General tab on Materials Dialog.
Materials are used to define the properties of construction layers. There are 2 types of material:
Detailed properties including the thermophysical properties, surface properties and visual appearance for the material.
Simple resistive material with no thermal mass. This option will typically be used to model air gaps.
This field is used to enter the thermal conductivity of the material layer. Thermal conductivity must be greater than zero.
This field represents the specific heat of the material layer. Only positive values of specific heat are allowed.
This field is used to enter the density of the material layer. Density must be a positive quantity.
This field is used to enter the thermal resistance (R-value) of the material layer.
Note: Materials defined using an R-value do not contribute to construction (and hence building) thermal mass in the calculations and so should be used with care, especially if you plan to use the model for dynamic thermal simulations.
Surface properties are only used in simulations when the material is located on an inner or outer surface of the construction.
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. 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. 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.