3.1.1 HVAC System Map

The HVAC system in the baseline building depends on the primary building activity, the number of floors, conditioned floor area and climate zone. Details about these systems are provided in subsequent sections.

For many of the building descriptors there is a one-to-one relationship between the proposed design and the baseline building; for example, every wall in the proposed design has a corresponding wall in the baseline building. However, for HVAC systems, this one-to-one relationship generally does not hold. There may be the different number of HVAC systems serving the proposed design compared to the baseline building, and equipment such as cooling towers, circulation pumps, etc. may be present in the baseline but not proposed design.

The HVAC system in the baseline building shall be selected from Table 3, HVAC System Map, and be based on building type, number of floors, conditioned floor area, and climate zone. The selected system shall conform to the descriptions in Table 4, HVAC System Descriptions.

For systems 1, 2, 3, 4, 9, 10, 11, 12, and 13, each thermal zone shall be modeled with its own HVAC system. For systems 5, 6, 7, and 8, each floor shall be modeled with a separate HVAC system. Floors with identical thermal zones can be grouped for modeling purposes.

Table 3. HVAC System Map

Building Type Descriptions for Baseline System Definition:

• Residential

Residential buildings They 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.

• Public Assembly

Public assembly buildings include houses of worship, auditoriums, movie theaters, performance theaters, concert halls, arenas, enclosed stadiums, ice rinks, gymnasiums, convention centers, exhibition centers, museums, exercise centers and natatoriums

• Heated Only

This category applies to an entire building with heating only systems in the proposed design, such as warehouses

• Retail

Retail buildings that are two floors or less must use single-zone packaged equipment. In the baseline building, cooling will always be DX but heating will be dependent upon the climate zone. Retail buildings that are 3 or more stories are included in the Nonresidential category below. Restaurants are also included in the nonresidential category described below.

• Hospital

This excludes outpatient medical buildings and offices.

• Other Non-Residential

This category would cover all buildings that are not included any other category

Where attributes make a building eligible for more than one baseline system type, the predominant condition should be used to determine the system type for the entire building, except as notes in Section G₃.1.1. of Standard 90.1-2019 and also documented in Section 3.1.1.1 of this manual.

Table 4. HVAC System Descriptions

G3.2 New Construction/Major Alterations

The HVAC system in the baseline building depends on the primary building activity, the number of floors, conditioned floor area and climate zone. Details about these systems are provided in subsequent sections.

For many of the building descriptors there is a one-to-one relationship between the proposed design and the baseline building; for example, every wall in the proposed design has a corresponding wall in the baseline building. However, for HVAC systems, this one-to-one relationship generally does not hold. There may be a different number of HVAC systems serving the proposed design compared to the baseline building, and equipment such as cooling towers, circulation pumps, etc. may be present in the baseline but not proposed design.

The HVAC system in the baseline building shall be selected from Table 3, HVAC System Map, and be based on building type, number of floors in the building, conditioned floor area of the building type, and climate zone. The selected system shall conform to the descriptions in Table 4, HVAC System Descriptions.

For systems 1, 2, 3, 4, 9, 10, 11, 12, and 13, each thermal zone shall be modeled with its own HVAC system. For systems 5, 6, 7, and 8, each floor shall be modeled with a separate HVAC system. Floors with identical thermal zones can be grouped for modeling purposes.

Table 3. Standard 90.1 Section G3.2 HVAC System Map

Building Type Descriptions for Baseline System Definition:

• Residential

HVAC zones that include dwelling units, guest rooms, living quarters, private living spaces, and sleeping quarters. Residential associated HVAC zones shall be classified as residential. Other space types, including patient rooms in hospitals, shall not be classified as residential.

• Residential Associated HVAC Zone

Any HVAC zone that primarily includes nonresidential spaces designed to serve occupants of residential spaces, including but not limited to corridors, stairwells, elevator lobbies, and common restrooms, on a floor where over 75% of the gross conditioned floor area are residential spaces. This definition does not apply to HVAC zones within hospitals.

• Public Assembly

Public assembly buildings include houses of worship, auditoriums, movie theaters, performance theaters, concert halls, arenas, enclosed stadiums, ice rinks, gymnasiums, convention centers, exhibition centers, museums, exercise centers and natatoriums. HVAC zones that include these area types in other buildings shall also be classified as public assembly.

• Heated Only

This category applies to nonrefrigerated warehouse buildings. Ventilated parking garages that do not meet the definitions of either a conditioned or semiheated space are considered unenclosed spaces and do not apply to this category. The HVAC system types should be modeled identically in the baseline and proposed for such parking garages.

• Retail

Retail buildings that are two floors or less including grocery stories, retail stores, and supermarket buildings. Retail buildings that are 3 or more stories are included in the Nonresidential category below. Restaurants are also included in the nonresidential category described below.

• Hospital

Includes patents rooms and excludes outpatient medical buildings and offices.

• Other Non-Residential

This category covers all buildings that are not included any other categories.

Table 4. Standard 90.1 Section G3.2 HVAC System Descriptions