Commercial rooftop units — the workhorses of American commercial HVAC — face their most significant efficiency update in over a decade. DOE's direct final rule, published May 20, 2024, and confirmed effective September 17, 2024, establishes amended energy conservation standards for air-cooled commercial package air conditioners and heat pumps with compliance required on and after January 1, 2029 (DOE).
What changes on January 1, 2029
The amended standards align with recommendations from a DOE-sponsored stakeholder working group that included manufacturers, efficiency advocates, and electric utilities. DOE projects 5.5 quadrillion Btu in energy savings over 30 years of shipments — a 10% reduction relative to products currently on the market — along with nearly $24 billion in consumer utility-bill savings and 109 million metric tons of CO2 reductions, equivalent to the annual emissions of 14.2 million homes (DOE).
Energy-use reductions vary by equipment size: small equipment (65,000-135,000 Btu/hr) sees the largest improvement at 23%, large equipment (135,000-240,000 Btu/hr) at 11%, and very large equipment (240,000-760,000 Btu/hr) at 8% (Appliance Standards Project).
Current standards vs. what is on the market
| Metric | Current Tier 2 (since 2023) | Best on Market | 2029 Standard |
|---|---|---|---|
| Minimum IEER (cooling) | 12.3-14.8 (varies by size) | Up to 26 | IVEC metric (TBD levels) |
| Minimum COP (heating, HP) | 3.2-3.4 | Up to 4.0+ | IVHE metric (TBD levels) |
| Energy-use reduction vs. current | — | — | 8-23% by size category |
| Compliance date | Jan 1, 2023 | — | Jan 1, 2029 |
| Next DOE review | — | — | 2030 |
New metrics: IVEC and IVHE
The 2029 standards introduce two new efficiency metrics that fundamentally change how commercial rooftop performance is measured. Integrated Ventilation, Economizing, and Cooling (IVEC) replaces IEER for cooling efficiency, and Integrated Ventilation and Heating Efficiency (IVHE) replaces COP for heating. The new metrics reflect seasonal efficiency and capture fan energy use and economizer operation — two factors IEER ignored. Testing to IVEC and IVHE became mandatory for manufacturers starting May 15, 2025, though compliance with standards based on those metrics is not required until 2029 (DOE).
IEER, the current metric, is a weighted calculation of mechanical cooling efficiency at 100%, 75%, 50%, and 25% load — but it measures only compressor and condenser energy, not fan energy. A unit with an efficient compressor but an oversized supply fan could score well on IEER while wasting energy in real operation. IVEC closes that gap (Appliance Standards Project).
ASHRAE 90.1 restructures for 2028.On July 16, 2026, ASHRAE announced a strategic direction for Standard 90.1: the 2025 edition's optional operational-carbon Addenda M and N will move out of the core standard into a separate, dedicated publication. Standard 90.1 will refocus on energy efficiency and energy-cost-justified requirements, while the companion document handles operational GHG emissions and renewable-energy accounting. The Standing Standard Project Committee's six-year work plan covers 2028 and 2031 cycles, drawing on 153 committee members (ASHRAE).
Federal buildings lead the way
Federal buildings face even stricter requirements. Under 10 CFR 433, new federal commercial buildings must meet ASHRAE Standard 90.1-2019 and achieve energy consumption at least 30% below the codified federal standard where life-cycle cost-effective. Additionally, the Federal Clean Energy Rule requires new federal construction and major renovations to reduce on-site fossil fuel consumption by 90% for projects in FY 2025-2029 and 100% for FY 2030 and later (DOE FEMP).
What this means for building owners and contractors
- Equipment planning: Units purchased before 2029 can be installed under current standards, but specifiers should evaluate lifetime operating costs against the 2029 baseline.
- IEER vs. IVEC: When comparing units, remember that IEER does not capture fan energy. Two units with identical IEER can have very different real-world energy use.
- Economizer functionality: IVEC rewards proper economizer operation — ensure economizers are functional and calibrated, not locked out.
- Energy Efficiency Reform Act: If passed, the Senate bill introduced in August 2026 would eliminate the mandatory six-year review cycle and could delay future standard updates beyond the 2030 review.
- ASHRAE 90.1 split: Building performance standards (BPS) and carbon reporting requirements will increasingly reference the new companion publication, not 90.1 itself.
Naming a product or manufacturer in this article is for identification purposes only and does not constitute an endorsement by HVAC Zone Inc. We are a multi-brand dealer and remain neutral on brand preference.
Planning a commercial equipment replacement or new construction? Request a consultation — we evaluate equipment against both current and upcoming standards to protect your investment.