What developers, custom builders, and code officials are actually paying HECS this year, and which thresholds gate each test.
Certification deadlines have moved earlier in the construction calendar. The federal energy-efficient home credit under IRC §45L sunsets for projects that do not reach certification by the deadline codified in the One Big Beautiful Bill Act, and HECS has watched builders lose eligibility on paperwork lag that one extra site visit would have prevented.
Three line items dominate the pre-drywall budget for Louisville, Lexington, and Cincinnati-area projects: a blower door test, a duct leakage test run in rough-in mode, and, when ENERGY STAR or ZERH is the program, the field verifications that convert rough scores into a certified home. The dollar figures below are drawn from HECS invoices issued Q1 2026 across Kentucky, Indiana, and Ohio.
For reference on what those field inspections actually measure, the technical basis is ANSI/RESNET/ICC 380-2022 for duct leakage and the airflow envelope provisions in 2024 IECC Table R402.4.1.2.
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Call (859) 983-7382 Get a Quote| Service | Typical Project Fee | When It Runs |
|---|---|---|
| Blower door test, single-family under 3,000 sf | $285–$425 per visit | After envelope and duct rough-in are complete |
| Duct leakage to outside, rough-in | $230–$340 per visit | Before drywall, with HVAC fan accessible |
| Combined blower door + duct leakage, single visit | $480–$650 per visit | Coordinated rough-in inspection |
| ENERGY STAR v3.2 field verification | $525–$795 per home | Two-site visit minimum per program rules |
| 45L certification package, ZERH pathway | $950–$1,850 per project | Includes Rater-of-Record sign-off and HERS submission |
| Multifamily whole-building blower door, 20–80 units | $0.18–$0.32 per gross sf | NGBS or ENERGY STAR MFNC qualification |
These figures reflect single-family projects in the Louisville and Lexington metro; rural Kentucky runs 10–15% higher due to drive time. Multifamily and large custom homes land above the table ceiling because of staggered test phases.
HECS scopes blower door and duct leakage work for projects in Kentucky, Indiana, and Ohio on a flat-fee basis, with written caps before mobilization. For a written scope and not-to-exceed letter: (859) 983-7382 or hecsusa.com/contact/.
A blower door number is only useful if the receiving standard tells you what to compare it against. Three standards matter for most 2026 builds in CZ4 Kentucky, the Louisville, Lexington, and Northern Kentucky climate zone.
Under 2024 IECC Table R402.4.1.2, the prescriptive ceiling for a single-family detached home in CZ4 is 2 ACH50 to a Tested-Infiltration Rate or 3 ACH50 when Verified using the default value; HECS field data clusters tight to these prescribed limits. ENERGY STAR v3.2, specifically the Revision 11 (Rev 11) National v3.2 (Rev 11) Single-Family New Construction program, ties blower door to a target plus a Level 1 blower door checklist, not a standalone single number.
For duct leakage, the 2024 IECC default is total leakage of ≤5% of nominal CFM (CFM25 / nominal airflow, multiplied by floor area served, with measurement at 25 Pa) per Table R402.4.2.2. RESNET and ENERGY STAR MFNC reference ANSI/RESNET/ICC 380-2022 for the test method.
ASHRAE 90.1-2022 governs commercial: a baseline envelope typically targets ≤0.40 CFM75 per gross sf, while ASHRAE 62.2-2022 sets the corresponding outdoor airflow rate based on floor area and bedroom count.
The §45L credit is alive for projects that complete certification by December 31, 2032, under the One Big Beautiful Bill Act's extension. The program pays per-unit amounts that depend on which threshold the building clears. For ZERH (net-zero ready) under ENERGY STAR v3.2, the credit is the statutory maximum at the levels below:
| Threshold | Credit Amount | Construction Start Window |
|---|---|---|
| ENERGY STAR v3.0 (legacy) | $2,000 per dwelling unit | Acquired before Jan 1, 2033, placed in service before 2033 |
| ENERGY STAR v3.1 (current baseline) | $2,500 per dwelling unit | Per Rev 11 program rules |
| Zero Energy Ready Home | $5,000 per dwelling unit | ZERH-certified by accredited Rater; placed-in-service before 1/1/2033 |
Per-unit caps scale with apartment counts on multifamily projects, and HECS files the certification package through the HERS provider network so the IRS Form 8908 attachment is accepted by the IRS processing center.
HECS also files FORTIFIED Home and EarthCraft certifications when those are the chosen pathway, substitution cases are common when an insurance carrier offers a premium credit that exceeds the §45L per-unit ceiling.
What is the average blower door test cost in Kentucky for 2026?
HECS invoices for single-family projects in Louisville and Lexington cluster between $285 and $425 per visit in Q1 2026, with combined blower-door-plus-duct packages ranging $480 to $650. Multifamily whole-building tests run on a per-square-foot basis and typically price between $0.18 and $0.32 per gross sf as a separately scoped line.
Does 2024 IECC require 3 ACH50 or less in climate zone 4?
Per 2024 IECC Table R402.4.1.2, a tested CZ4 single-family home must reach ≤2 ACH50 under the Tested-Infiltration Rate option, while the Verified option accepts ≤3 ACH50. ENERGY STAR v3.2 (Rev 11) is anchored to a target index, but contractors commonly benchmark the field test against 3 ACH50 as a working ceiling.
Is §45L still available in 2026, and how much can a builder claim?
Yes. The federal energy-efficient home credit is extended through December 31, 2032, by the One Big Beautiful Bill Act. Per IRC §45L, the credit pays $2,500 per ENERGY STAR-certified unit and $5,000 per Zero Energy Ready Home unit, with multifamily per-unit caps scaling to building size; HECS files the HERS provider packet and the supporting RESNET documentation for transfer to the builder's tax preparer.
HECS schedules blower door, duct leakage, and ENERGY STAR / 45L field inspections across Kentucky, Indiana, Ohio, Tennessee, Illinois, and Missouri. HECS also serves Louisville KY, Lexington KY, Cincinnati OH, Indianapolis IN, Nashville TN, and St. Louis MO as the highest-volume corridors. Field work is performed by NCI-certified technicians; certifications are signed by an accredited Rater of Record and filed through the project HERS provider for §45L submission. Phone (859) 983-7382; email [email protected]. Full services menu at hecsusa.com/services/; service-area map at hecsusa.com/service-area/; direct 45L program page at hecsusa.com/45l-tax-credit-louisville-ky/.
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