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Re: [EnergyPlus_Support] Re: the material input data



hi charlie
yes that is right. think in these terms. what does solar spectrum consist of? it is nothing but the UV, VISIBLE, and INFRARED. out of that the visible spectrum is the maximum. Infrared and UV are in small quantity and will come into picture when dealing with glazing. for a thermal mass material Infrared and UV are not critical. so What is there in the E+ data file is correct u can gohead with solar and visible absorptance data present in the material database.


energypluser <energypluser@xxxxxxxxxxxx> wrote:
Dear deepak

Thank you for your reply. 
I looked the folder which includes the material idf.
And I found that all the material share the same value of thermal 
absorptance. Only the solar and visible absorptance differ from one 
other.But the solar absorptance equals to the visible absorptance.
When I search the material description part of ASHREA Handbook, the 
thermal Emittance is the only available parameter. Do you know where 
I can find a handbook that is focus on the thermal properties of 
building materials?
Or how to calculate the absorptance ?
Thank you in advance

Charlie

--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "deepak kumar.c" 
<cdeepak_19@y...> wrote:
> 
> hi, I am deepak here
> Emmisivity is only the thermal emissivity in energyplus. Thermal 
absorptance what u find is energy plus is same as thermal 
emmisisvity or emmisivity. basic principle is that what ever the 
material absorps it has to emmit it back to the ambient atmosphere 
or to interiors and it is always equal to what is absorps. Emitting 
may be in any three ways of heat transfer, which depends on many 
other factors to decide which type is more happening.
>  
> If u have only emissivity that is just thermal emissivity because 
visible and solar is not expressed in terms of emisivity it will 
always be in terms of reflectance or absorptance of visible  
spectrum and solar spectrum respectively. actually speaking visible 
spectrum is a part of the solar spectrum so be careful dont try to 
derive one another by simple subtraction and addition.
>  
> If u dont know to oprn a material database file it is here
> C drive/Energyplus/Datasets/Materials
>  
> all the best
> energypluser <energypluser@y...> wrote:
> Dear all
> 
> where can I find the input data on the absorptance for thermal 
> materials ?
> What is the relationship in the thermal ,solar and visible 
absorptance?
> If I just have the emissivity of the materials, how can I get the 
three 
> absorptance based on the parameter?
> Thank you in advance
> 
> Charlie
> 
> 
> 
> 
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