The 2022 standard's mechanical ventilation rule meets today's blower-door-tight envelopes, and the math doesn't always work out.

Why Tight Kentucky Homes Create a 62.2 Problem

HECS tested residential projects across Kentucky and southern Indiana in 2024-2025, and one pattern repeats: as envelope airtightness improves to meet the 2024 IECC, natural infiltration alone can no longer carry the ventilation load. Louisville and most of Kentucky fall in IECC Climate Zone 4A, with northeastern counties in CZ 5A, both under the binding 3.0 ACH50 ceiling per the 2024 IECC Table R402.4.1.1. When blower-door results land near 2.5-3.0 ACH50, builders assume the house "breathes enough." It doesn't, and that's where ASHRAE 62.2-2022 enters the project.

The field failure is consistent. Builders tighten the envelope to satisfy the energy code, then install a single bathroom exhaust fan and call it compliant. A site-built test under ASHRAE 62.2-2022 usually shows the required whole-building ventilation rate is roughly double what the installed fan delivers. Documentation gaps follow: no measured airflow, no per-room exhaust verification, no MERV credit calculation. Code officials in Jefferson County and Boone County have started asking for the actual 62.2 worksheet.

What ASHRAE 62.2-2022 Actually Requires

The 2022 edition specifies a whole-building mechanical ventilation rate governed by an equation, 0.03 × conditioned floor area plus 7.5 × (bedrooms + 1), in cubic feet per minute, applied per ASHRAE 62.2-2022 §4.1. For a 2,400 ft² Kentucky home with three bedrooms, that equation yields a required mechanical ventilation rate in the 100-130 cfm range. Local exhaust rules under §4.3 require kitchen range hoods at ≥100 cfm intermittent or ≥25 cfm continuous, and bathrooms at ≥50 cfm intermittent.

Filtration credit under §4.1.4, updated by the February 2024 addendum, lets MERV-rated central equipment reduce the required mechanical rate, but only when the equipment is verified installed and operating. Infiltration credit under §4.4 is capped at the lesser of 2 ACH50 or a floor-area-derived limit; in practice on tight Kentucky homes, that credit collapses to near zero and the mechanical system carries the entire load.

Working with HECS

HECS runs ASHRAE 62.2-2022 calculations and on-site airflow verification for builders, code officials, and developers throughout Kentucky, Indiana, Ohio, Tennessee, Illinois, and Missouri. For a scope call: (859) 983-7382 or hecsusa.com/contact/.

HECS Field Findings: What the Data Shows

Across recent residential projects, HECS documentation reveals recurring deficiencies that survive rough-in and finish-out inspections. The most common findings:

• Required 62.2 rate exceeds installed fan capacity by 30-60%
• Bathroom exhaust fans measured at 30-40 cfm when 50 cfm is required; flex duct runs crush airflow by 15-25%
• Range hoods ducted through attics with no insulation on the duct, dropping effective ventilation by 20-30%
• MERV filtration credit claimed on the worksheet but no filter installed at commissioning
• Local exhaust fans on shared switching with lights, defeating continuous operation

HECS verifies the actual installed airflow using a flow-hood or capture-hood per NCI residential air-balancing procedures, then cross-checks against the 62.2 worksheet. The deliverable is a stamped compliance letter with measured CFM at each device, calculated total required CFM, and a pass/fail designation.

What HECS Verifies and Documents

Each ASHRAE 62.2-2022 compliance package from HECS includes the calculated required ventilation rate per the standard's equation, measured airflow at every exhaust terminal, and a recorded blower-door result used to verify the infiltration credit. The package flags the 2024 IECC airtightness threshold for the project's climate zone per the DOE Building America climate-zone map, 3.0 ACH50 for all HECS-served counties, so the builder sees both code lines in one document.

For projects pursuing ENERGY STAR MFNC v1.3 Rev05 or NGBS-2023 certification, HECS cross-references the 62.2 documentation against the functional-testing checklist and NGBS Chapter 7 requirements. Sampling per ANSI/RESNET/ICC 380 is applied where the program allows.

Common Pitfall: Confusing 62.2 with the Energy Code

ASHRAE 62.2 is a ventilation standard; the 2024 IECC airtightness limits are an energy-conservation rule. Both apply simultaneously but verify different things. A house passing the blower-door test at 2.8 ACH50 can still fail 62.2 if the mechanical ventilation system is undersized or uncontrolled. HECS documentation addresses both with separate measurement sheets, one for envelope airtightness, one for ventilation airflow.

Frequently Asked Questions

Does ASHRAE 62.2-2022 apply to single-family homes in Kentucky, or only multifamily?

ASHRAE 62.2-2022 applies to any residential dwelling, single-family, multifamily, low-rise, and townhouse. The standard is referenced explicitly by NGBS-2023 §903 and is the de facto ventilation rule for ENERGY STAR-certified units. HECS verifies 62.2 compliance for builders regardless of program path.

What is the required whole-building ventilation rate for a typical 2,400 ft² Kentucky home with three bedrooms?

Per the equation in ASHRAE 62.2-2022 §4.1, the required rate is approximately 0.03 × 2,400 + 7.5 × (3+1) ≈ 102 cfm before any filtration credit. With MERV 13 credit applied per §4.1.4, the effective rate can drop, but only if the filter is verified installed at the furnace or air handler.

Can a builder claim compliance using only infiltration, without a mechanical system?

Rarely, and only on leaky homes. The §4.4 infiltration credit caps at the lesser of 2 ACH50 or a floor-area-based formula; on a tight Kentucky home at 2.5-3.0 ACH50, the credit is small. HECS documentation almost always shows mechanical ventilation is required to meet 62.2 alongside 2024 IECC airtightness targets.

How to Engage HECS

HECS provides ASHRAE 62.2-2022 compliance testing, blower-door verification, and duct leakage testing across Kentucky, Indiana, Ohio, Tennessee, Illinois, and Missouri. Each project is staffed by an NCI-certified technician using calibrated residential instruments, with deliverables suitable for code officials, program raters, and developer compliance files. To schedule a residential or multifamily scope call, call (859) 983-7382, email [email protected], or submit a request through hecsusa.com/contact/. Service offerings are listed at hecsusa.com/services/. HECS also serves Louisville KY, Lexington KY, Cincinnati OH, Indianapolis IN, Nashville TN, and Evansville IN as primary city clusters, see the indoor-air-quality service page for the full geographic reach.