Equipment Performance Data
AHRI equipment ratings, SEER2/EER2/HSPF2 efficiency metrics, expanded performance tables, capacity correction factors, and how to read manufacturer data for Manual S equipment selection.
- Interpret AHRI rated performance data for residential HVAC equipment
- Explain SEER2, EER2, and HSPF2 efficiency metrics and their testing conditions
- Use expanded performance data to determine capacity at actual design conditions
- Apply capacity correction factors for altitude, airflow, and entering air conditions
Lesson 1
AHRI Ratings & Efficiency Metrics
What AHRI Ratings Tell You
The Air-Conditioning, Heating, and Refrigeration Institute (AHRI) certifies the performance of HVAC equipment through standardized testing. AHRI ratings allow apples-to-apples comparison of equipment from different manufacturers because all units are tested under the same conditions. However, AHRI ratings represent performance at specific standard conditions that rarely match the actual design conditions of a specific project.
AHRI standard rating conditions for cooling:
- Outdoor temperature: 95 F dry-bulb
- Indoor return air: 80 F dry-bulb / 67 F wet-bulb
- Airflow: Manufacturer's rated CFM (typically 400 CFM/ton)
These conditions represent a typical hot summer day in a moderate climate. But if you are designing for Phoenix at 108 F outdoor, or for a humid climate where the return air wet-bulb is 72 F, the actual equipment performance will differ significantly from the AHRI rating.
SEER2 - Seasonal Energy Efficiency Ratio
SEER2 (Seasonal Energy Efficiency Ratio, version 2) is the primary cooling efficiency metric for residential equipment. It represents the total cooling output (in BTU) divided by the total electrical energy input (in watt-hours) over an entire cooling season, tested under the M1 test procedure with a more realistic external static pressure of 0.50 IWC.
SEER2 = Seasonal Cooling Output (BTU) / Seasonal Energy Input (Wh)
SEER2 accounts for part-load performance across a range of outdoor temperatures, not just peak conditions. A higher SEER2 means less electricity consumed per unit of cooling over the season.
Current federal minimum SEER2 requirements (effective January 2023):
| Region | Split System Minimum | Package System Minimum |
|---|---|---|
| Northern states | 13.4 SEER2 | 13.4 SEER2 |
| Southern states (SE/SW) | 14.3 SEER2 | 13.4 SEER2 |
| ENERGY STAR (national) | 15.2 SEER2 | 14.3 SEER2 |
EER2 - Energy Efficiency Ratio
EER2 measures cooling efficiency at a single steady-state condition (95 F outdoor, rated airflow). Unlike SEER2 which is a seasonal average, EER2 represents peak-load efficiency:
EER2 = Cooling Capacity (BTU/h) / Power Input (W) at rated conditions
EER2 is important for hot climates where the system runs near full capacity for extended periods. A system with high SEER2 but low EER2 may perform well at part-load but struggle during peak conditions.
HSPF2 - Heating Seasonal Performance Factor
HSPF2 measures the seasonal heating efficiency of heat pumps:
HSPF2 = Seasonal Heating Output (BTU) / Seasonal Energy Input (Wh)
HSPF2 accounts for the heat pump's decreasing capacity and efficiency as outdoor temperature drops, including supplemental electric resistance heat usage. The federal minimum for heat pumps is 7.5 HSPF2.
SEER2 (Seasonal Cooling)
Measures: Cooling efficiency over full season
Includes: Part-load and full-load performance
Best for: Comparing annual cooling energy costs
Minimum: 13.4 - 14.3 (region-dependent)
EER2 (Peak Cooling)
Measures: Cooling efficiency at 95 F outdoor
Includes: Full-load only, single condition
Best for: Hot climates with sustained peak loads
Typical: 10.0 - 13.0 for residential units
HSPF2 (Seasonal Heating)
Measures: Heat pump heating over full season
Includes: Defrost cycles and auxiliary heat
Best for: Comparing heat pump annual heating costs
Minimum: 7.5 for heat pumps
AHRI ratings provide standardized performance data at specific test conditions (95 F outdoor, 80/67 F return air). SEER2 measures seasonal cooling efficiency, EER2 measures peak cooling efficiency, and HSPF2 measures seasonal heat pump heating efficiency. These ratings allow fair comparison between equipment, but actual performance at design conditions requires expanded data tables.