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Add design day calc to beopt idf's

asked 2023-07-20 14:54:19 -0500

cmui's avatar

I'd like to compare the HVAC sizing determined by beopt (close to Man-J) vs a energy plus design day (99% and 1% conditions from a location's ddy file). What modifications are needed to the idf produced by beopt to see system sizing in the energyplus output table? I've already added the SizingPeriod:DesignDay information via the eplus idf editor.

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answered 2023-07-20 15:43:59 -0500

Many years ago, we scoped out what it would take to do this. Here was the list of items we produced at the time; I can't say whether it covers everything, but it ought to be a good start.

  • Update winter/summer design days for all internal schedules based on Manual J approach (Internal gains should be 0 for winter design load calculation)
  • Include winter/summer thermostat schedules based on setpoints used by Manual J approach (75°F for cooling, 68°F for heating)
  • Update Sizing:Zone and Sizing:System 'Central Cooling Design Supply Air Temperature'
  • Update Sizing:Zone and Sizing:System 'Central Heating Design Supply Air Temperature'
  • Update Sizing:System 'Design Outdoor Air Flow Rate' to 0 m3/s
  • Update Sizing:System '100% Outdoor Air in Cooling (and Heating)' to 'No'
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Ok, looks like I have something working. Most beopt models will default to 20% duct leakage, and some R value for duct insulation. Is the 'Calculated Design Load' the value of heating delivered to the space, or produced by the heating source (furnace or otherwise).

cmui's avatar cmui  ( 2023-07-20 18:03:41 -0500 )edit

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Asked: 2023-07-20 14:54:19 -0500

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Last updated: Jul 20 '23