When it comes to home cooling, understanding air conditioner efficiency is crucial for managing energy costs and making informed purchasing decisions. Comparing the efficiency of different air conditioners often involves navigating terms like SEER and SEER2. Our comprehensive guide breaks down these ratings and other key factors to help you effectively Compare Air Conditioner Efficiency and choose the best system for your needs. Using tools like a SEER calculator can further assist in estimating potential savings and comparing cooling costs between different models, ensuring you make an energy-smart choice for your home.
Understanding SEER and SEER2 Ratings
SEER, which stands for Seasonal Energy Efficiency Ratio, is a fundamental metric for evaluating the energy efficiency of air conditioners and heat pumps. It represents how efficiently a unit cools your home over an entire cooling season. A higher SEER rating indicates greater energy efficiency, meaning the air conditioner consumes less electricity to provide the same amount of cooling.
SEER2 is the updated efficiency rating system that became the new standard on January 1, 2023. From this date forward, all newly manufactured air conditioners are required to have a SEER2 rating. This update was implemented to provide a more accurate reflection of real-world energy consumption by air conditioners and heat pumps.
Decoding SEER and SEER2 Calculation Methods
Both SEER and SEER2 use the same fundamental calculation to determine efficiency:
SEER/SEER2 = Total heat removed from a home during a cooling season (BTU) / Total electrical energy used (Wh)
The key distinction between SEER and SEER2 lies in the testing procedures. To ensure accurate efficiency ratings, air conditioners undergo standardized testing. The shift to SEER2 involved updated testing requirements designed to better simulate actual operating conditions. One significant change is the requirement for manufacturers to test units under higher external static pressure.
This adjustment in testing methodology results in SEER2 ratings that are generally about 4.5% lower than SEER ratings for the same unit. While seemingly similar, comparing SEER and SEER2 ratings directly is not an apples-to-apples comparison. A system with a SEER2 rating is effectively more efficient than a SEER-rated system with the same numerical value. Specifically, a SEER2-rated system is approximately 4.71% more efficient than a SEER system with an identical rating number. To visualize this, using an air conditioner energy calculator and setting both SEER and SEER2 sliders to the same value will demonstrate the slight difference in estimated energy cost savings.
For a detailed understanding of SEER2 calculations and the updated testing protocols, refer to the AHRI Standard 210/240 (210/240-2023).
Other Efficiency Metrics: HSPF and EER
Beyond SEER and SEER2, two other acronyms are relevant when comparing air conditioner efficiency: HSPF and EER.
HSPF and HSPF2 for Heat Pumps
HSPF, or Heating Seasonal Performance Factor, measures the heating efficiency of heat pumps. Heat pumps are unique in that they provide both heating and cooling capabilities. While SEER (or SEER2) rates cooling efficiency, HSPF (or HSPF2) assesses heating efficiency. Like SEER, HSPF is calculated by dividing the total heat output in BTU during a typical heating season by the total electrical energy consumed in watt-hours.
Similar to the SEER to SEER2 update, HSPF also transitioned to HSPF2 in 2023 with revised testing procedures. All heat pumps manufactured from 2023 onwards now feature HSPF2 ratings. For detailed insights into heat pump heating efficiency, resources like an AFUE Savings Calculator can be valuable.
EER and EER2: Instantaneous Efficiency
EER, or Energy Efficiency Ratio, is another measure of air conditioner and heat pump efficiency. EER2 is the updated version, effective from January 1, 2023. EER2 calculation mirrors SEER2 (BTU/Wh), but the key difference lies in how outdoor temperature is considered. EER2 is based on a fixed outdoor temperature of 95°F, while SEER2 calculations account for a range of outdoor temperatures from 65°F to 104°F, reflecting seasonal temperature variations.
SEER2 is generally considered the more comprehensive efficiency metric due to its consideration of seasonal performance. EER2, with its single-temperature benchmark, provides a snapshot of efficiency under specific, high-temperature conditions, which may be less representative of overall, real-world performance.
Current Air Conditioner Efficiency Standards
Minimum energy efficiency standards are mandated nationwide for all air conditioners and heat pumps. The most recent update to these standards took effect on January 1, 2023, coinciding with the SEER2 rating system rollout. These new standards necessitate higher minimum efficiency ratings compared to previous regulations.
The map and chart below illustrate the current minimum energy efficiency requirements across different regions of the United States, incorporating both SEER and SEER2 ratings for easier comparison.
| North | Southeast* | Southwest** | |
|---|---|---|---|
| SEER / SEER2 | HSPF / HSPF2 | SEER / SEER2 | |
| Split System AC <45K BTU/h | 14 / 13.4 | – | 15 / 14.3 |
| Split System AC >45K BTU/h | 14.4 / 13.4 | – | 14.5 / 13.8 |
| Split System Heat Pump | 15 / 14.3 | 8.8 / 7.5 | – |
| Single Packaged AC† | 14 / 13.4 | – | – |
| Single Packaged Heat Pump | 14 / 13.4 | 8.0 / 6.7 | – |
| Space-Constrained AC† | 12 / 11.7 | – | – |
| Space-Constrained Heat Pump† | 12 / 11.9 | 7.4 / 6.3 | – |
| Small-Duct High-Velocity System† | 12 | 7.2 / 6.1 | – |
*Southeast includes: Alabama, Arkansas, Delaware, Florida, Georgia, Hawaii, Kentucky, Louisiana, Maryland, Mississippi, North Carolina, Oklahoma, Puerto Rico, South Carolina, Tennessee, Texas, Virginia, the District of Columbia, and U.S. territories. **Southwest includes: Arizona, California, Nevada, and New Mexico. ***The 10.2 EER (9.8 EER2) amended energy conservation standard applies to split-system air conditioners with a SEER rating greater than or equal to 16. †Energy conservation standards for single-package, small-duct high-velocity and space-constrained product classes remain unchanged.
Even if your existing air conditioner doesn’t meet these current minimum standards, it doesn’t necessitate immediate replacement as long as it’s functioning. However, HVAC contractors are restricted from installing new systems that fail to meet these standards, with limited exceptions. It’s advisable to compare your current system’s efficiency with higher-rated models using a calculator to understand potential energy savings from an upgrade.
Locating Your Air Conditioner’s SEER or SEER2 Rating
To compare air conditioner efficiency effectively, you’ll need to know the SEER or SEER2 rating of your current unit. Here are several ways to find this information:
- Energy Guide Label: Check the outdoor condenser unit for a yellow Energy Guide label. Newer units often have this label prominently displayed, indicating the SEER rating and other specifications.
- Air Handler Sticker: If no label is visible on the condenser, inspect the air handler, typically located indoors (attic, garage, etc.). It may have a sticker with unit information, including the SEER rating.
- Manufacturer Information: Locate the manufacturer, model number, and serial number on the condenser or air handler. You can then visit the manufacturer’s website and search for your unit’s specifications using these details. Customer service hotlines are also available for assistance.
The Importance of Matched Systems
For optimal efficiency, the condenser and air handler of your air conditioner must be a matched system. Manufacturers design air handlers to be compatible with specific condensers to ensure peak performance. While HVAC professionals are generally expected to install matched sets, mismatches can occur. A mismatched system is unlikely to achieve the advertised SEER or SEER2 efficiency.
Understanding AC Tonnage: Cooling Capacity
AC tonnage is a term used to describe an air conditioner’s cooling capacity, not its physical weight. Tonnage indicates the amount of heat an air conditioner can remove from a room per hour. One ton of air conditioning equals 12,000 BTUs of heat removed per hour. A two-ton unit removes 24,000 BTUs per hour, and so on.
The appropriate AC tonnage for your home depends on factors like square footage, number of occupants, and window quantity. The table below provides a general guideline for typical AC sizes based on square footage. Larger homes may require multiple units. Residential air conditioners typically range up to 5 tons; larger capacities are considered commercial.
Typical Tonnage by Square Footage
| SQFT | Size (in Tons) |
|---|---|
| 750 to 1,000 | 1.5 – 2 |
| 1,050 to 1,400 | 2.5 |
| 1,450 to 1,700 | 3 |
| 1,750 to 1,900 | 3.5 |
| 1,950 to 2,200 | 4 |
| 2,250+ | 5 |
By understanding SEER, SEER2, and other efficiency metrics, alongside AC tonnage, you can effectively compare air conditioner efficiency and make informed decisions for a comfortable and energy-efficient home.
