Sizing Day Error

My simulation runs, but for some reason the system is sizing using January 1st for both heating AND cooling (unsurprisingly, this is resulting in a lot of unmet cooling hours).

The DDY file is adjacent to the EPW file. When I try to specify the path to the DDY file, the simulation fails and I get this error telling me I have not specified any design environments for system sizing:

I am running HB version 0.0/65

Some additional information:

  • I am using the following EPW/DDY file: USA_VA_Sterling-Washington.Dulles.Intl.AP.724030_TMY3.ddy (17.2 KB)

  • Inside the DDY file are the correct sizing days, but when I open up the IDF file, every date is 1/11.

  • Other climate files seem to translate their sizing days to the IDF correctly, but all of them have the same simulation error when I try to specify the path to the DDY

Hi @Elliot_Glassman

I do not have a direct answer for your problem, I only know by default the following settings are used for the energy Simulation Parameters:
1 - 6 timeSteps per hour
2 - A shadow calculation that averages over multiple days (as opposed to running it for each timeStep)
3 - A shadow calculation frequency of 30 (meaning that the shadow calulation is averaged over every 30 days)
4 - A maximum of 3000 points used in the shadow calculation. (This may need to be higher if you have a lot of detailed context geometry)
5 - A solar energy calculation that includes both interior and exterior light reflections.
6 - A simulation including a zone sizing calculation, a system sizing calculation, a plat sizing calculation, and a full run of the energy use ofver the analysis period. The simulation is not run for the sizing period by default.
7 - A system sizing period that runs from the extreme periods of the weather file and not a ddy file.
8 - City terrian.

I found this out by looking into the inSsz.csv file:

Why they chose for this approach I don’t know. Perhaps @chris knows the reason behind this.
I also noticed that the system size values from the EIO file where much lower then the maximum values which where stored in the inSsz.csv file.

The results of the zone sizing reported in the EIO file where easy to detect in the inZsz.csv file, but for the system sizing I could not find any relationship.

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Hi @Elliot_Glassman,

I retried running the simulation with an .ddy file attached, and I get the same error as you:

  1. The simulation has not run correctly because of this severe error:
    ** Severe ** CheckEnvironmentSpecifications: Sizing for Systems has been requested but there are no design environments specified.

The discription for the input runSimForSizingPeriods:

Set to “True” to have EnergyPlus run a simulation for the Sizing periods specified in the IDF. The default is set to “False.” By default, the sizing periods are set to the extreme hot and extreme cold weeks of the weather file but a custom ddy file can also be specified with the “Honeybee_Energy Simulation Par” component.

According to this discription, setting this to false should allow adding a .ddy file for the simulation. It is a pitty it does not work.