3.5.1 Materials

Energy simulation programs commonly define construction assemblies by listing a sequence of materials that make up that construction assembly. Appendix D has a list of standard materials that may be referenced by construction assemblies. Additional materials not listed in Appendix D may be defined as described below. Alternate methods may be used to define construction assemblies such as specifying the U-factor and optionally, a metric describing thermal mass such as heat capacity (HC). These alternate methods may not require identification of materials. When a material is defined, all of the properties listed below must be defined. Some materials listed in Appendix D are non-homogeneous, for instance, framing members with insulation in the cavity.

Material Name

Applicability

When construction assemblies reference materials that are not standard

Definition

The name of a construction material used in the exterior envelope of the building

Units

Text, unique

Input Restrictions

Material name is a required input for materials not available from the standard list. The user may not modify entries for predefined materials.

Baseline Rules

Not applicable

 

Density

Applicability

All non-standard materials

Definition

The density (or mass per unit of volume) of the construction material as documented in an ASHRAE handbook, a comparably reliable reference, or manufacturers’ literature.

Units

Numeric input: lb/ft3

Input Restrictions

Density is a required input when non-standard materials are specified.

Baseline Rules

Not applicable

 

Specific Heat

Applicability

All non-standard materials

Definition

The specific heat capacity of a material is numerically equal to the quantity of heat that must be supplied to a unit mass of the material to increase its temperature by 1 degree F.

Units

Btu/lb•°F

Input Restrictions

Specific heat is a required input when non-standard materials are specified. The specific heat capacity of the construction material as documented in an ASHRAE handbook, a comparably reliable reference, or manufacturers’ literature.

Baseline Rules

Not applicable

 

Thermal Conductivity

Applicability

All non-standard materials

Definition

The thermal conductivity of a material of unit thickness is numerically equal to the quantity of heat that will flow through a unit area of the material when the temperature difference through the material is 1 degree F.

Units

Btu/h•ft•°F

Input Restrictions

Thermal conductivity is a required input for non-standard materials.

Baseline Rules

Not applicable

 

Thickness

Applicability

All non-standard materials

Definition

The thickness of a material

Units

ft or in. (cm)

Input Restrictions

Thickness is a required input for non-standard materials. The user shall document the data source for thermal conductivity used for additional materials under the material name descriptor.

Baseline Rules

Not applicable

Building EQ


 

Energy Star