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 |
3.5.1 Building Orientation
|
Orientation |
|
|---|---|
|
Applicability |
All projects |
|
Definition |
The building orientation |
|
Units |
Degrees (°) |
|
Input Restrictions |
As designed |
|
Baseline Building |
The baseline building performance shall be generated by simulating the building with its actual orientation and again after rotating the entire building 90, 180, and 270 degrees, then averaging the results. The building shall be modeled so that it does not shade itself. Exceptions: a. If it can be demonstrated to the satisfaction of the Program Evaluator that the building orientation is dictated by site considerations. b. Buildings where the vertical fenestration area on each orientation varies by less than 5%. NOTE: Exception ‘a’ would need a flag on the software tool user interface, and if checked, it would need to be supported through documentation. |