Automatically Identifying the “True” Design Day Date to Match Known Peak Loads? [closed]

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Hi all,

I’m working on ASHRAE 140 Case 600 in EnergyPlus with a 15‑minute timestep. From a known reference I have both the peak cooling‑load value and its date (January 21), so I forced my IDF’s DesignDay to January 21 and immediately matched the expected peak results.

However, in a general project you won’t have that “standard” date in advance. I need a workflow that will:

Scan a full-year annual simulation and identify which calendar date produces the true peak load.

Automatically generate the appropriate DesignDay entry (date, temperature, solar conditions) so that sizing runs will reproduce that peak.

Although I’d prefer an EnergyPlus‑native approach (outputs, sizing objects, etc.), I’m open to post‑processing (ReadVarsESO, Python/Eppy, Excel) if that can reliably pinpoint the date.

My questions:

How can I programmatically extract the calendar date of the true annual peak cooling (or heating) load?

Once known, what’s the best way to convert that into a valid DesignDay definition (full weather profile) for subsequent sizing runs?

Are there any EnergyPlus features or scripts people use to “derive” a custom design day from an existing annual simulation?

Thanks in advance for any pointers or sample workflows!