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Surface properties tab on MaterialsRelated TopicsRelated Topics
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Surface properties are only used in simulations when the material is located on an inner or outer surface of the construction.
Note: The absorptance values in this object impart surface properties to the construction and should be applied to the thermally significant inner and outer layers in the overall assembly. Attempting to trick the program by modelling thin “paint” layers to apply surface properties is not a good idea; the models were not intended to support such strategies.
The thermal absorptance represents the fraction of incident long wavelength radiation that is absorbed by the material. This parameter is used when calculating the long wavelength radiant exchange between various surfaces and affects the surface heat balances (both inside and outside as appropriate). Values for this field must be between 0.0 and 1.0 (with 1.0 representing “black body” conditions).
The solar absorptance field in the Material input syntax represents the fraction of incident solar radiation that is absorbed by the material. Solar radiation includes the visible spectrum as well as infrared and ultraviolet wavelengths. This parameter is used when calculating the amount of incident solar radiation absorbed by various surfaces and affects the surface heat balances (both inside and outside as appropriate). Values for this field must be between 0.0 and 1.0.
The visible absorptance field in the Material input syntax represents the fraction of incident visible wavelength radiation that is absorbed by the material. Visible wavelength radiation is slightly different than solar radiation in that the visible band of wavelengths is much more narrow while solar radiation includes the visible spectrum as well as infrared and ultraviolet wavelengths.
In EnergyPlus, this parameter is used when calculating the amount of incident visible radiation absorbed by various surfaces and affects the surface heat balances (both inside and outside as appropriate) as well as the daylighting calculations.
In Radiance daylighting simulations the surface reflectance is calculated as 1 - Visible absorptance.
Values for this field must
be between 0.0 and 1.0.
This field is a character string that defines the relative roughness of a particular material layer. This parameter only influences the the calculated exterior convection coefficient. A special keyword is expected in this field with the options being “VeryRough”, “MediumRough”, “Rough”, “Smooth”, “MediumSmooth”, and “VerySmooth” in order of roughest to smoothest options.
The colour data is used for display purposes when the texture is not available for any reason. It is not used in any of the calculations.
The texture is used to represent this material when it is specified as either the inside or outside material of a construction which is selected in the building model. It is also used to represent the material in diagrams of any construction using this material.