ASHRAE 62.2-2022 Compliance in Tight Kentucky Homes: Common Field Findings HECS Documents
TL;DR
- Field-tested patterns from 2026 residential ventilation verification across Climate Zone 4A and 5A.
- Specifically, kentucky builders are delivering tighter homes than they did a decade ago.
- For example, the unintended consequence is depressurization, elevated CO₂, and moisture stratification.
Key facts
3.0 ACH50
2.5 ACH50
100 cfm
25 cfm
50 cfm
110 cfm
80 cfm
2 ACH50
Common questions this post answers
- What about The Problem: Tight Envelopes, Insufficient Mechanical Ventilation?
- What does What ASHRAE 62.2-2022 Actually Requires require?
- What about HECS Field Findings: What the Numbers Show?
- What about What HECS Verifies in the Report?
- What about Comparing Tightness vs. Ventilation Compliance?
Field-tested patterns from 2026 residential ventilation verification across Climate Zone 4A and 5A.
The Problem: Tight Envelopes, Insufficient Mechanical Ventilation
Kentucky builders are delivering tighter homes than they did a decade ago. The 2024 IECC caps envelope leakage at 3.0 ACH50 across Climate Zones 3-8 per Table R402.4.1.1, and HECS routinely measures blower door results of 1.5-2.5 ACH50 on new Louisville and Lexington custom homes. That is good for energy — and bad for fresh air.
The unintended consequence is depressurization, elevated CO₂, and moisture stratification. A tight envelope does not eliminate the need for mechanical ventilation; it amplifies it. Without a designed whole-house system, homeowners open windows in winter, defeating the air-sealing investment. Indoor CO₂ readings in the 1,200-1,800 ppm range are common in HECS field logs on homes with no dedicated ventilation equipment.
ASHRAE 62.2 is the referenced residential ventilation standard in NGBS-2023 §903 and is the default acceptance criterion for code officials reviewing tight-home compliance documentation. The standard is unambiguous: every dwelling unit requires a whole-building ventilation system sized to the equation in §4.1, with local exhaust meeting the rates in §4.3.
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Call (859) 983-7382 Get a QuoteWhat ASHRAE 62.2-2022 Actually Requires
The 2022 edition of ASHRAE 62.2 sets the residential baseline. Three requirements recur on every HECS review:
| Requirement | Section | Threshold |
|---|---|---|
| Whole-building ventilation | §4.1 | Q_total = 0.03·A_floor + 7.5·(N_br+1) cfm |
| Local kitchen exhaust | §4.3 | ≥100 cfm intermittent or ≥25 cfm continuous |
| Local bathroom exhaust | §4.3 | ≥50 cfm intermittent |
The §4.1 equation scales with conditioned floor area and bedroom count. A 2,400 ft², four-bedroom home in Lexington requires approximately 110 cfm of combined supply and exhaust ventilation. Builders who specify a single bath fan rated at 80 cfm and call it "ASHRAE 62.2 compliant" miss the calculation entirely.
ASHRAE 62.2-2022 §4.1.4 permits a filtration credit when the HVAC equipment carries a MERV-rated filter, but the credit is conditional and updated by Addendum a (Feb 2024). Misapplying the credit — claiming a 40% reduction without proper MERV verification — is one of the most common documentation errors HECS sees in third-party energy model submittals.
Infiltration credit under §4.4 is capped at the lesser of 2 ACH50 or a floor-area-derived ceiling. In Climate Zone 4A and 5A homes, that ceiling is rarely the binding constraint; mechanical ventilation almost always carries the load.
HECS Field Findings: What the Numbers Show
Across 2026 HECS project testing, three patterns dominate the field log:
- Missing or undersized supply side. Builders routinely install range hoods and bath fans (exhaust) but no matching supply. The 62.2 equation requires combined supply and exhaust. Without a dedicated supply, the home depressurizes and backdrafts combustion appliances.
- Fan curve drift. Manufacturer-rated CFM at 0.25 in. w.g. static is rarely delivered in the field. HECS measures 20-40% degradation on installed fans due to duct length, bends, and backdraft damper losses. A 100 cfm spec becomes 65 cfm at the grille.
- No commissioning documentation. §4.1 compliance requires a flow hood or CFM traverse at start-up. HECS has yet to receive a builder-supplied commissioning report that meets verifier expectations in the first round.
The downstream consequences are visible in NGBS-2023 energy modeling and ENERGY STAR MFNC functional testing checklists. A project that passes blower door and duct tightness at rough-in can still fail final inspection if §4.1 cannot be documented at startup.
What HECS Verifies in the Report
HECS delivers a ventilation compliance package tied to the ASHRAE 62.2-2022 equation, with the following items in every report:
- Calculated required CFM from §4.1 using measured conditioned area and bedroom count.
- Measured supply CFM via flow hood or duct traverse, corrected to operating static pressure.
- Measured exhaust CFM for each local exhaust terminal, with grille model and manufacturer data.
- Filtration credit worksheet if the builder is claiming §4.1.4 reduction, with filter MERV rating and pressure-drop documentation.
- Infiltration credit calculation per §4.4, capped at the lesser of 2 ACH50 or the floor-area-derived ceiling.
- Identified deficiencies with corrected-CFM recommendations.
HECS is an NCI-certified air balancing firm. CFM measurements are taken with calibrated flow hoods and digital manometers, not visual estimates. Reports are structured for direct submittal to code officials, ENERGY STAR providers, and NGBS verifiers.
Working with HECS
HECS handles ASHRAE 62.2-2022 verification for residential projects in Kentucky, North Carolina, Alabama, Georgia, West Virginia, Kansas, and Missouri. For a scope call: (859) 983-7382 or hecsusa.com/contact/.
Comparing Tightness vs. Ventilation Compliance
A common misread on HECS projects: a home that passes blower door at 2.8 ACH50 still fails 62.2 if mechanical ventilation is absent. The two requirements are independent.
| Test | Section | Pass Criterion | Common Field Result |
|---|---|---|---|
| Blower door | 2024 IECC R402.4.1.1 | ≤3.0 ACH50 (CZ 4A/5A) | 1.5-2.5 ACH50 typical |
| Duct leakage to outside | 2024 IECC R402.4.2 | ≤4 CFM25 per 100 ft² | 2-3 CFM25 per 100 ft² typical |
| Whole-building ventilation | ASHRAE 62.2-2022 §4.1 | Q_total per equation | 30-50% shortfall on first-pass installs |
| Local exhaust | ASHRAE 62.2-2022 §4.3 | Kitchen ≥100 cfm int. / Bath ≥50 cfm int. | Field-degraded 20-40% |
The ventilation line is where HECS finds the most rework. Duct tightness and blower door are increasingly well-controlled; 62.2 sizing and commissioning lag behind.
Frequently Asked Questions
Does a home that passes the 2024 IECC blower door test automatically meet ASHRAE 62.2-2022? No. The 2024 IECC envelope tightness requirement and ASHRAE 62.2 ventilation requirement are independent. A tight home can fail 62.2 if mechanical ventilation equipment is missing, undersized, or field-degraded below the §4.1 equation. HECS verifies both separately.
What documentation does an NGBS Green verifier expect for §903 ventilation compliance? NGBS-2023 §903 requires ASHRAE 62.2-2022 compliance with measured CFM at the supply and exhaust terminals. A design sheet showing fan model and rated CFM is not sufficient; flow-hood or traverse measurements at operating static are required.
Can a builder claim the §4.1.4 filtration credit without changing the HVAC filter? No. The §4.1.4 credit (updated by the February 2024 addendum) is conditional on installed MERV rating, filter pressure drop, and verified equipment airflow. HECS reviews the credit worksheet, filter specification, and blower airflow data before signing off.
How to Engage HECS
HECS performs ASHRAE 62.2-2022 verification, blower door testing, duct leakage testing, and NCI-certified air balancing for residential builders, developers, and code officials across Kentucky, North Carolina, Alabama, Georgia, West Virginia, Kansas, and Missouri. Reports are delivered in a format ready for NGBS, ENERGY STAR MFNC v1.3 (Rev05), and IRC §45L submittals. For a scope review, call (859) 983-7382 or email [email protected]. HECS also serves Louisville KY, Lexington KY, Cincinnati OH, Indianapolis IN, Nashville TN, St. Louis MO, Chicago IL, Evansville IN, and Columbus OH. Start at hecsusa.com/services/ or request a proposal through hecsusa.com/contact/.