Hygric Parameters of Ecological Insulation Materials

[Simone]

Hi there,
I am trying to find hygric parameters for ecological insulation materials.
For one material it says in the data sheet that the the average value for maximum water absorption is 4,2 kg/m2 (Norm EN 1609).
Is this information of any help for me - can it be used for the Moisture Storage Function after converting it somehow?

Thanks

[Christian Bludau]

Hello Simone,

the moisture storage function can be approximated by using the reference water content (at 80% rh) and the free water saturation (at 100% rh). The maximum water content is close to the porosity of a material, as then all the pores are filled, which are not eg. closed.
So for approximating the moisture storage function you will need reference and free water content.
Please see also the programs online help for more information (search for approximate and see the glossary).

Christian

[Simone]

Hi Christian,
but I don´t have the water content (at 80% rh) and the free water saturation (at 100% rh). That´s why I am asking if the information given, which is the water absorption with 4,2 kg/m2 (Norm EN 1609) is of any help?
What parameters are really necessary for Ecological Insulation Materials (hemp, cork, sheepwool..) used as interior insulation?

Thanks
Simone

[Christian Bludau]

Hi Simone,
i did a mistake reading your post. EN1609 is the standard for water absorption of insulation. You can use that value as the free water saturation (but you have to transform that in kg/m³). But that is only one value, you still need the reference water content to approximate the moisture storage function.
Depending on the material for a realistic assessment also other values are needed. Here you can find a list with material parameters and test methods:
http://www.wufi-forum.com/viewtopic.php?t=301
The more information you have the better.
Christian

[Simone]

Hi Christian,
Water absorption (EN 1609) is tested for 24 hours with an immersion depth of 10mm. So you think I can convert this value and use it for free water saturation, right?
Might be a stupid question, but do you know how to convert kg/m2 into kg/m3?
In regard to further parameters needed, I read in the following post, that not all values are needed for "fibre materials"
http://www.wufi-forum.com/viewtopic.php ... ecological
Is this current knowledge?

Cheers
Simone

[Christian Bludau]

Dear Simone,
kg/m² / m (height of specimen) = kg/m³

Thats right, you can use that for the free saturation. Maybe try to find similar materials in the database and see what range the reference water content has. But in thsi case you should perform a sensitivity analysis of the assumed values.

As fiber insulations are normally hydrophobic, mainly the values for capillary water transport are not needed (or not possible to measure).
So for example an a-value or the transport coefficients are not needed. More interesting would be the moisture dependency on thermal conductivity.

Christian