Peak load results difference between "HB Peak Loads" and Openstudio

Dear community!

I am trying to get the peak cooling and heating load of building, but not sure how to calculate it since there is a huge difference in the result from “HB Peak Loads” component and Openstudio.

  1. As below capture shows, total peak cooling from “Peak loads” is much higher than the one from openstudio zsz. I’ve checked the results, and peak load of each room also has huge difference.

  2. The peak of sum from “cool_bal” also not same with peak cooling results.

  3. For heating, the result from “Peak Loads” and openstudio is similar, but the peak heating results is different with the sum of “heat_bal” data.

Attached the grasshopper script I’ve tested.
It would be very helpful if you can provide some comment on it.
Thanks!

testmodel.gh (121.1 KB)

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seems there is no solar gain results for sizing calculation.
May I know why it doesn’t count solar load?

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Seems the peak load difference between “HB Peak Loads” and Openstudio is because of solar gain load.
As below graph shows, it is unable to get the solar load for sizing day, but the annual energy balance has solar gain.
And the peak loads from openstudio is very similar with the one from “HB Peak Loads” without solar gain load

May I know if it is some bug with openstudio? or I didn’t setup the HB script properly?

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I think I found the issue with “HB Model to OSM” component. Sky properties input from ddy file will be missed when this component write the idf file.

If I change the idf file same with “HB Peak Loads” and run again, it will get the solar gain results for summer sizing day.

So, the question is, how I can keep these two input from ddy for openstudio sizing?
@chris May I know if you any idea on this issue? many thanks!

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I had the exact same problem.

I saw a post by chris and got work reconstructing my DDY file with the ASHRAE clearsky model which is sufficient for my needs. I also realized that using the LB EPW to DDY the results are just 2 design days (winter and summer, the DDY had multiple months of design days) and also with clearsky. With this, the results are very similar between the HB to OSM and Peak Loads!

Maybe try to unify the sky model using chris’s post that I mentioned along my screenshot.

Hi, @adrisonet
Many thanks for your reply and suggestion.
I’ve tried your recommendation to re-create the ddy file, but the problem I had is the openstudio module delete the sky properties data when running the design day sizing (Peak load component doesn’t have this issue, it works well).
Therefore, even I reconstructed the ddy file as your way, the sky properties will be ignored by openstudio component.