WUFI

Hi Norbert,

The moisture content of a construction assembly will generally not remain at its initial value indefinitely. Instead, the materials gradually adjust towards a long-term equilibrium condition that is influenced by both the interior and exterior climate.

In your model, the concrete was ...

1- If I follow the guideline on “Assessing the Risk of Interstitial Condensation Runoff,” what minimum RC value should I consider? I ask because I do not have a water- and vapour-tight surface in my assembly, and I do not consider it would be appropriate to consider the concrete layer as one ...

The runoff guideline can be applied to condensation forming on the foil surface facing the cavity. However, it does not assess moisture accumulation inside the closed-cell PIR itself. For a smooth, water- and vapour-tight foil surface without adjacent fibrous insulation, the guideline starts with a ...

In WUFI, liquid water cannot accumulate directly between two adjacent material layers because the model does not represent an interface cavity. If you want to evaluate interstitial condensation and possible runoff at an interface, you would need to introduce an explicit air layer in the model ...

Hi Alberto,
regarding your questions:
1) yes, the condensation in air layers part
2) yes, the Rmet values - these should always be used if there is at least one metallic surface connected to the air gap
Christian

Hi Alberto,

Aluminum bright, dry vs. wet
The different long-wave emissivities are based on measurements from a research project and reflect the fact that bright aluminum behaves very differently when its surface is dry or covered by a thin water film. In practice, façade surfaces are often ...

Hi Alberto,

I would recommend leaving the aluminium panel itself out of the assembly and instead accounting for its vapour diffusion resistance through an additional diffusion resistance (sd-value) in the surface transfer conditions.

For the exterior surface properties, use the short-wave ...

Well done, thanks for sharing this pictures.
Have fun
Christian

Hi Alberto,

The guideline was primarily developed for standard ETICS systems with wood fibre insulation applied to typically mineral wall constructions.

As stated in the introduction:
This guideline provides support for the evaluation of wood fibre ETICS from manufacturers represented in the ...

Hi Alberto

Strong ventilation of the cavity can indeed increase the moisture risk for the sheathing board, especially in climates such as London.

While increased ventilation is often assumed to improve drying, it can also lead to lower temperatures within the ventilated cavity. A colder sheathing ...

I would be cautious about directly applying the "Guideline for the Calculation and Evaluation of an ETICS with Wood Fibre Insulation" to your assembly.

The guideline was developed specifically for ETICS systems with wood fibre insulation. Your wall build-up differs significantly, particularly ...

Yes, you can use the source there, if you want to test, what happens in the case of water can intrude there.

Hi Alberto,
it is a warning, not an error.
If you have a specific reason for setting these reduction factors, the warning can generally be ignored.
Only the center position is included in the surface calculation, which is why this warning is displayed. If you are using different positions, you can ...

The settings for PV-modules would be on page 21:

Hi,
the warning simply indicates that the settings do not follow the recommended configuration described in the guideline. If you have a specific reason for using different reduction factors, the warning can generally be ignored.

The recommended settings for the reduction factors are illustrated in ...