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RE: [EnergyPlus_Support] effect of moisture on thermal insulation properties
I don't understand at all the distinction between "natural" and "artificial" for me mineral wool (glass and stone) are natural because they are made form natural raw materials like sand or basalt.
In my opinion mineral wool (glass and stone) don't absorb moisture from the ambient then no modification of thermal conductivity is possible (condensation it's only possible in bad constructions in some cases vapour barriers are needed)
I'm not sure (I'm not expert on this kind of products) If "natural" fibres can absorb moisture from the ambient but I think yes (cellulose, sheep wool,.. are currently hygroscopic products).then probably it's possible an increasing of thermal conductivity in "natural" fibers
Josep Sole
-----Mensaje original-----
De: Miguel Angel Pascual [mailto:mapascual@xxxxxxxxxxxx]
Enviado el: miércoles, 01 de octubre de 2003 9:04
Para: EnergyPlus_Support@xxxxxxxxxxxxxxx
Asunto: RE: [EnergyPlus_Support] effect of moisture on thermal insulation properties
Dear Christian,
I am sorry for this off-topic thread, but I am interested in this question.
Are you supposing a better thermal isolating behavior on the natural fibers
than in rockwool?
I think that if rockwool does not absorb any moisture and no condensation
happens within the wall, there won't be any modification in the thermal
isolating properties, so its performance will be better than materials that
absorb humidity.
Is it right?
Thanks in advance,
_____
De: Christian Struck [mailto:Christian.Struck@xxxxxxxxxxxxxxx]
Enviado el: lunes, 29 de septiembre de 2003 16:54
Para: EnergyPlus_Support@xxxxxxxxxxxxxxx
Asunto: [EnergyPlus_Support] effect of moisture on thermal insulation
properties
Dear E+ user,
I was asked to assess how the thermal properties of wet natural fibres
compare to wet artificial fibres(rockwool).
One claims natural fibres absorb the moisture, the thermal conductivity is
reduced not as bad as for artificial fibres, which do not have the
capability to absorb moisture at all.
I would have used the MTF algorithm in E+ to conduct the assessment. But...
since we have only one set of material properties available (vapour
diffusivity, prorosity, thermal gradient, isothermal moisture capacity) I
am not sure how to represent different degrees of stored moisture.
Another thought was to change the external humidity and recalculate the
u-value based on the resulting heat transfer through the wall of concern.
....still it would not take into account moisture stored within the fabric
since I assume the materials given represent the material dry.
I would seriously appreciate every single comment on my request! So please
do not hesitate to hit the keyboard!
Best Regards,
Christian
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