Central Air Conditioners and Heat Pumps


Residential central air conditioners (CACs) and heat pumps (HPs) (<65,000 Btu/hr) can be ducted or non-ducted (ductless). Most CAC systems are “split systems,” where the condensing unit is typically placed outdoors while the evaporator is indoors. There are also packaged units, which include all of the components as part of a single package and which are often placed on rooftops. 

Residential CACs and heat pumps also include the smaller categories of single-phase space-constrained products and small-duct, high-velocity (SDHV) products.


The current standards for CACs and HPs took effect on January 1, 2023. The standards were based on a consensus agreement between manufacturers and efficiency advocates. The standards for split systems include a regional component, with the SEER2 more stringent for split-system CACs installed in the south than in the north (Table 1). Split-system and packaged CACs installed in the southwest have an additional standard for EER2. Heat pumps have a uniform national standard for heating and cooling modes (Table 2). For CACs and heat pumps that are packaged units, the standards are also uniform nationally. The standards for space-constrained and SDHV products are uniform nationally (Table 3), and are equivalent in stringency to the previous standards.

Table 1. Central AC requirements
SEER213.4Split-system:14.3 (<45kBTU) and 13.8 (≥45 kBTU) Packaged:13.4Split-system:14.3 (<45kBTU) and 13.8 (≥45 kBTU) Packaged:13.4
EER2  Split-system:11.7 (<45kBTU) and 11.2 (≥45 kBTU); if SEER2>15.2, EER2 9.8 Packaged:10.6
For compliance with the regional standards, the southeast includes: Alabama, Arkansas, Delaware, Florida, Georgia, Hawaii, Kentucky, Louisiana, Maryland, Mississippi, North Carolina, Oklahoma, South Carolina, Tennessee, Texas, Virginia, the District of Columbia, and the U.S. territories. The southwest includes: Arizona, California, Nevada, and New Mexico. The north includes: the remainder of the U.S. Table 2. Central heat pump requirements
SEER2Split-system: 14.3 Packaged: 13.4
HSPF2Split-system: 7.5 Packaged: 6.7
 Table 3. Space-constrained and SDHV requirements
SEER2Space-constrained CAC: 11.7 Space-constrained heat pump: 11.9 SDHV CAC and heat pump: 12.0
HSPF2Space-constrained heat pump: 6.3 SDHV heat pump: 6.1

**The cooling energy efficiency metric, seasonal energy efficiency ratio 2 (SEER2) is the total space cooling required during the cooling season, expressed in Btu, divided by the total electrical energy consumed by the air conditioner or heat pump system during the same season, expressed in watt-hours.

The additional cooling energy efficiency metric that applies in the southwest, energy efficiency ratio 2 (EER2), measures full-load efficiency at a 95 °F ambient outdoor air temperature. 

The heating energy efficiency metric, heating seasonal performance factor 2 (HSPF2) is the total space heating required during the heating season, expressed in Btu, divided by the total electrical energy consumed by the heat pump system during the same season, expressed in watt-hours.


The new metrics (SEER2, EER2, and HSPF2) better capture fan energy consumption and the use of electric resistance heating in heating mode compared to the older SEER, EER, and HSPF metrics.

CACs and HPs are rated by their cooling capacity (in Btu/hr), which represents the amount of heat that an air conditioner or heat pump can remove from an enclosed space per hour. One “ton” of cooling capacity is equal to 12,000 Btu/hr. Compared to older units, products meeting the latest standards generally incorporate improved compressors and expansion valves and better and larger heat exchangers.
Savings through what year?: 2052
Energy saved (quads): 3.2
CO2 savings (million metric tons): 188
Net present value savings ($billion) 3% discount rate: 12.2
Net present value savings ($billion) 7% discount rate: 2.5


Fact Sheets


ASAP Press Releases


Standards in the News


Federal Date States
Potential Effective Date of Updated Standard 2030
Updated DOE Standard Due 2025
4th Federal Standard Effective 2023
Potential Effective Date of Updated Standard 2022
4th Federal Standard Adopted (DOE) 2017
Updated DOE Standard Due 2017
Test Procedure - Last Revised - Active Mode 2016
3rd Federal Standard Effective 2015
3rd Federal Standard Adopted (DOE) 2011
Test Procedure - Last Revised - Active Mode 2008
2nd Federal Standard Effective 2006
2nd Federal Standard Adopted (DOE) 2001
1st Federal Standard Effective 1992
1st Federal Standard Adopted (Congress) 1987
NAECA Initial Federal Legislation Enacted 1987

Timeline reflects state standards from 2001 to present; federal standards from inception to present.