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Output average demand over a specific period with EnergyPlus?

asked 2019-01-30 18:26:52 -0600

pajordan's avatar

updated 2019-01-30 18:36:15 -0600

Is it possible to use tabular output to report average demand over a specific period with EnergyPlus?

I want to add a table to be included in the eplustbl.htm file that shows "peak demand" as defined by a particular utility or region (ex. California DEER peak demand savings are the average kW reduction over a 9-hour window - 2pm to 5pm over a three-day period).

I currently do this via post-processing of hourly output:variable output, but I was wondering if EnergyPlus can do the averaging for me somehow and report it in the .htm file.

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answered 2019-02-07 16:34:18 -0600

If you wanted the monthly and annual averages during certain time windows, then you could use Output:Table:Monthly with the following columns:

  1. "Schedule Value" for a schedule that is 1 from 2pm-5pm on applicable day types, type HoursPositive
  2. "Facility Total Electric Demand Power", type SumOrAverageDuringHoursShown - this will average during the hours counted in the previous column.

But if this is supposed to be the maximum 3-day moving average, you'll need to use an EMS (EnergyManagementSystem:*) program to do the calculations and generate a custom output variable. If you want the result for that to end up in the html output, you can use Output:Table:Monthly to report the monthly and annual maximum of the custom EMS output variable.

I also considered using UtilityCost:Ratchet but I don't see a way to set the demand window to 9 hours.

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This is so cool - thank you very much! I took the first approach of using Output:Table:Monthly and it seems to work great.

A couple notes: The Variable or Meter Name field can also just accept a schedule name (i.e., no need to use the Schedule Value variable). The variable as defined in the .rdd specifies whether or not it will be summed or averaged (ex. Output:Variable,*,Cooling Coil Electric Power,hourly; !- HVAC Average [W])

A follow-up question - what is the syntax in the Variable or Meter Name field for reporting out for just one key designator (such as a particular zone or system)?

pajordan's avatar pajordan  ( 2019-02-20 12:45:13 -0600 )edit

I am playing with reporting just HVAC system demand (heating coil, cooling coil, and fan) - using the above approach creates a separate monthly report for each system component (i.e., there will be a table for System1 heating coil, another table for System1 cooling table, etc.) - is there a way to have all of the output in one table?

pajordan's avatar pajordan  ( 2019-02-20 12:50:56 -0600 )edit

To answer both questions, each table expects all of the columns to share a common key name, so there is no syntax for specifying a single instance, and components that share different key names will be in separate tables. Sometimes one can find equivalent variables that are all under the same key, such as air loop name. Or, you could create custom meters that grab the desired values and then use the meter names in the monthly report (meters only have one instance).

MJWitte's avatar MJWitte  ( 2019-03-05 15:58:15 -0600 )edit

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Asked: 2019-01-30 18:26:52 -0600

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Last updated: Feb 07 '19