Unmet Hours

answered 2019-07-11 14:26:21 -0500

The purpose is to establish history in the thermal mass of the building surfaces. All simulation engines use some method to initialize this thermal history, but it's not as visible in some tools.

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Can you give me an intuition on this matter?

I have read this one and I can't seem to follow. I want to understand how to this works deeply or at least have a good intuition.

Sorry for the late reply. I really thought I have replied to this already.

Teepu ( 2019-08-10 06:14:06 -0500 )edit

From the Input Output Reference, Building object, Warmup Convergence: EnergyPlus“runs” the first day of the environment (starting with a set of hard-coded initial conditions: temperatures are initialized to 23C and zone humidity ratios are initialized to the outdoor humidity ratio) until the loads/temperature convergence tolerance values are satisfied (next two fields) or until it reaches “maximum number of warmup days”.

So, in a nutshell, everything starts at 23C, and the first simulation day is repeated until two successive days match within the criteria specified in the Building object.

MJWitte ( 2019-08-19 14:29:25 -0500 )edit

So for the "history in the thermal mass", the final conditions of the thermal mass in the warm up will be used for the actual simulation instead of arbitrarily declaring its initial temperature etc?

Teepu ( 2019-08-19 20:27:13 -0500 )edit

That is correct.

MJWitte ( 2019-08-28 16:57:58 -0500 )edit

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