# What is COP, IPLV, NPLV & SPLV in Air Conditioner System

COP or Coefficient of performance is the key performance evaluation parameter of any air conditioning system. It is the ratio of cooling energy output for the amount of work done. The Higher the value of COP higher is the performance and the lower the power consumption. COP value can define the performance of the AC system at full load conditions and this value cannot be used to assess the exact performance of the system at the actual operating conditions that too project-specific. Hence to assess the performance at part load conditions different terms like IPLV, NPLV & SPLV are used:

Integrated Part Load Value (IPLV) :

Generally, the performance value, COP of an air conditioning machine is derived considering 100% loading. But most of the air conditioners run at design load only at 1% of their lifetime. Hence to calculate the exact performance value considering different loading conditions, IPLV is used.

IPLV is derived considering a weighted average of 4 loading points (25%,50%,75%&100%) – the most appropriate reference

IPLV Formula = 0.01A+0.42B+0.45C+0.12D; where A,B,C&D are the COP values at 4 loading points respectively.

IPLV Calculation:

Instantaneous values of COP for 4 specific load points at standard AHRI conditions will be generally tested and then those values will be inserted in the above formula to obtain the IPLV for a system. Most of the times the conditions specified under AHRI won't be possible on the ground due to many constraints like variations in distribution system design, climatic conditions and many more. That's the reason NPLV and SPLV come into the picture.

Net part-load value (NPLV):

Net Part load value is also used to assess the performance of the air conditioning system at part load conditions. The formula for calculating the IPLV and NPLV is same as above. The difference between IPLV and NPLV is that the values A.B, C.D are calculated based on standard values specified by AHRI for IPLV and are calculated based on desired values for NPLV. Please refer to the below table on  IPLV vs NPLV.

Specific or System Part Load Value (SPLV):

SPLV is a project-specific, single number, part-load efficiency indicator introduced by Carrier that is calculated using the equation form defined in ARI 550/590- 1998. Unlike IPLV or NPLV, the factors used to calculate SPLV are project-specific and consider multiple chiller applications, actual operating hours, and project-specific operating conditions.

kW/TR :

kW/TR is nothing but the performance value for an air conditioning system where the numerator is represented in electrical form and the denominator is represented in thermal form. Where in COP, both numerator and denominator are represented in thermal terms.

Conversion from COP to kW/TR:
• COP = 12/ ( kW/TR ) / 3.412