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Why DB asks for the COP instead of EER for cooling systems?

asked 2021-10-29 02:26:50 -0600

updated 2021-10-29 07:29:21 -0600

I am a beginner in the DB modelling and I have a simple question: considering the efficiency of cooling systems is expressed in EER (Energy Efficiency Ratio), why DB asks for the COP (Coefficient of Performance) as if it were a heating system?

For example, if I have a multi split system with EER=3.32 (cooling) and COP=3.9 (heating), should I find out a way to convert the EER to COP or it's just a "name issue" and I can insert the EER value (3.32) where it asks for the COP of the cooling system in the DB?


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@brunaonety are you using the "Simple HVAC" model option (only defining efficiency inputs and not creating Detailed HVAC diagrams connecting components together)?

Aaron Boranian gravatar image Aaron Boranian  ( 2021-10-29 07:30:46 -0600 )edit

Hey @Aaron Boranian, yes, I am.. I am using the Ideal Loads option.. but I am a bit confused because it still asking for the efficiency of the systems.. Actually, what I need from the outputs of the simulation is the primary energy for the building, so I`m not sure if I should just ignore the equipment coefficients and calculate manually the primary energy using the sensible heating and cooling results or if these results already consider in any way these system efficiencies that DB asks as an input...

brunaonety gravatar image brunaonety  ( 2021-10-29 08:35:40 -0600 )edit

Does this post answer your question?

Aaron Boranian gravatar image Aaron Boranian  ( 2021-10-29 12:38:06 -0600 )edit

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answered 2021-10-31 05:00:12 -0600

I think the simple answer is that EnergyPlus (for which DB is an interface) uses COP for cooling coils. This is a long-standing situation! You need to convert EER to COP. For packaged systems, this requires adjusting EER to account for the fan power - not a simple numerical conversion. You can find conversion procedures (I think) by searching this forum or contacting me privately. I'd be happy to help. (jim at

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Asked: 2021-10-29 02:26:50 -0600

Seen: 69 times

Last updated: Oct 31 '21