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Best variables to use to capture hour-by-hour COP

asked 2019-11-03 21:08:09 -0600

y.tanaka gravatar image

updated 2019-11-11 08:39:35 -0600

I am trying to capture the instantaneous COP of various HVAC system upgrades on project_singlefamilydetached homes. Analysis is conducted using the timeseries.csv that's produced for each building after running simulations on Parametric Analysis Tool. My methodology is the following:

1.Add the values contained in:

`ZONE AIR SYSTEM SENSIBLE HEATING ENERGY (FINISHED BASEMENT ZONE) [J]`
`ZONE AIR SYSTEM SENSIBLE HEATING ENERGY (LIVING ZONE) [J]`
`ZONE AIR SYSTEM SENSIBLE HEATING ENERGY (UNFINISHED ATTIC ZONE) [J]`

The sum of those three values will serve as my "energy out"

2.Divide "energy out" by the Joule equivalent of electricity_heating_kwh (i.e. energy in) to get the COP at that timestep (energy out / energy in = COP)

However, doing the above produces somewhat odd results. For example, the following are graphs that display COP vs. Time for two upgrades: ASHP and GSHP.

ASHP image description

GSHP image description

The above two graphs describe the same building, using the same seed value in the Algorithm settings, with all other factors being the same except the HVAC System.

Why does the COP dramatically decrease and become extremely variable during the summer? Am I not capturing the entirety of "energy out" of the HVAC upgrade by summing up those three variables? Is electricity_heating_kwh not an accurate variable for representing the true energy usage of the HVAC system? Any help would be appreciated.

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answered 2019-11-04 11:56:08 -0600

From the Input/Output reference:

"Zone Air System Sensible Heating (and Cooling) Energy (and Rate) all report the heating or cooling delivered by the HVAC system to a zone. These values are calculated by multiplying the supply air mass flow rate by the difference between the supply air temperature and the zone air temperature. This does not always indicate the operation of heating or cooling coils. For example, cooling will be reported if the supply air is cooled due to the introduction of outside air, even if all coils are off."

To capture hourly COP, use output variables specific to the piece of equipment.

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Comments

Thank you! Yes, when I use the HEATING COIL HEATING ENERGY and HEATING COIL ELECTRIC ENERGY output, I receive more reasonable values.

y.tanaka gravatar imagey.tanaka ( 2019-11-09 16:25:55 -0600 )edit

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Asked: 2019-11-03 21:08:09 -0600

Seen: 84 times

Last updated: Nov 04