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EnergyPlus Detailed hourly load distribtuion

asked 2016-04-26 10:05:30 -0600

kbk78 gravatar image

I am looking to get very detailed hourly load contribution for zone broken down by individual components. The “Sensibleheatgainsummary” report only provides an annual Sum. After going through the various outputs available I have shortlisted the following outputs that may provide what I am looking for.

  1. Lighting: “Zone Lights Convective Heating Rate”
  2. Equipment: “Zone Electric Equipment Convective Heating Rate”
  3. People: “Zone People Convective Heating Rate”
  4. Infiltration: “Zone Air Heat Balance Outdoor Air Transfer Rate”
  5. Diffuse solar: “Surface Window Transmitted Beam Solar Radiation Rate”
  6. Direct Solar: “Surface Window Transmitted Diffuse Solar Radiation Rate”
  7. Window conduction: “Surface Window Inside Face Glazing Zone Convection Heat Gain Rate”
  8. Wall Conduction: “Surface Average Face Conduction Heat Transfer Rate”

I would combine the Surface level outputs above from each zone.

Further intend to check if the zone is in heating or cooling mode, to obtain the load distribution separately during heating and cooling, from the output:

“Zone Air Heat Balance System Air Transfer Rate”

I am going in the right direction?

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This is tricky to do. Each time step, the simulation resolves the load balance and updates the zone air and surface temperatures. It doesn't "remember" whether the heat a surface gained came from lights or window solar radiation or plug loads. The convective rate variables you mention are instantaneous convective load for that timestep - not the sum of convective loads and past radiant loads that are now being realized as convective load.

See Jason's link on the Zone Component Load Summary. This is probably what you want, but it is only for sizing.

mdahlhausen gravatar image mdahlhausen  ( 2016-05-06 15:39:57 -0600 )edit

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answered 2016-05-04 12:52:36 -0600

You certainly will learn more about what is going on in your building model by looking at these variables. Unfortunately, the zone component loads are not an easy result to extract from EnergyPlus because of the the way that the heat balance approach lumps things together. For the peak loads in the year, you can take a look at the Zone Component Loads Summary table that can be produced when requested in the Output:Table:SummaryReports object by asking for the ZoneComponentLoadSummary report. This takes a little longer than a regular simulation since it simulates the sizing periods twice. You might want to read the section in the Engineering Reference to understand the way it is derived. It would be very difficult to follow the same approach for an entire year of a simulation.

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Feel free to remove this comment if it's not appropriate for the stackexchange-type site format, but I was going down this sort of rabbit hole today. I found this post and a few related on unmethours.com pop up first in my search, and the answers and resources have been a good reminder of the building physics involved. Thank you.

jfirrantello gravatar image jfirrantello  ( 2017-08-12 16:19:22 -0600 )edit

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Asked: 2016-04-26 10:05:30 -0600

Seen: 684 times

Last updated: May 04 '16