The Section 45L energy efficient home credit closes for multifamily on a federal statutory date. Builders across Kentucky, North Carolina, and Alabama must lock certifications now.

Why Section 45L Matters More in 2026 Than Prior Cycles

Section 45L of the Internal Revenue Code provides a per-unit tax credit for developers of energy-efficient multifamily and single-family construction. The credit amount depends on certification to qualifying programs, and the placed-in-service date governs eligibility under the federal statutory window published in IRS guidance. For developers working on lease-up phases in Louisville, Lexington, Cincinnati, and Indianapolis, that window narrows sharply through 2026.

The credit applies to buildings three stories or fewer above grade. Mid-rise projects four stories and above do not qualify for 45L but may pursue the 179D deduction or utility allowance strategies. HECS handles the certification documentation required for 45L; HECS does not prepare or file the developer's tax return, which falls to a CPA or tax counsel.

Documentation required at placed-in-service includes the certification from a HERS Rater or approved verifier, energy modeling per RESNET standards, and field verification of envelope and duct leakage. The IRS requires the certification be in place before the placed-in-service date — retroactive certification is not permitted under current IRS guidance.

What HECS Verifies in the Field

For 45L submissions on multifamily projects, HECS performs blower door testing, duct leakage testing, and visual inspection of insulation and air sealing details per the program requirements. RESNET standards govern the test protocols, including multi-family low-rise sampling procedures for projects with 25 or more units per RESNET MINERS protocols as applicable.

Working with HECS: HECS performs FORTIFIED Roof Evaluation for multifamily and single-family projects across Kentucky, North Carolina, Alabama, Georgia, West Virginia, Kansas, and Missouri. Documentation is delivered in a format compatible with CPA submission packages. For a scope call: (859) 983-7382 or hecsusa.com/contact/.

Field Test Thresholds

Program thresholds vary by climate zone and revision. HECS project data shows typical envelope leakage rates in the 3-5 ACH50 range for ENERGY STAR multifamily projects in Climate Zone 4A, and tighter for Net Zero or ZERH pathways. Final thresholds must match the program version cited on the developer's certification documentation. The current ENERGY STAR Multifamily New Construction revision governs eligible thresholds; HECS confirms which revision applies to each project's placed-in-service date.

Duct Leakage Verification

Duct leakage to outside is verified per RESNET standards. For multifamily, ducts located entirely within conditioned space often achieve compliance through visual inspection rather than pressure testing. Ducts in unconditioned attics or chases must be tested and documented.

Coordinating 45L With Other Certifications

Many Kentucky developers stack 45L certification with ENERGY STAR Multifamily, NGBS-2023, or EarthCraft certification. Each program has independent verification requirements, but RESNET-certified HERS Raters can deliver overlapping documentation across programs. HECS holds the certifications required to verify under multiple programs concurrently.

Certification Stack Comparison

A typical Louisville garden-style project pursuing 45L plus ENERGY STAR will require blower door testing on a sampling basis per the current ENERGY STAR Multifamily New Construction sampling protocol, duct leakage testing on units with exterior duct runs, and final inspection by the RESNET-certified provider.

Common Pitfalls on 45L Submissions

Three failures recur on HECS project reviews. First, developers initiate the certification process too late, after framing and insulation are enclosed and corrections are costly. Second, the HERS Rater's sampling protocol is not confirmed before construction begins, leading to inadequate documentation for the unit count. Third, the ENERGY STAR program version is not locked at design phase, creating a mismatch between design targets and final field results.

HECS coordinates pre-drywall inspections, mid-construction verification, and final testing on a single mobilization schedule. This avoids the rework that occurs when envelope deficiencies are identified only after drywall closure. See hecsusa.com/45l-tax-credit-louisville-ky/ for service details specific to Louisville multifamily projects.

What Kentucky Developers Should Confirm This Quarter

The 2026 statutory deadline places a hard cap on placed-in-service dates. Developers should confirm three items: the project placed-in-service date per the building permit and occupancy schedule, the ENERGY STAR MFNC program version applicable to that date per current ENERGY STAR guidance, and whether NGBS-2023 or EarthCraft certification provides a more efficient pathway for the specific unit mix and climate zone.

For projects breaking ground in mid-2026 with lease-up in 2027, the statutory window may close before completion. Developers should consult tax counsel and engage a HERS Rater early in design. HECS offers preliminary project reviews to confirm eligibility before contract execution.

ASHRAE 62.1 compliance is referenced in some 45L pathways; confirm with the project's energy modeler which code edition applies to the county in which the building is located. Kentucky's commercial energy code adoption varies by jurisdiction. The Residential Code adoption status also varies, and the 2024 IECC may apply in jurisdictions that have adopted the current edition.

—

Frequently Asked Questions

Does 45L apply to garden-style apartments in Lexington?

Yes, if the building is three stories or fewer above grade. Four-story and taller mid-rise projects do not qualify for 45L but may pursue alternative federal incentives. HECS verifies per the current program documentation and coordinates with the developer's tax counsel on eligibility confirmation.

Can NGBS-2023 certification substitute for ENERGY STAR on 45L submissions?

In many cases, yes. IRS guidance permits certain accredited certification programs to qualify units for 45L. HECS holds NGBS Green Certified Verifier credentials and can deliver certification documentation for either pathway. Confirm the specific program version accepted under current IRS guidance with the developer's CPA.

What happens if a unit fails the blower door test after drywall?

Remediation is costly because air sealing details are concealed. HECS recommends pre-drywall blower door testing on a sample basis per RESNET standards, then final testing at completion. This two-stage approach identifies envelope deficiencies while corrections remain feasible.

—

How to Engage HECS

HECS provides FORTIFIED Roof Evaluation, ENERGY STAR Multifamily Certification, NGBS-2023 Green Certification, EarthCraft Certification, blower door testing, and duct leakage testing for multifamily developers across Kentucky, North Carolina, Alabama, Georgia, West Virginia, Kansas, and Missouri. To scope a project, contact HECS at (859) 983-7382 or [email protected]. Service details are available at hecsusa.com/services/ and project intake at hecsusa.com/contact/. HECS serves Louisville KY, Lexington KY, Cincinnati OH, Indianapolis IN, Nashville TN, Evansville IN, and St. Louis MO, with mobilization to additional markets upon request.