EarthCraft and NGBS overlap on envelope testing but diverge on energy compliance, sampling, and third-party roles. Here's how to decide for Kentucky, Tennessee, and the lower Midwest.
Southeast builders regularly ask whether EarthCraft or NGBS Green is the right fit for a garden-style apartment, a townhome development, or a senior living project. The two programs are both ANSI-accredited, both have NGBS Green Certified Verifier and EarthCraft Certified Verifier credentials behind them, and both reward air-sealing and duct tightness — yet they enforce those rewards through different mechanics.
EarthCraft is a regional program administered through the Greater Atlanta Home Builders Association ecosystem and partners, oriented to multifamily and single-family light commercial across the Southeast. NGBS is administered by Home Innovation Research Labs and applies nationally, with ANSI / ICC / ASHRAE 700-2023 as its reference standard. Both require third-party verification, but the verifier credentials and sampling protocols diverge in ways that matter on bid day and at certificate issuance.
The frequent mistake is assuming one program is "looser" than the other. EarthCraft Multifamily and NGBS Bronze, Silver, Gold, and Emerald tiers are all performance-based — tier elevation depends on points accumulated, not a single pass/fail checkbox. Builders who pick a tier without mapping it to a binding code path (2024 IECC, ENERGY STAR MFNC, or the IRC §45L tax credit path) often end up re-doing documentation at rough-in.
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Call (859) 983-7382 Get a QuoteNGBS-2023 (ANSI / ICC / ASHRAE 700-2023) Chapter 7 addresses resource efficiency including air leakage, blower door, and duct leakage requirements. NGBS §903 cites ASHRAE 62.2-2022 for ventilation. EarthCraft references ASHRAE 90.1-2019 as the energy baseline in its multifamily track, with required functional testing that overlaps — but is not identical to — the ENERGY STAR MFNC National Program Requirements Version 1.3 (Rev05), January 2025 HVAC Functional Testing Checklist.
For Kentucky and Indiana projects specifically, 2024 IECC Table R402.4.1.1 sets the binding blower door limit at 3.0 ACH50 for Climate Zones 4A and 5A — not 5.0 ACH50. Louisville (Jefferson County) and most of Indiana fall in CZ 4A; northeastern counties (Boyd, Carter, Greenup in KY; Allen, DeKalb, Noble in IN) sit in CZ 5A. Either way, the envelope is held to the tighter side of the table. NGBS Bronze aligns with this threshold; NGBS Silver, Gold, and Emerald tighten it further. EarthCraft's envelope metrics align with these same code floors but are not a substitute for IECC compliance — both can run in parallel.
Duct tightness thresholds also matter. 2024 IECC R403.3.5 requires verified total leakage to outside ≤ 4 CFM25 per 100 ft² of conditioned floor area for ducts in unconditioned space. NGBS-2023 §704.1 references ANSI/RESNET/ICC 850 for duct leakage testing. ENERGY STAR MFNC v1.3 Rev05 layers additional thresholds: ≤ 6 CFM25 per 100 ft² at rough-in, ≤ 8 CFM25 post-construction. A project targeting all three must meet the tightest applicable number, not the loosest.
NGBS §702.1.1 mandates third-party verification at all certification tiers. §702.1.1.1 lists acceptable verifier credentials — NGBS Green Certified Verifier, RESNET Certified HERS Rater, BPI Building Analyst, or equivalent as approved by Home Innovation Research Labs. Specific compliance pathways may require RESNET/HERS credentials even when NGBS verification is present, so credentialing is pathway-dependent, not tier-dependent.
EarthCraft requires an EarthCraft Certified Verifier — a separate credential issued through its regional training pipeline. HECS holds both EarthCraft and NGBS Green Certified Verifier credentials, so a project can pivot between programs without changing verifier mid-stream.
HECS handles EarthCraft verification and NGBS Green verification for projects in Kentucky, Indiana, Ohio, Tennessee, Illinois, and Missouri. For a scope call on a multifamily or townhome development targeting either program: (859) 983-7382 or hecsusa.com/contact/. See the full verification service list at hecsusa.com/services/.
HECS treats EarthCraft and NGBS as parallel verification tracks rather than competing choices. The pre-construction scope call identifies the code path (2024 IECC prescriptive, 2024 IECC simulated performance per R405, or ASHRAE 90.1-2019), the certification target (EarthCraft Multifamily tier or NGBS Bronze through Emerald), and any tax-credit pathway — IRC §45L homes acquired on or before 2026-06-30 can stack $2,500 base plus $1,000 prevailing-wage bonus per qualifying unit.
For multifamily projects, HECS builds the sampling protocol into the bid. ANSI/RESNET/ICC 380 governs HERS sampling; Table R405.4.2(1) governs IECC blower door sampling for multi-family. NGBS allows verifier-directed sampling at lower tiers; EarthCraft Multifamily uses its own sampling matrix. Getting sample size wrong — too few units tested, or wrong unit selection — is one of the most common reasons certificates stall.
HECS is NCI-certified for air balancing (NCI Commercial Air Balancer and NCI Residential Air Balancer), so the same technician who verifies envelope tightness also confirms HVAC airflow at design CFM. That dual role eliminates the handoff gap between envelope and mechanical trades that often surfaces at functional testing.
The EarthCraft and NGBS verification reports are different documents but share a common backbone. Both include:
Reports carry verifier signature, credential number, and a project-specific compliance summary that can be handed to code officials, lenders, or the 45L certification reviewer without rework.
Does EarthCraft Multifamily satisfy 2024 IECC on its own? No. EarthCraft aligns with IECC thresholds but does not replace the IECC compliance certificate. A project pursuing EarthCraft in Kentucky or Tennessee still needs the local code official to accept the IECC R402.4.1.2 blower door result and the R403.3.5 duct tightness result independently. HECS sequences both verifications in a single site visit where the program allows.
Can a project stack NGBS Gold with the IRC §45L tax credit? Potentially, but the §45L energy threshold (ENERGY STAR certified or DOE Zero Energy Ready Home equivalent, plus prevailing-wage documentation) is separate from NGBS tiering. Homes acquired after 2026-06-30 do not qualify under current statute. HECS scopes §45L eligibility against the actual closing date and the certification basis before construction starts.
Which program does HECS recommend for a Southeast garden-style project under 50 units? It depends on the target market and lender requirements. For projects where FHA financing or HUD Handbook 4350.3 documentation will be required, NGBS Green is often the cleaner path because of its national ANSI anchor. For projects seeking regional recognition or EarthCraft Multifamily incentives, EarthCraft may carry more weight with the local HBA. HECS runs the cost-and-schedule comparison during the scope call.
HECS provides EarthCraft verification, NGBS Green verification, ENERGY STAR MFNC functional testing, blower door testing, duct leakage testing, and §45L tax credit certification for multifamily and townhome projects across Kentucky, Indiana, Ohio, Tennessee, Illinois, and Missouri. Contact (859) 983-7382 or [email protected] to start a scope conversation, or submit a project at hecsusa.com/contact/. Service details at hecsusa.com/services/. HECS also serves Louisville KY, Lexington KY, Cincinnati OH, Indianapolis IN, Nashville TN, and Evansville IN for in-person scoping. For EarthCraft projects specifically, see hecsusa.com/earthcraft/.
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