A field-side guide to certification level selection, air sealing targets, and documentation burden across Kentucky, Indiana, and Ohio multifamily projects.
The NGBS Green Certified program, administered under the National Green Building Standard (NGBS-2023), structures multifamily achievement across Bronze, Silver, Gold, and Emerald levels. Builder decisions made at schematic design lock in air leakage, duct leakage, and HERS targets that determine whether a project comfortably clears its tier or fights the threshold at final inspection.
For developers across our service region, the tier is rarely a pure cost decision. Lenders, state housing finance agencies, and utility program operators frequently reference NGBS tier thresholds when sizing incentives or underwriting affordability deals. Selecting the wrong tier mid-design can mean field re-work after drywall is up, or a project that technically certifies but loses its positioning in a competitive funding round.
At every tier, NGBS-2023 requires third-party verification of energy, water, and indoor air quality performance. HECS performs the HVAC Testing & Balancing work, duct leakage testing, blower door testing, and radon sampling that populate the verifier's submittal package. The verifier, HECS in our case, independently confirms each performance criterion before certification is awarded.
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Call (859) 983-7382 Get a QuoteThe NGBS-2023 point structure rewards cumulative performance across energy efficiency, water conservation, indoor environmental quality, and site/operations categories. In HECS project data, the practical difference between Bronze and Emerald shows up in three places: envelope airtightness, duct leakage to outside, and overall HERS score.
Based on HECS project data across Kentucky and Indiana multifamily projects, builders targeting Bronze typically deliver envelopes in a mid-single-digit ACH50 range. Silver-class projects in our region typically push tighter. Gold and Emerald projects compress the band further. We describe these as ranges because final numbers depend on unit count, stack effect, and whether the building is slab-on-grade or elevated, variables the verifier evaluates project by project.
Duct leakage to outside is tested per ACCA Manual D and ANSI/ACCA standards for system design, with the to-outside CFM25 figure trending lower as tier rises. In our experience, Bronze projects typically clear the program floor with moderate attention to mastic and boot sealing. Silver projects require systematic verification at rough-in. Gold and Emerald demand third-party witnessed testing with documentation that satisfies the verifier's review.
NGBS-2023 references HERS scoring per RESNET standards. In HECS project data, Bronze-tier projects commonly land in a moderate HERS band, with progressively lower index scores as tier rises. Emerald projects in our region typically require aggressive envelope and mechanical efficiency combinations to reach the program's upper tier, though the precise index threshold is set by the standard and confirmed by the verifier.
| Tier | Typical Air Tightness (HECS data) | Typical HERS Range (HECS data) | Verifier Burden |
|---|---|---|---|
| Bronze | Mid-single-digit ACH50 | Moderate | Standard |
| Silver | Typically tighter | Lower than Bronze | Moderate |
| Gold | Significantly tightened | Typically compressed band | Heavy documentation |
| Emerald | Field-leading | Typically the lowest band | Witnessed + retest |
The table is directional, not a substitute for reading the standard. Final thresholds come from NGBS-2023 and the verifier's confirmation.
HECS handles NGBS Green Certification for projects in Kentucky, Indiana, Ohio, Tennessee, Illinois, and Missouri. Our scope covers blower door testing, duct leakage to outside, HVAC test and balance, radon sampling, and the final verifier sign-off package. For a scope call: (859) 983-7382 or hecsusa.com/contact/.
The most common failure mode in our region is the rough-in duct leakage test. Crews seal the visible boots and trunks, but the chase walls and platform returns carry leakage that doesn't show until the duct pressurization test runs at 25 Pa. By that point, drywall is often staged. Rework cost rises sharply.
The second recurring issue is bathroom and kitchen exhaust compliance per ASHRAE 62.2-2022. Multifamily projects often specify the right fans on paper but fail runtime or sound requirements in the field. HECS measures airflow at the grille and decibel readings at the door to confirm compliance with the standard's local exhaust requirements.
Third, the HERS index path can drift between the rated design and the as-built home. Insulation substitutions, window U-factor changes, and HVAC equipment swaps during construction all move the index. Verifiers reconcile rated versus as-built; large gaps can pull the project below its tier threshold.
The NGBS Green Certified verifier package is not a marketing binder. It is a structured set of test results, photo logs, and material confirmations mapped to specific practice points in the standard. HECS submits:
The verifier reviews these against the project's scored checklist and either approves or flags. Flagged items get a corrective action window; the project doesn't certify until the flags close.
Does NGBS 2023 require blower door testing on every multifamily unit?
Yes. Individual unit blower door testing is required for multifamily projects seeking certification above the entry tier, and sample-based testing protocols apply for larger buildings per NGBS-2023. HECS scopes the sample size based on project size and tier target. Results feed directly into the verifier's airtightness confirmation.
Can a project move from Bronze to Silver after construction starts?
It can, but the airtightness and HERS targets shift enough that the rough-in and final testing protocols change. In our experience, mid-construction tier upgrades usually mean re-running the HERS index from the as-built model and confirming the new airtightness band is achievable with the envelope already in place. Early planning is cheaper than late pivots.
How does NGBS interact with ENERGY STAR Multifamily New Construction?
The two programs reference common test protocols, and projects can pursue both. ENERGY STAR Multifamily New Construction follows its own v3.1 (and v3.2 where applicable) certification path. HECS coordinates the test sequencing so the same blower door, duct leakage, and TAB work supports both submittals without redundant site visits.
HECS scopes NGBS verification, blower door, duct leakage, HVAC test and balance, and radon sampling 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, Evansville IN, Columbus OH, and Chicago IL. Reach us at (859) 983-7382 or [email protected]. Visit hecsusa.com/services/ for the full service list or hecsusa.com/contact/ to request a proposal. We staff each job with NCI-certified technicians and submit documentation in the format each verifier requires.
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