2D:DialogEditMaterial

Dialog: Edit Material

In this dialog you can view or edit the material data for the selected element of the building component.

For a detailed discussion of the material data, please consult the topic Material Data.

• The Unlock Icon:

Unlock the material to edit it. Once the material has been unlocked, an asterisk to the left of its name indicates that it may not be identical any more with the original material from the database, as it may have been edited.
 

• "Material Name":

The name of the material.
An asterisk to the left of the material name indicates that it has been unlocked and may not be identical any more with the original material from the database (see above).
 

• "Basic Values"
  
  • "Bulk Density [kg/m³]",
    
  • "Porosity [m³/m³]",
    
  • "Spec. Heat Capacity [J/kgK]",
    
  • "Thermal Conductivity dry [W/mK]",
    
  • "Water Vapor Diffusion Resistance Factor dry [-]":
    

These basic material data are required as a minimum for a calculation.
 

• "Generation Parameters":

Some of the material data in the section "Hygric Extensions" (see below) are difficult to acquire, but WUFI offers means generate them from standard data which can be collected more easily. These standard data are then "Generation Parameters"; which of them are required for this material depends on the settings in the "Hygric Extensions" dialog.
 
The generation parameters are discussed in the respective topics of the "Hygric Extensions" section.
 

• "Additionals"
  • "Color":
    Select the color of the material for the graphical component display.
     
    
  • "Typical Built-In Moisture [kg/m³]":
    A typical application for WUFI is a calculation to determine the time it takes a newly-built wall to dry out. If a typical initial moisture content for the current material is known, you can enter it here to look it up later when you need it.
     
    
• "Hygric Extensions":
  Enter the hygric material data in these tables (if required).
   
  The hygric extensions comprise the moisture storage function of the material, the liquid transport coefficients, the moisture-dependent thermal conductivity and the moisture-dependent vapor diffusion resistance factor.
   
  The hygric extensions are always entered in tables. However, you can have WUFI automatically create some of these tables by entering other related data from which the tables can be generated.
   
  
  • "Moisture Storage Function":
    Enter the moisture storage function of the material, i.e. the moisture contents [kg/m³] which result from exposition to different relative humidities (0..1).
     
    If detailed tabulated data are not available, but the moisture storage function of the material can be adequately described by an approximation function, you can check the option "Generate" and enter in the section "Generation of the Moisture Storage function"
     
    
    • the sorption moisture corresponding to RH 0.8, w80 ("Reference Water Content [kg/m³]", as determined according to German standard DIN 52620),
    • the "Free Water Saturation [kg/m³]" wf and
      
    • RH and water content for a third point if you selected the "Enhanced" approximation function.
       
      WUFI then uses an analytical moisture storage function which passes through these two or three points and the zero point.
       
      For non-hygroscopic materials, just leave the table of the moisture storage function empty. For numerical reasons, however, WUFI needs a defined moisture storage function for all materials; it then internally uses a default function which allows for the very low sorption moisture of non-hygroscopic materials. For details on this default moisture storage function see the Questions & Answers section.
       
      
  • "Liquid Transport Coefficient"
    Enter the liquid transport coefficients in this table - separately for suction and redistribution.
     
    If the liquid transport coefficients for the material at hand are not known, you can have WUFI automatically generate a table by estimating the coefficients from the water absorption coefficient (A-value) which is known for most materials or is at least easily measurable.
     
    To this end, check the option "Generate" and enter the A-value in the section "Generation Parameters" (in [kg/m²s^1/2]; the relevant German standard uses the non-SI units [kg/m²h^1/2]. Division by 60 converts such values to SI). WUFI automatically generates a three-line table with the corresponding estimated liquid transport coefficients.
     
    Please note that only a rough estimate is possible which proves successful in many cases, but which is not necessarily useful for all materials. Especially, there may be inaccuracies in the shape of the suction profiles. Generating is just meant to be some assistance; you should not blindly rely on it. Future WUFI versions are planned to offer more sophisticated methods.
     
    Remarks on generating:
    
    • The estimate of the liquid transport coefficients from the A-value also uses the moisture contents [[Details:MoistureStorageFunction | w80 and wf.
      If the moisture storage function is being approximated from w80 and wf (see above), the two values are directly taken from these two entries; otherwise they are calculated from the corresponding table - by interpolation, if necessary.
      
    • If no moisture storage function has been defined yet, generating is not possible - the table remains empty (but you can already enter the A-value).
      
    • If the moisture storage function is modified after generating, the generated table adapts automatically. Please note, therefore, that modification of a material property can also change another property as a side effect without this being immediately evident.
      
    • If you want to generate both the tables for suction and those for redistribution, both must of course be derived from the same A-value - the two tables therefore share this text box. Note that here, too, a modification intended to change one coefficient may entail changes in the other one (if you are generating only one of the tables and editing the other one by hand, the non-generated table is not affected by a modification of the water absorption factor, of course).
       
      
  • "Thermal Conductivity, Moisture-dependent":
    Enter the heat conductivity of the material as a function of its moisture content if you want to allow for its moisture-dependent variability.
     
    If you are satisfied with a simple linear dependence of the heat conductivity on the moisture content, you can have WUFI automatically generate a two-line table by entering the moisture-induced heat conductivity supplement.
     
    To this end, check the option "Generate" and enter the supplement in the section "Generation Parameters" (in [%/mass-%]). WUFI automatically generates a two-line table with the heat conductivities resulting for the dry condition and the maximum water content. Heat conductivities for intermediate moisture contents are linearly interpolated during the calculation.
     
    Remarks on Generating:
    
    • The evaluation of the heat conductivity for maximum water content also uses the basic material properties bulk density, porosity and heat conductivity dry. If these values are modified after generating, the generated table adapts automatically.
      Please note, therefore, that modification of a material property can also change another property as a side effect without this being immediately evident.
      
    • If the required basic material data have not all been defined yet, generating is not possible - the table remains empty (but you can already enter the supplement).
       
      
  • "Water Vapor Diffusion Resistance Factor, Moisture-dependent":
    Enter the diffusion resistance factor of the material as a function of moisture content if you want to allow for its moisture-dependent variability.
     
    General remarks on generating:
    For all hygric material properties - except the diffusion resistance factor - WUFI is holding two tables in memory: one table created by hand (editable), and one generated table (non-editable). You can work on both tables in parallel; which of both is used for the calculation depends on whether the option "Generate" is activated at the start of the calculation, or not.
    By activating or deactivating the option, you can switch between the two kinds of tables. The unused table remains inactive in background.
     
    
  • "Info"
    The info text provides additional information about the material, such as sources of the data, peculiarities of the material etc.
     
    
  • "Details"
    This tab will provide features used by future versions of WUFI-2D. Currently, WUFI-2D ignores them.