I have WUFI Pro 5.1 and have used the newest version of WUFI BIO 3.0 to look at the mold potential of a construction in areas within the construction (as is now possible). The help guide still says that only the mold potential on an interior surface should be considered as reliable, but with being able to look at a position within the construction, has the program been improved so that I can rely on the WUFI BIO results for areas NOT on the interior surface?
Additionally, how much faith should I put in results that show a mold potential for areas that are protected by a rain screen or vented over roof?
Thank-you,
Linda
Monitor locations in WUFI BIO
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LindaWhaley
- WUFI ORNL Instructors
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Christian Bludau
- WUFI SupportTeam IBP
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Hello Linda,
the LIM-curves as well as the model was developed for the use at the interior surface. If you use it for the areas below the interior surface, there is no guarantee, that the values are right. In building materials you can for example have biocides for avoiding mould and such things. Usually if there is no air there will be no mould as well. But if you check for example the surface of an interior vapor barrier with WUFI Bio and no mould is shown, you can be quite sure that there are no mould conditions at all.
Concerning your additional question: We do not use the model for the outer surface. There are more mould species as well as algae, which are not included in the model. The model is inapplicable for the outer surface or the "cold side" of a construction.
Christian
the LIM-curves as well as the model was developed for the use at the interior surface. If you use it for the areas below the interior surface, there is no guarantee, that the values are right. In building materials you can for example have biocides for avoiding mould and such things. Usually if there is no air there will be no mould as well. But if you check for example the surface of an interior vapor barrier with WUFI Bio and no mould is shown, you can be quite sure that there are no mould conditions at all.
Concerning your additional question: We do not use the model for the outer surface. There are more mould species as well as algae, which are not included in the model. The model is inapplicable for the outer surface or the "cold side" of a construction.
Christian
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LindaWhaley
- WUFI ORNL Instructors
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- Joined: Fri May 13, 2011 11:59 am -1100
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Thank-you Christian. Are there plans to allow WUFI Bio to check for Mold growth within a construction in the future or is this feature more for curiosity sake? Using your advice of "But if you check for example the surface of an interior vapor barrier with WUFI Bio and no mould is shown, you can be quite sure that there are no mould conditions at all. " my colleague Graham and I did some calculations with the idea that a green light result of the WUFI Bio even within a construction was a good indication of no mold (though not a total guarantee because as you say WUFI Bio was designed for the interior surface results).
While watching the calculation results post one day for the surface of OSB in the center of a construction I noticed that the first year was a yellow light and the remaining years of the 5 year run were green lights. The final result was a green light. Does one interpret this as one year may be a problem and remaining years would be good? I would imagine the same variation in results can also show on the interior surface, so this is more a question of how your stoplight system is designed to operate. I am the education chair at Passive House NorthWest and Graham is a technical committee member with Passive House Institute US. We want to make sure we understand the system in order to share the proper knowledge within the Passive House community.
Thank-you!
Linda
While watching the calculation results post one day for the surface of OSB in the center of a construction I noticed that the first year was a yellow light and the remaining years of the 5 year run were green lights. The final result was a green light. Does one interpret this as one year may be a problem and remaining years would be good? I would imagine the same variation in results can also show on the interior surface, so this is more a question of how your stoplight system is designed to operate. I am the education chair at Passive House NorthWest and Graham is a technical committee member with Passive House Institute US. We want to make sure we understand the system in order to share the proper knowledge within the Passive House community.
Thank-you!
Linda
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Christian Bludau
- WUFI SupportTeam IBP
- Posts: 1140
- Joined: Tue Jul 04, 2006 10:08 pm -1100
- Location: IBP Holzkirchen, the home of WUFI
- Contact:
Hello Linda,
to stay on the save side, we most time use a initial moisture content of 80% over the whole construction. The moisture content in the case of equilibrium is lower, so with 80% you have a good information, if your construction can dry out or not. But that leads to the effect of a redistribution during the first calculated year. This is the reason why you have more moisture and thus more mould growth in the OSB during the first year.
The actual version of WufiBio uses a mean value over the calculated time period to set the traffic lights. Thats not completely right, because the traffic light was thought to interpret a time period of one year. We are working on an update for WufiBio, which will be avaliable probably next month. In this version you can choose the year of your calculation which the traffic light should interpret.
To your question about the use of WufiBio for within the construction:
In our laboratories we test how fast the mould grows under special conditions, first on highly biodegradable substrate, then, if the costumer ask for it, also on special building materials. The problem is, that it is not possible to test the building materials in the construction, because in every layer the mould conditions will be different. for example if you take your OSB-layer and put a insulation in there as the next layer. And now imagine, there are some chemicals against mould in the insulation. Probably there will be no mould, but we can not say for sure, because we don´t know all the substances for each building material. And it is impossible to test them all. So the mould check for the interior surface will probably always remain for your interpretation. But we probably will include the knowledge about mould growth (on the surface) of certain materials in later versions of WufiBio.
Best regards,
Christian
to stay on the save side, we most time use a initial moisture content of 80% over the whole construction. The moisture content in the case of equilibrium is lower, so with 80% you have a good information, if your construction can dry out or not. But that leads to the effect of a redistribution during the first calculated year. This is the reason why you have more moisture and thus more mould growth in the OSB during the first year.
The actual version of WufiBio uses a mean value over the calculated time period to set the traffic lights. Thats not completely right, because the traffic light was thought to interpret a time period of one year. We are working on an update for WufiBio, which will be avaliable probably next month. In this version you can choose the year of your calculation which the traffic light should interpret.
To your question about the use of WufiBio for within the construction:
In our laboratories we test how fast the mould grows under special conditions, first on highly biodegradable substrate, then, if the costumer ask for it, also on special building materials. The problem is, that it is not possible to test the building materials in the construction, because in every layer the mould conditions will be different. for example if you take your OSB-layer and put a insulation in there as the next layer. And now imagine, there are some chemicals against mould in the insulation. Probably there will be no mould, but we can not say for sure, because we don´t know all the substances for each building material. And it is impossible to test them all. So the mould check for the interior surface will probably always remain for your interpretation. But we probably will include the knowledge about mould growth (on the surface) of certain materials in later versions of WufiBio.
Best regards,
Christian