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Negative cooling load

asked 2025-10-17 17:45:32 -0600

nmoore
1 ●1

updated 2025-10-21 11:33:48 -0600

We're running lots of os-hpxml simulations and are finding some homes have negative annual cooling loads. We've narrowed that down to negative infiltration, shell conduction, and ventilation loads (natural and mechanical combined).

It's only a small subset of our modeled homes, but enough to make me say hmmm.

Weather file is USA Denver Lowry AFB. Sourced from: https://climate.onebuilding.org/WMO_R...

I have the hpxml model for a sample building. You can find it on google drive here: https://drive.google.com/file/d/108qI...

Is that expected behavior? If not, what would be causing this?

Thank you!

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You've tagged your question as pertaining to OpenStudio, i.e. EnergyPlus as simulation engine. Could you share an example OSM file (e.g. publicly-accessible Google Drive)?

Denis Bourgeois ( 2025-10-20 04:52:42 -0600 )edit

It would also be helpful to know what weather file you are using and an example HPXML file alongside the OSM file.

Craig Simmons ( 2025-10-21 07:39:47 -0600 )edit

I have the hpxml model for a sample building. You can find it on google drive here: https://drive.google.com/file/d/108qI...

Thank you for your assistance!

nmoore ( 2025-10-21 10:48:10 -0600 )edit

Are you sure you attached the right file? I ran it in OS-HPXML v1.8.1 and v1.9.1, both gave an annual cooling load of 7.9 MBtu.

shorowit ( 2025-10-23 13:40:07 -0600 )edit

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answered 2025-11-03 17:36:09 -0600

nmoore
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I have a suspicion the root cause is the handling of TMYx files, as described here: https://github.com/NREL/OpenStudio/is...

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That issue would not cause a negative cooling load, just a mis-sized cooling system. I also ran the file with your EPW and did not see a negative cooling load. Can you not post a screenshot or output file to show what you're seeing?

shorowit ( 2025-11-04 09:02:04 -0600 )edit

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