# IPLV and NPLV, Efficiency for the real world !!!

What is IPLV or NPLV ?

IPLV stands for integrated part load value and NPLV standfor non standard part load efficiency. IPLV or NPLV is used to evaluate efficiency of chiller at different loading condition. The calculation formulae of IPLV and NPLV is same. The only difference between IPLV and NPLV is that IPLV is calculated as per condition specified in AHRI_Standard_550-590(Table-1). While in NPLV is calculated as per site condition. Difference between IPLV and NPLV is indicated at (Table-3)

Why IPLV or NPLV is calculated?

COP and EER are calculated based on full load capacity but in the real world a chiller is hardly always running on full load capacity. So for evaluating  chiller efficiency at different part load condition IPLV or NPLV is calculated.  Performance of chiller is measured at different loading condition say 100%, 75%, 50% & 25% and IPLV or NPLV is calculated.

Calculation of IPLV and NPLV

For Water-chilling Packages covered by this standard, the IPLV or NPLV shall be calculated as follows:

1. Determine the Part-load energy efficiency at 100%, 75%, 50%, and 25% load points at the conditions Specified in Table-1&3
2. Use the following equation to calculate the IPLV or NPLV for units rated with COPR and EER.

IPLV or NPLV = 0.01·A + 0.42·B + 0.45·C + 0.12·D

For COPR and EER:

Where:

A = COPR or EER at 100% load

B = COPR or EER at 75% load

C = COPR or EER at 50% load

D = COPR or EER at 25% load

•  Use the following equation to calculate the IPLV.IP or NPLV.IP for units rated with kW/tonR:

IPLV or NPLV = 1/[(0.01/A)+(0.42/B)+(0.45/C)+(.12/D)]

Where:

A = Power Input per Capacity, kW/tonR at 100% load

B = Power Input per Capacity, kW/tonR at 75% load

C = Power Input per Capacity, kW/tonR at 50% load

D = Power Input per Capacity, kW/tonR at 25% load

Source: AHRI

Please refer AHRI document below for standard