECS project data, garden-style units in Climate Zone 4 (which covers most of Kentucky, southern Indiana, and southwestern Ohio) typically need to test at roughly 2-3 ACH50 or tighter before any credit materializes, looser envelopes default to 100% mechanical ventilation.

This is the section that most often trips code officials. A builder submits a ventilation design assuming credit; the blower-door reading comes back at 4 ACH50; the design no longer complies. Resizing the HRV after the rough-in walkthrough is the expensive path. HECS recommends a pre-drywall blower-door test on at least one representative unit per building, see hecsusa.com/blower-door-testing-lexington-ky/ for the Lexington-area service description.

Local Exhaust and the Point-Source Layer

Section 5 requires local exhaust in every bathroom and kitchen. The standard specifies minimum airflow rates, typically 50 cfm for baths and 100 cfm for kitchens, though the exact values should be confirmed against §5.1 of the current edition before submittal. Fans must vent to the outdoors, not into the attic or soffit.

Continuous runtimes versus intermittent operation matter. A 25 cfm continuous bath fan counts differently under §4.1 than a 50 cfm intermittent fan, the standard treats them as distinct credit types. HECS sees far more confusion on this point than on any other §5 issue.

For multifamily corridors, builders also need to reconcile §5 with NFPA 54 combustion-air requirements when gas ranges or furnaces share walls with adjacent units. HECS coordinates with mechanical contractors to verify both standards are satisfied before ceiling close.

Coordinating 62.2 With Certification Programs

ENERGY STAR v3.1/v3.2 for multifamily new construction references ASHRAE 62.2 directly. NGBS-2023 Chapter 7 incorporates 62.2 by reference and adds a few prescriptive options. EarthCraft Multifamily uses 62.2 as the baseline ventilation target. A single compliance package satisfying one program generally satisfies the others, provided the documentation aligns with the rater's checklist.

HECS delivers the verification report in the format each program requires. For projects pursuing 45L tax credit certification, the §45L residential credit extension has been a moving target and HECS verifies the current statutory date against the latest guidance before signing off, the same blower-door and ventilation data feeds the energy model. See hecsusa.com/45l-tax-credit-louisville-ky/ for the Louisville-area scope.

Frequently Asked Questions

Does ASHRAE 62.2 require mechanical ventilation in every unit, even with a tight envelope?

Yes. The standard allows an infiltration credit against the §4.1 whole-building requirement, but a mechanical system of some kind must be present and verified. The standard does not let a builder skip mechanical ventilation entirely. HECS sees multifamily projects where developers assumed "tight enough = no fan needed" and failed ENERGY STAR review as a result.

How does 62.2 interact with the 2024 IECC for Kentucky projects?

The 2024 IECC references 62.2 by way of IRC M1505. Where Kentucky has adopted the 2024 IECC, code officials enforce 62.2 as the ventilation standard. HECS confirms local adoption status at the start of each project, Lexington and Louisville have moved on different timelines historically, and the Louisville Metro inspection cycle is the controlling reference for most Kentucky multifamily.

What documentation does HECS deliver for 62.2 compliance?

HECS provides a ventilation verification report including blower-door results, measured exhaust fan flows, the calculated §4.1 total, the §4.4 credit (if applicable), and a compliance summary keyed to the program checklist, ENERGY STAR, NGBS, or EarthCraft. The report is formatted for direct upload to the rater's file and includes the calibration certificates for the equipment used.

How to Engage HECS

HECS handles blower-door testing, ventilation verification, and full certification support for multifamily projects across Kentucky, Indiana, Ohio, Tennessee, Illinois, and Missouri. Our service area covers Louisville KY, Lexington KY, Cincinnati OH, Indianapolis IN, Nashville TN, and St. Louis MO, with project reach extending to Evansville IN, Columbus OH, and Chicago IL. Reach the team at (859) 983-7382 or [email protected]. Full scope descriptions at hecsusa.com/services/ and hecsusa.com/contact/.