General tab on Materials Dialog.
Materials are used to define the properties of construction layers. There are 2 types of material:
If the material should only be used in layers of a particular thickness then check this box and enter the material thickness that applies below. When materials having this option set are selected on the Constructions dialog the layer thickness will be fixed with the material thickness described below.
This option may be useful for materials such as bricks, tiles, insulation and PCMs which are usually supplied with a particular thickness.
The fixed layer thickness of the material (in m or in) when selected.
This should be the dimension of the layer in the direction perpendicular to the main path of heat conduction. Modelling layers thinner (less) than 0.003 m is not normally recommended; rather, add those properties to one of the adjacent layers.
This field is used to enter the thermal conductivity of the material layer. Thermal conductivity must be greater than zero.
This field is used to enter the thermal conductivity of the material layer (in W/m-K or Btu-in/h-ft2-F). Thermal conductivity must be greater than zero. Modelling layers with conductivity higher than 5.0 W/(m-K) is not normally recommended.
This field represents the specific heat of the material layer (in J/kg-K or Btu/lb-F).
Note: EnergyPlus uses scientific SI units but data reported in textbooks and references will often use kJ/kg-K or J/g-K instead. Take care!
Only values of specific heat of 100 or larger are allowed. Typical ranges are from 800 to 2000 J/kg-K.
This field is used to enter the density of the material layer in (kg/m3 or lb/ft3). Density must be a
positive quantity.
Note: Some textbooks and references may use units of g/m3. Take care!
This field is used to enter the thermal resistance (R-value) of the material layer (in m2-K/W or ft2-F-hr/Btu).
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. You are especially advised not to use R-value materials on the innermost layer of constructions and you should not generally use them for representing materials that have mass. They are best used for modelling air gaps and insulation layers.
You can enter vapour diffusion properties here if the material is to be used within a construction which is have a condensation analysis carried out. Otherwise this data does not have to be entered for general simulations.
Note: The moisture diffusion data provided in the literature tends to be very approximate, much more so than for thermal properties. This is due to large variations in these properties that have been measured in lab tests.
There are 3 ways to define the vapour diffusion properties of the material:
Enter the vapour factor for the material. There are no units.
Enter the vapour resistivity (in MNs/g).