Reference
HVAC Efficiency Ratings Table
Every efficiency rating on heating, cooling and water heating equipment, what it measures, how the 2023 test change moved it, and how to turn it into energy use.
The ratings
| Rating | Equipment | Definition | Typical new range |
|---|---|---|---|
| SEER2 | Central AC and heat pumps, cooling | Seasonal cooling output in BTU ÷ electricity in watt-hours, M1 test | 13.4 to 22+ |
| EER2 | Central AC and heat pumps, cooling | Cooling in BTU/hr ÷ watts at 95 °F outdoors | 10 to 14 |
| HSPF2 | Heat pumps, heating | Seasonal heating in BTU ÷ watt-hours | 7.5 to 10+ |
| COP | Heat pumps, any heater | Heat delivered ÷ energy used, same units | 2 to 4.5 for heat pumps; 1 for resistance |
| CEER | Room air conditioners | Combined energy efficiency ratio, BTU/hr per watt including standby | 10 to 12 typical |
| SACC | Portable air conditioners | Seasonally adjusted cooling capacity, BTU/hr | 55% (single hose) to 65% (dual hose) of ASHRAE label |
| AFUE | Gas, propane and oil furnaces and boilers | Annual useful heat ÷ fuel energy | 80% to 98.5% |
| UEF | Water heaters | Hot-water energy ÷ energy used over a standard test day | 0.6 to 4 |
| IEF | Dehumidifiers | Litres of water removed per kWh, 2019 test | About 1.9 typical |
Conversions
| From | To | Factor |
|---|---|---|
| SEER (before 2023) | SEER2 | × 0.95 |
| HSPF (before 2023) | HSPF2 | × 0.85 |
| HSPF2 | Seasonal COP | ÷ 3.412 |
| SEER2 | EER2 (approximate) | × 0.875 |
| EER | COP | ÷ 3.412 |
The 2023 change raised the external static pressure in the test from 0.1 to 0.5 inches of water column, closer to real ducts, so the same equipment scores lower.
Federal minimums
| Equipment | Region | Minimum since 2023 |
|---|---|---|
| Split central air conditioner | North | 13.4 SEER2 |
| Split central air conditioner | Southeast and Southwest | 14.3 SEER2 (under 45,000 BTU/hr) |
| Split central air conditioner | Southwest | plus an EER2 minimum |
| Split heat pump | National | 14.3 SEER2, 7.5 HSPF2 |
| Non-weatherized gas furnace | National | 80% AFUE |
From a rating to energy use
AC power while running (kW) = capacity (BTU/hr) ÷ (SEER2 × 1,000)
cooling season (kWh) = tons × 12,000 × full-load hours ÷ (SEER2 × 1,000)
heat pump power (kW) = heat output ÷ (COP × 3,412)
furnace fuel (BTU/hr) = heat output ÷ AFUE
saving from an upgrade = old cost × (1 − old rating ÷ new rating)
Worked figures from the calculators:
- A 3-ton unit at SEER2 15 draws 2.4 kW; 8 hours a day for 30 days at 17 cents is 576 kWh and $97.92.
- SEER 10 (SEER2 9.5) to SEER2 15.2, 3 tons, 1,200 full-load hours, 17 cents: saves $289.89 a year.
- An 80% furnace to a 96% one on a $1,400 bill: saves $233 a year.
- HSPF2 8.5 is a seasonal COP of 2.49; delivering 30,000 BTU/hr draws 3.53 kW.
Default efficiencies the calculators use
Gas and propane furnaces 95% AFUE, oil 85%, heat pump seasonal COP 2.8, pellet stoves 80%, wood stoves 70%, electric resistance 100%. Water heaters: gas tank UEF 0.65, electric tank and tankless 0.93, heat pump water heater 3.5. Every one can be replaced with the figure on your own equipment.
Calculators that use these ratings
- Cooling: SEER upgrade savings, AC running cost, tonnage converter
- Heating: furnace size, heat pump size, boiler size
- Airflow: equivalent length
- Costs: HVAC running cost, upgrade payback, cost per million BTU
- Installation: replacement cost, furnace install cost, heat pump install cost, mini-split install cost, AC repair cost, maintenance cost
- Water heating: tank size, tankless size, running cost, recovery time, replacement cost
- Planning: size check, lifespan planner, generator size
The guide to SEER2, HSPF2, AFUE and COP explains the ratings in more detail.