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What's the COP/EER of Ideal Loads Air System

asked 2022-10-12 06:39:37 -0600

Liza Lee's avatar

updated 2022-10-12 09:19:26 -0600

Hi, So I used "ZoneHVAC:IdealLoadsAirSystem" in one simulation case. I have the cooling and heating energy consumption. Just wondering, what's the COP/EER of this ideal air conditioning system? Thank you very much!

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Same question as this.

shorowit's avatar shorowit  ( 2022-10-12 12:10:43 -0600 )edit

Thank you. But... " This component can be thought of as an ideal unit that mixes air at the zone exhaust condition (or plenum outlet condition when a plenum is attached) with the specified amount of outdoor air and then adds or removes heat and moisture at 100% efficiency in order to produce a supply air stream at the specified conditions." This sentence is not saying that COP is 1. It's talking about the efficiency caused by specific components, the ideal system doesn't have specific parts, so efficiency is 100%

Liza Lee's avatar Liza Lee  ( 2022-10-13 00:36:41 -0600 )edit

If COP of the ideal loads air system is really 1, it's unreasonable. In fact, air conditioning system's COP/EER is always bigger than 1. In reality, air conditioning system's COP/EER is among 3 to 6.

Liza Lee's avatar Liza Lee  ( 2022-10-13 00:40:15 -0600 )edit

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answered 2022-10-13 10:23:51 -0600

updated 2022-10-13 10:25:10 -0600

An ideal air system is not mean to be a realistic piece of equipment. It's often used to calculate the building's heating and cooling loads or is used when the HVAC equipment is not known. It has a constant year-round COP of 1, though I believe you can specify a heating or cooling efficiency for it using the EnvironmentalImpactFactors object -- see the District Heating Efficiency and District Cooling COP fields.

If you want to model an air conditioning system, you can add a DX coil object to your model. Unlike an ideal air system, air conditioners and heat pumps will have COPs that vary throughout the year based on (primarily) outdoor temperature.

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Thank you very much. This is really, wow, an air conditioning system with COP of 1, in my opinion, i will consider the energy consumption of this simulation as wrong. It's too far away from reality. Thank you for your suggestions, i will try to make a new air conditioning system.

Liza Lee's avatar Liza Lee  ( 2022-10-13 10:40:01 -0600 )edit
1

Here's a relevant feature request to add efficiency fields to the District* objects. https://github.com/NREL/EnergyPlus/is...

MatthewSteen's avatar MatthewSteen  ( 2022-10-14 11:34:15 -0600 )edit

Hi Liza, it is unrealistic, yes, but keep in mind, that a use case of using COP=1 is to easily postprocess your simulation result in e.g. Excel at early stages of the design.

furtonb's avatar furtonb  ( 2022-10-14 13:23:48 -0600 )edit

Sure, Thanks. I think it would be better if it's clearly explained in the documents.

Liza Lee's avatar Liza Lee  ( 2022-10-14 13:33:21 -0600 )edit
1

@Liza Lee it's mentioned here. https://bigladdersoftware.com/epx/doc...

This component can be thought of as an ideal unit that mixes air at the zone exhaust condition (or plenum outlet condition when a plenum is attached) with the specified amount of outdoor air and then adds or removes heat and moisture at 100% efficiency in order to produce a supply air stream at the specified conditions.

MatthewSteen's avatar MatthewSteen  ( 2022-10-14 13:41:11 -0600 )edit

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Asked: 2022-10-12 06:39:37 -0600

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Last updated: Oct 14