3.3.7 Thermal Mass

This set of building descriptors characterize the thermal mass that is not explicitly captured by the definition of exterior surfaces and interior partitions.

Thermal Response Characteristics
Applicability	All projects
Definition	This building descriptor only addresses the building contents. The thermal mass associated with floors, interior walls, and other building envelope components is derived from the thermal properties and materials that make up these components. However, if interior partitions are not explicitly entered (see below) their effect may be captured with this input. The thermal capacitance of the building contents are typically specified in terms of the composite weight of the building contents in lb/ft² or absolute weight in lb. In this instance, the software assumes an average specific heat for the contents. This input can also be specified as the mass of the contents multiplied times the specific heat of the contents. The latter method would be a summation, since each item may have a different specific heat.
Units	lb/ft² or lb
Input Restrictions	Any reasonable inputs, consistent with the proposed design and the method used by the simulation program to model interior thermal mass
Baseline Rules	The interior thermal mass in the baseline building shall be the same as the proposed design.

Furniture and Contents
Applicability	All projects
Definition	A specification of the mass and heat capacity of furniture and other elements in the interior of the building. This includes information about the coverage and weight of furniture in the space as well as how much of the floor is covered by furniture. The latter affects how much of the solar gains that enters the space is directed to the floor with delayed heat gain and how much becomes a more instantaneous load.
Units	Data structure
Input Restrictions	Any reasonable inputs, consistent with the proposed design and the method used by the simulation program to model interior thermal mass.
Baseline Rules	The interior thermal mass and modeling assumptions in the baseline building shall be the same as the proposed design.

90.1-2019

This set of building descriptors characterize the thermal mass that is not explicitly captured by the definition of exterior surfaces and interior partitions.

Thermal Response Characteristics
Applicability	All projects
Definition	This building descriptor only addresses the building contents. The thermal mass associated with floors, interior walls, and other building envelope components is derived from the thermal properties and materials that make up these components. However, if interior partitions are not explicitly entered (see below) their effect may be captured with this input. The thermal capacitance of the building contents are typically specified in terms of the composite weight of the building contents in lb/ft² or absolute weight in lb. In this instance, the software assumes an average specific heat for the contents. This input can also be specified as the mass of the contents multiplied times the specific heat of the contents. The latter method would be a summation, since each item may have a different specific heat.
Units	lb/ft² or lb
Input Restrictions	As designed
Baseline Building	The interior thermal mass in the baseline building shall be the same as the proposed design.

Furniture and Contents
Applicability	All projects
Definition	A specification of the mass and heat capacity of furniture and other elements in the interior of the building. This includes information about the coverage and weight of furniture in the space as well as how much of the floor is covered by furniture. The latter affects how much of the solar gain that enters the space is directed to the floor with delayed heat gain and how much becomes a more instantaneous load.
Units	Data structure
Input Restrictions	As designed
Baseline Building	The interior thermal mass and modeling assumptions in the baseline building shall be the same as the proposed design.