Examples of irregular, non-periodic changes in the total water content

[Alberto Morales]

Hi,

I have a historical wall made of:

outdoor (bottom of the image)
Granite stone
Unknown material
Brick
Air cavity
Timber
Indoor (top of the image)

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The unknown material has been modelled as 3 potential cases:
1- Solid calp limestone
2- Calp limestone/mortar/calp limestone (following Joseph Little's approach Stone/Mortar/Stone from Assessing risks in insulation retrofits using hygrothermal software tools)
3 - Brick

The only difference in the 3 models is just the unknown material, the rest is the same (orientation, initial condition, climates, etc)

The total water content I get is showed below:

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My concern is about the sharp increase of water content for the case where the unknown material has been modelled as a brick.

Following "Guideline for the Evaluation and Assessment of hygrothermal Calculation Results", it is mentioned that "Examples of irregular, non-periodic changes in the total water content Almost certainly impossible to evaluate meaningfully!" which would be my third case, however, I cannot find a way to improve it as the balances and convergence failures look good as you see below.

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The only conclusion I can make is that there is permanent moisture accumulation in the construction, however, dynamic equilibrium is reached.

Any thoughts or advice? What would you recommend I modify in my model, and are there any other aspects of the results that I should check?

Thanks in advance