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Calculate seasonal average COP for VRF system

asked 2020-01-16 08:00:40 -0600

dpud12 gravatar image

I have a model that I applied the "NZEHVAC" BCL measure to in order to add a VRF w/ DOAS system. I want to determine the seasonal average heating and cooling COPs of the system as a whole, as well as the VRF system only. What is the easiest way to do this in OpenStudio?

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answered 2020-01-16 09:58:39 -0600

For the VRF, add the output variables:

  • VRF Heat Pump Cooling COP
  • VRF Heat Pump Heating COP
  • VRF Heat Pump COP

To include the DOAS, add in:

  • Cooling Coil Total Cooling Energy
  • Cooling Coil Electric Energy
  • Heating Coil Heating Energy
  • Heating Coil Electric Energy

You can add these with the Add Output Variable measure or the Add Output Variables from csv measure. View them in Dview to get monthly and annual averages in the statistics page. You'll need to calculate the DOAS coil COP as Cooling or Heating energy / Electric Energy.

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@mdahlhausen Thanks for the quick response. Using those coil output variables is exactly what I usually do for other HVAC system types, however, when I use those with the VRF system I end up getting a heating COP below 1, which makes no sense for an electric heating system. There are only 400 unmet heating hours in my model, so it isn't that the system fails to meet the heating demand most of the time.

dpud12 gravatar imagedpud12 ( 2020-01-16 10:34:21 -0600 )edit

Seems like something is incorrect in the measure or the model. can you link to it?

mdahlhausen gravatar imagemdahlhausen ( 2020-01-16 12:38:28 -0600 )edit

Here is the model the only modification that I made after applying the NZEHVAC measure was to delete the ERV from the DOAS air loop

dpud12 gravatar imagedpud12 ( 2020-01-16 13:11:07 -0600 )edit

Please be aware of this issue on GitHub.

rraustad gravatar imagerraustad ( 2020-01-16 13:17:35 -0600 )edit

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Asked: 2020-01-16 08:00:40 -0600

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Last updated: Jan 16