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Initial temperature unmatching

asked 2024-09-19 22:32:51 -0500

Selma Inger's avatar

updated 2025-05-06 17:34:41 -0500

Dear UnmetHours members,

Hello, I am developing fan-assisted mixed-mode ventilation algorithm in EnergyPlus 9.4.

I found unmatching between baseline(Window on/off control) and developing model (window on/off + Fan-assisted ventilation). (but not alarmed)

Although they have same inputs, same internal heat gain, same geometry and same EPW, their initial temperature differs at a start day of simulation (January, 1st).

The first figure shows baseline and the second figure shows developing model.

They are using ZoneIdealLoad (no limit). Only different inputs are EMS code and ceiling fan object. But I deactivate zone sizing option and turn off ceiling fan Fan-assisted ventilation model during unoccupied period (including simulation start point)

If you have experience in solving this kind of problem, please help me to solve.

Thanks.

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answered 2024-09-19 22:33:19 -0500

Selma Inger's avatar

updated 2024-09-19 22:34:09 -0500

Here is figures

image description image description

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@Selma Inger since this isn't an answer to your initial question, please instead edit your original post to add these images. Once you're finished, delete this answer post.

Aaron Boranian's avatar Aaron Boranian  ( 2025-05-06 17:35:32 -0500 )edit
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answered 2025-05-06 17:38:19 -0500

You're seeing the difference in results from the warmup process that EnergyPlus performs. The difference in your window opening strategies are used over this warmup process, which is why the run period results that you're plotting have different initial conditions for zone air temperature.

If you search Unmet Hours for "energyplus warmup", you'll find many posts on the topic.

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Asked: 2024-09-19 22:32:51 -0500

Seen: 144 times

Last updated: May 06