SEER2 replaced SEER in January 2023. The ASHRAE 90.1-2022 standard is now the basis for commercial energy codes in most jurisdictions. The 2024 International Energy Conservation Code is being adopted by states on rolling schedules. If you are still thinking about any of these as future changes, you are behind.

For HVAC contractors, energy code compliance is not an academic concern — it is a direct liability. Installing non-compliant equipment, failing to follow code-required duct sealing procedures, or misunderstanding the regional efficiency minimums that apply to your market can result in failed inspections, customer complaints, and potential legal exposure. This is the plain-English guide to where the codes actually stand in 2026.

What Is SEER2 and How Does It Differ From SEER?

SEER — Seasonal Energy Efficiency Ratio — was the efficiency metric used for residential air conditioning and heat pump equipment from 1992 through 2022. SEER2 replaced it effective January 1, 2023, using an updated test procedure that applies 5 pascals of external static pressure to the indoor unit — closer to what equipment actually experiences in the field — rather than the near-zero static pressure used in SEER testing.

The practical effect of the SEER2 test procedure is that the same physical equipment scores approximately 5% lower under SEER2 than under SEER. A unit that rated SEER 14 under the old test procedure rates approximately SEER2 13.4 under the new procedure. This means that the SEER2 minimum efficiency requirements, while numerically lower than the old SEER minimums they replaced, actually represent similar or slightly higher actual equipment efficiency.

SEER2 replaced SEER as the residential air conditioning efficiency metric effective January 1, 2023, using a more realistic test procedure that applies 5 pascals of external static pressure to the indoor unit. Equipment that previously rated SEER 14 typically rates approximately SEER2 13.4 under the new test procedure.

The Regional Efficiency Minimum Map

One of the most important and most misunderstood aspects of SEER2 is its regional structure. Unlike the previous SEER regime which had a single national minimum (with some regional variation), SEER2 divides the US into three regions with different minimum efficiency requirements:

• North Region (defined as states where less than 50% of housing units have central air conditioning, or where all of Alaska): Minimum SEER2 of 13.4 for split system central air conditioners. This covers most of the northern US including the upper Midwest, New England, and Pacific Northwest.

• South Region (defined as remaining continental US states not in the North Region): Minimum SEER2 of 14.3 for split system central air conditioners.

• Southwest Region (Arizona, California, Nevada, and New Mexico): Minimum SEER2 of 14.3 for split systems, with additional requirements for heat pumps.

For heat pumps, the minimum SEER2 is 14.3 nationwide for split systems, with regional HSPF2 (heating) minimums varying by region. The regional map is publicly available at the DOE Energy Efficiency and Renewable Energy website and should be referenced directly when specifying equipment for any project.

Contractors who operate near state borders — or who serve customers who do — need to know which region applies to their specific installation location, not just to their home base. The regional minimum that applies is the one for the installation location, not the contractor's office location.

ASHRAE 90.1-2022: What Changed for Commercial HVAC

ASHRAE Standard 90.1 is the energy efficiency standard for commercial buildings — everything from small retail to hospitals to high-rise office buildings. The 2022 edition of 90.1 is now the reference standard for commercial energy codes in most US jurisdictions, having been adopted by the model codes (IECC commercial) and many states directly.

Key changes in ASHRAE 90.1-2022 that affect HVAC contractors working in commercial applications:

• Minimum efficiency increases: Minimum efficiency requirements for commercial unitary equipment, chillers, and packaged terminal equipment have been updated upward. Contractors who are specifying commercial equipment should verify that the models they are proposing meet 90.1-2022 minimums for the equipment category and cooling capacity.

• Demand-controlled ventilation expansion: 90.1-2022 expands the occupancy density and space type requirements that trigger mandatory DCV (demand-controlled ventilation). More commercial spaces now require CO2-based ventilation control than under prior versions of the standard.

• Energy recovery requirements: Minimum ventilation air energy recovery requirements have been expanded in 90.1-2022. HVAC designers specifying air handling systems in climate zones where energy recovery is now mandatory need to include compliant energy recovery devices — typically heat recovery ventilators or energy recovery ventilators.

• Commissioning requirements: 90.1-2022 strengthens requirements for HVAC system commissioning, including functional performance testing and documentation. Contractors on commercial projects in jurisdictions using 90.1-2022 need to be prepared for more rigorous commissioning requirements.

IECC 2024 Envelope Design Changes

The 2024 International Energy Conservation Code includes provisions that affect the building envelope and therefore interact with HVAC system sizing. The most relevant changes for HVAC contractors:

• Tighter infiltration requirements: The 2024 IECC tightens whole-building air leakage requirements in most climate zones. Tighter envelopes mean lower heating and cooling loads — and therefore smaller properly-sized HVAC systems. Contractors who have been sizing equipment based on older assumptions about envelope performance may need to revisit their Manual J methodology for new construction projects in jurisdictions adopting the 2024 IECC.

• Increased insulation requirements: Additional insulation requirements in the 2024 IECC further reduce envelope heat gain and loss. Combined with tighter infiltration requirements, new homes built to 2024 IECC standards may require meaningfully smaller HVAC systems than equivalent homes built to older codes.

For contractors, the practical implication is straightforward: always perform a Manual J load calculation for new construction rather than rule-of-thumb sizing, and ensure your load calculation inputs reflect the actual code requirements for the jurisdiction and code cycle in which you are working.

How to Stay Compliant in 2026

Compliance steps every contractor should have in place:

• Know your jurisdiction's adopted code version: States and localities adopt codes on different schedules. Your state may be on the 2021 IECC while a neighbouring state is adopting the 2024 IECC. The BCAP (Building Codes Assistance Project) maintains a current state-by-state code adoption database at bcapcodes.org.

• Verify equipment compliance at the point of specification: Do not assume that a product in your distributor's catalogue meets current minimum efficiency requirements. Check the DOE's Compliance Certification Management System (CCMS) database for the specific model and configuration you are installing.

• Document your work: Retain copies of equipment efficiency certificates, duct leakage test results, and commissioning documentation for every project. If a jurisdiction later questions compliance, documentation is your protection.

• Keep your training current: ACCA's Manual J and Manual S training, updated for SEER2 and current code versions, is available through ACCA's online platform and through approved training providers. Code compliance is a moving target — annual training updates are not optional for contractors who want to stay current.

Frequently Asked Questions

What is the minimum SEER2 rating in 2026?

Minimum SEER2 requirements vary by region. In the North Region, the minimum is SEER2 13.4 for split system central air conditioners. In the South and Southwest Regions, the minimum is SEER2 14.3. For heat pumps, the minimum is SEER2 14.3 nationwide for split systems, with regional HSPF2 heating minimums.

What replaced SEER in HVAC efficiency ratings?

SEER2 replaced SEER as the primary residential air conditioning and heat pump efficiency metric effective January 1, 2023. SEER2 uses a more realistic test procedure applying 5 pascals of external static pressure, resulting in ratings approximately 5% lower than the equivalent equipment's SEER rating under the old test procedure.

What is ASHRAE 90.1-2022 and does it affect HVAC contractors?

ASHRAE 90.1-2022 is the energy efficiency standard for commercial buildings, now serving as the basis for commercial energy codes in most US jurisdictions. It affects HVAC contractors through updated minimum equipment efficiency requirements, expanded demand-controlled ventilation mandates, new energy recovery requirements, and strengthened commissioning documentation standards.

How do I find out which energy code applies to my HVAC installation?

Energy code adoption varies by state and locality. The Building Codes Assistance Project (bcapcodes.org) maintains a current state-by-state energy code adoption database. Always verify the applicable code version with the local authority having jurisdiction (AHJ) before beginning a project.

What happens if I install non-compliant HVAC equipment?

Installing equipment that does not meet minimum efficiency requirements for the applicable jurisdiction can result in failed inspections, required equipment replacement, contractor liability, and potential warranty complications. In jurisdictions with DOE enforcement authority, non-compliant equipment installation can result in fines and enforcement action.