IPLV/NPLV Calculator
Calculate part-load weighted efficiency for chillers per AHRI 550/590
Calculation Mode
Chiller Information
°C
IPLV Standard Conditions
Enter efficiency values at each AHRI standard load point
| Load % | Weight | CW/Ambient Temp | Efficiency | Power Input |
|---|---|---|---|---|
| 100% | 1% | 29.4°C (85°F) | 91 kW | |
| 75% | 42% | 23.9°C (75°F) | 58 kW | |
| 50% | 45% | 18.3°C (65°F) | 32 kW | |
| 25% | 12% | 18.3°C (65°F) | 15 kW |
IPLV Formula (AHRI 550/590):
IPLV = 0.01×A + 0.42×B + 0.45×C + 0.12×D
Where A=100%, B=75%, C=50%, D=25% load efficiency
IPLV = 0.01×A + 0.42×B + 0.45×C + 0.12×D
Where A=100%, B=75%, C=50%, D=25% load efficiency
Results
IPLV (COP)
6.82
EER: 23.3 | kW/RT: 0.52
Full Load Efficiency
5.50 COP
IPLV/Full Load Ratio
1.24
Avg Operating COP
7.23
Efficiency Tier
Premium Efficiency
Exceeds ASHRAE 90.1-2019 by >15%
Annual Energy Estimate
EFLH:
hrs
Annual Cooling:
1,000 MWh
Annual Power:
147 MWh
ASHRAE 90.1-2019 Minimum Efficiency
| Chiller Type | Min COP | Min IPLV |
|---|---|---|
| Water-Cooled Screw ≥150 RT | 5.33 | 6.28 |
| Water-Cooled Centrifugal ≥300 RT | 5.78 | 6.62 |
| Air-Cooled Screw ≥150 RT | 2.80 | 3.70 |
| Air-Cooled Scroll <150 RT | 2.96 | 3.90 |
Why IPLV Matters
- Chillers operate at part load 95%+ of the time
- Part-load efficiency often 20-40% better than full load
- IPLV better predicts actual annual energy use
- Lower CW temp at part load improves efficiency
Note:
Variable-speed chillers typically achieve 15-25% better IPLV than fixed-speed equivalents due to superior part-load performance.