3.3.1 General Information

Thermal Block Name
Applicability	All projects
Definition	A unique identifies for the thermal block
Units	Text
Input Restrictions	None
Baseline Rules	Not applicable

Thermal Block Description
Applicability	All projects
Definition	A brief description of the thermal block that identifies the spaces and/or zones that make up the thermal block or other descriptive information. The description should tie the thermal block to the building plans.
Units	Text
Input Restrictions	None
Baseline Rules	Not applicable

Thermal Block Type

Applicability

All projects

Definition

Designation of the thermal block as directly conditioned space, semiheated, indirectly conditioned space (i.e., conditioned only by borrowed heating or cooling from an adjacent thermal block), unconditioned space, or plenum (i.e., unoccupied but partially conditioned as a consequence of its role as a path for returning air).

Conditioned Space: Is a space that has a heating and/or cooling system of sufficient size to maintain temperatures suitable for human comfort. a cooled space, heated space, or indirectly conditioned space defined as follows:
Cooled Space: an enclosed space within a building that is cooled by a cooling whose sensible output capacity exceeds 5 Btu/h·ft² of floor area.
Heated space: an enclosed space within a building that is heated by a heating system whose output capacity relative to the floor area is greater than or equal to the values below.

Climate Zone	Heating Output (Btu/h·ft²)
1 and 2	5
3	10
4 and 5	15
6 and 7	20
8	25

Indirectly Conditioned Space: an enclosed space within a building that is not a heated space or a cooled space, which is heated or cooled indirectly by being connected to adjacent space(s) provided:
the product of the U-factor(s) and surface area(s) of the space adjacent to connected space(s) exceeds the combined sum of the product of the U-factor(s) and surface area(s) of the space adjoining the outdoors unconditioned spaces, and to or from semiheated spaces (e.g., corridors) or
that air from heated or cooled spaces is intentionally transferred (naturally or mechanically) into the space at a rate exceeding 3 ach (e.g., atria).
Semi-Heated Space: an enclosed space within a building that is heated by a heating system whose output capacity is greater than or equal to 3.4 Btu/h·ft² of floor area but is not a conditioned space.
Unconditioned Space: an enclosed space within a building that is not a conditioned space or a semi heated space. Crawlspaces, attics, and parking garages with natural or mechanical ventilation are not considered enclosed spaces.

Units

List: directly conditioned, indirectly conditioned, semiheated, unconditioned or plenum

Input Restrictions

The default thermal block type is “directly conditioned.”

Baseline Rules

The descriptor is identical for proposed design and baseline building.

System Name
Applicability	All projects
Definition	The name of the HVAC system that serves this thermal block. This is the link between the thermal block and an HVAC system. The purpose of this building descriptor is to link the thermal zone to a system (child points to parent). Software can make this link in other ways.
Units	Text, unique
Input Restrictions	None
Baseline Rules	The baseline building HVAC system may be different from the rated building and thermal blocks may be mapped differently. Baseline system types 1-4 and 9-13 are required to have one system per thermal zone. Baseline system types 5-8 are required to be one system per floor.

Occupancy Type
Applicability	All projects
Definition	One of three occupancy categories used in determining the baseline building envelope requirements. The three categories are residential, nonresidential, and semi-heated.
Units	List: residential, nonresidential, or semi-heated
Input Restrictions	The input shall be consistent with the building classification and the classifications of the spaces that make up the thermal block.
Baseline Rules	Same as the proposed design

Floor Area
Applicability	All projects
Definition	The gross floor area of a thermal block including wall thicknesses and minor spaces for mechanical or electrical services, such as chases, that are not assigned to other thermal blocks. Larger mechanical spaces and electrical rooms should not be combined.
Units	Square feet (ft²)
Input Restrictions	The floor area of the thermal block is derived from the floor area of the individual spaces that make up the thermal block.
Baseline Rules	Same as the proposed design

90.1-2019

Thermal Block Names
Applicability	All projects
Definition	A unique identifier for the thermal zone.
Units	Text
Input Restrictions	None
Baseline Building	Not applicable

HVAC Zone Associated Building Area Types
Applicability	All projects
Definition	An associated building area type for each HVAC zone. The permitted building area types are restricted to the building area types defined in Standard 90.1-2019 Section 9.5.1. This mapping is used to identify the baseline HVAC system, baseline SHW system and the WWR for the baseline building.
Units	Text
Input Restrictions	HVAC zones in the proposed building model shall be assigned to a building area type.
Baseline Building	Same as proposed

HVAC Zone Description
Applicability	All projects
Definition	A brief description of the HVAC zone that identifies the spaces that makes up the HVAC zone or other descriptive information. The description should tie the HVAC zone to the building plans.
Units	Text
Input Restrictions	HVAC zones in the proposed building model shall match those in the proposed building design, with each temperature control device defining a separate thermal zone. Refer to Section 2.3 of this manual for guidance on how to define thermal blocks, HVAC zones, and spaces.
Baseline Building	Same as proposed

Space Conditioning Category

Applicability

All projects

Definition

Designation of the zone as containing a directly conditioned space, semi-heated, unconditioned, or plenum (i.e., unoccupied but partially conditioned as a consequence of its role as a path for returning air).

Conditioned Space: a space that has a heating and/or cooling system of sufficient size to maintain temperatures suitable for human comfort. Cooled zone, heated space, and indirectly conditioned space are defined as follows:

• Cooled space: an enclosed space within a building that is cooled by a cooling system whose sensible output capacity is greater than or equal to 3.4 Btu/h·ft2 of floor area.

• Heated space: an enclosed space within a building that is heated by a heating system whose output capacity relative to the floor area is greater than or equal to the criteria in Table 11.

• Indirectly conditioned space: an enclosed space within a building that is not a heated space or a cooled space, which is heated or cooled indirectly by being connected to adjacent space(s) provided:

The product of the U-factor(s) and surface area(s) of the space adjacent to connected space(s) exceeds the combined sum of the product of the U-factor(s) and surface area(s) of the space adjoining the outdoors, unconditioned spaces, and to or from semi-heated spaces (e.g., corridors) or

That air from heated or cooled spaces is intentionally transferred (naturally or mechanically) into the space at a rate exceeding 3 air changes per hour (ACH) (e.g., atria).

Semi-Heated Space: an enclosed space within a building that is heated by a heating system whose output capacity is greater than or equal to 3.4 Btu/h·ft2 of floor area but is not a conditioned space.

Unconditioned space: an enclosed space within a building that is not a conditioned space or a semi-heated space.

NOTE: Crawlspaces, attics, and parking garages with natural or mechanical ventilation are not considered enclosed spaces. Rules for unconditioned spaces, not considered enclosed, are documented in Section 2.4.3 of this document.

Table 11. Standard 90.1-2019 Heated Space Criteria

Heating Output (Btu/h-ft²⁾	Climate Output
>5	0,1, and 2
>9	3A, 3B
>7	13A, 3B
>10	4A, 4B
>8	4C
>12	5
>14	6
>16	7
>19	8

Units

List: Conditioned, Semi-heated, and Unconditioned

Input Restrictions

As designed except spaces designed as semi-heated that are not storage, stairwells, vestibules, electrical/mechanical rooms or restrooms, shall be modeled as a cooled space. The cooling system type shall be the same as the modeled in the baseline building design and shall comply with requirements specified in Standard 90.1-2019 Section 6.

Baseline Building

Same as proposed for all space types except when spaces are designated as semi-heated spaces in the proposed or baseline building. The criteria for a semi-heated space must be verified in both the baseline building and the proposed building.

For spaces in the proposed building, the following should be verified:

• The heating temperature setpoint is always < 60°F, and

• The proposed system capacity falls within the limits for a semi-heated space.

If these conditions are met, the spaces are designated as semi-heated for the proposed building, and baseline building sizing runs in accordance with Section Error! Reference source not found. are carried out where the space in the baseline building is simulated with semi-heated envelope requirements to verify heating and cooling system capacity.

If the heating system output capacity is greater than or equal to the values in Table 11 and the cooling capacity is greater than 5 Btu/h·ft2 , then the space is considered conditioned in the baseline building and should be analyzed with the conditioned envelope requirements in Standard 90.1 Tables G3.4-1 to Tables G3.4-8. If the heating or cooling capacity falls within the range of a semi-heated space, the space is considered a semi-heated space and the baseline building sizing run is complete.

Table 12. Heated Space Criteria for the Baseline Building

Heating Output (Btu/h·ft2 )	Climate Zone
>5	0,1, and 2
>10	3
>15	4,5
>20	6,7
>25	8

HVAC Zone Type
Applicability	All projects
Definition	Designation of the thermal zone as directly conditioned, semi-heated, indirectly conditioned (i.e., conditioned only by passive heating or cooling from an adjacent thermal zone), or plenum (i.e., unoccupied but partially conditioned as a consequence of its role as a path for returning air). A thermal zone may include a single space or more than one space. Each thermal zone shall have a single temperature control device.
Units	List: Directly Conditioned, Indirectly Conditioned, Semi-Heated, Unconditioned or Plenum
Input Restrictions	The default thermal zone type is “directly conditioned”
Baseline Building	The descriptor is identical for the proposed design and baseline building

Occupancy Type
Applicability	All projects
Definition	Separate exterior building envelope requirements are specified for each of three categories of conditioned space: (a) nonresidential conditioned space, (b) residential conditioned space, and (c) semi-heated space. • Non-residential space conditioning category: all occupancies other than residential. • Residential space conditioning categories: spaces in buildings used primarily for living and sleeping. Residential spaces include, but are not limited to, dwelling units, hotel/motel guest rooms, dormitories, nursing homes, patient rooms in hospitals, lodging houses, fraternity/sorority houses, hostels, prisons, and fire stations. • Semi-heated: spaces that meet the semi-heated space criteria.
Units	Text, unique
Input Restrictions	As designed
Baseline Rules	Same as proposed for all space types except semi-heated. A sizing run, with semi-heated envelope construction properties, would need to be done to determine heating capacity per unit area for the baseline building.

Ventilation System Name
Applicability	All projects
Definition	The name of the system that provides ventilation to the thermal zone. In most cases, the primary heating/cooling system provides the required ventilation air. For thermal zones served by a dedicated outdoor air system, this descriptor would be used to identify the same. The purpose of this building descriptor is to link the thermal zone to a system.
Units	Text, unique
Input Restrictions	None
Baseline Building	N/A

Primary Heating/ Cooling System Name
Applicability	All projects
Definition	The name of the primary HVAC system that serves this thermal zone. The purpose of this building descriptor is to link the thermal zone to a system. For thermal zones served by a ventilation system like a dedicated outdoor air system (DOAS) and a separate HVAC system that meets the heating and cooling loads, the DOAS system would be defined as the ventilation system and the HVAC system would be defined as the primary heating/cooling system.
Units	Text, unique
Input Restrictions	None
Baseline Building	The baseline building may have a different system mapping if the baseline building has a different HVAC type than the proposed design. Baseline system types 5-8 are required to be one system per floor. This could result in different system names as well.

Primary Heating/ Cooling System Name
Applicability	All projects
Definition	The name of the primary HVAC system that serves this thermal zone. The purpose of this building descriptor is to link the thermal zone to a system. For thermal zones served by a ventilation system like a dedicated outdoor air system (DOAS) and a separate HVAC system that meets the heating and cooling loads, the DOAS system would be defined as the ventilation system and the HVAC system would be defined as the primary heating/cooling system.
Units	Text, unique
Input Restrictions	None
Baseline Building	The baseline building may have a different system mapping if the baseline building has a different HVAC type than the proposed design. Baseline system types 5-8 are required to be one system per floor. This could result in different system names as well.

Secondary Heating/ Cooling System Name
Applicability	All projects
Definition	The name of the secondary HVAC system that serves this thermal zone. This descriptor is used if more than one HVAC system serves a thermal zone. For example a VAV with perimeter baseboards. The baseboards would be the secondary system. The purpose of this building descriptor is to link the thermal zone to a system.
Units	Text, unique
Input Restrictions	None
Baseline Building	N/A

Floor Areas
Applicability	All projects
Definition	The gross floor area of a thermal zone, including walls and minor spaces for mechanical or electrical services such as chases not assigned to other thermal zones
Units	Square feet (ft²)
Input Restrictions	The floor area of the thermal zone is derived from the floor area of the individual spaces that make up the thermal zone
Baseline Building	Same as proposed