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How do I calculate COP and IPLV from EER?
How do I calculate COP and IPLV from EER?

Differences between EER, SEER, COP, IPLV, and NPLV.

Akshay Padwal avatar
Written by Akshay Padwal
Updated over a week ago

The Energy Efficiency Ratio (EER) of a particular air conditioner is calculated by dividing the input electrical power (measured in watts) by the amount of cooling created (measured in British Thermal Units or BTU) under a single set of conditions.
The standard condition for calculating EER is an outdoor temperature of 95°F and inside temperature of 80°F with 50% humidity. Higher EER equipment uses less energy and helps reduce carbon emissions.

The platform uses COP value for the energy usage calculations. To convert EER to COP, please use the following formula:

COP = (EER)/(3.41214)

The Seasonal Energy Efficiency Ratio (SEER) measures the cooling efficiency of an air-conditioning or heat pump system, similar to EER, but is instead related to a typical (hypothetical) season rather than for a single rated condition. The SEER is a weighted average of EERs over a range of rated outside air conditions following a specific standard test method.

COP = (SEER*1055) / 3600

Similar to how SEER is a rating of real-world seasonal or average performance of standard air conditioning systems, Integrated Part Load Value (IPLV) and Non-Standard Part Load Value (NPLV) are ASHRAE/AHRI's official efficiency rating of hydronic air-to-water and water-to-water (geothermal) chillers and heat pumps and are useful metrics for conducting a direct comparison of real world operating efficiency between various brands and models. The difference between these two ratings is that IPLV is based on a chiller loop temperature of 44°F, while NPLV uses a non-standard loop temperature of 55°F; by utilizing non-standard loop temperatures, it's possible to achieve higher system efficiencies, given that the equipment's coils are appropriately enlarged to achieve the same BTU and thermostat satisfaction requirements as a 44°F loop.

To calculate IPLV, please use the following formula:

IPLV = 0.01A+0.42B+0.45C+0.12D

(NPLV uses the same formula)

Where the variables A, B, C, D are either the COP or EER at a given part load. When calculating the IPLV the COP or EER must be used consistently:

  • A = EER/COP @ 100% Load

    • (Means that 1% of the time the unit needs to run at around 100% capacity)

  • B = EER/COP @ 75% Load

    • (Means that 42% of the time the unit needs to run at around 75% capacity)

  • C = EER/COP @ 50% Load

    • (Means that 45% of the time the unit needs to run at around 50% capacity)

  • D = EER/COP @ 25% Load

    • (Means that 12% of the time the unit needs to run at around 25% capacity)

For additional common conversions see this guide.

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