G3.1.1 Baseline HVAC System Type and Description
|Building Area Typesa||Baseline Building Gross Above-Grade-Wall Area|
|Hotel/motel (≤75 rooms)||24%|
|Hotel/motel (>75 rooms)||34%|
|Office (≤5000 ft2)||19%|
|Office (5000 to 50,000 ft2)||31%|
|Office (>50,000 ft2)||40%|
|Restaurant (quick service)||34%|
|Restaurant (full service)||24%|
|Retail (stand alone)||11%|
|Retail (strip mall)||20%|
|School (secondary and university)||22%|
a. In cases where both a general building area type and a specific building area type are listed, the specific building area type shall apply.
|Building Area Type||Baseline Heating Method|
|Automotive facility||Gas storage water heater|
|Convenience store||Electric resistance water heater|
|Convention center||Electric resistance storage water heater|
|Courthouse||Electric resistance storage water heater|
|Dining: Bar lounge/leisure||Gas storage water heater|
|Dining: Cafeteria/fast food||Gas storage water heater|
|Dining: Family||Gas storage water heater|
|Dormitory||Gas storage water heater|
|Exercise center||Gas storage water heater|
|Fire station||Gas storage water heater|
|Grocery store||Gas storage water heater|
|Gymnasium||Gas storage water heater|
|Health-care clinic||Electric resistance storage water heater|
|Hospital and outpatient surgery center||Gas storage water heater|
|Hotel||Gas storage water heater|
|Library||Electric resistance storage water heater|
|Manufacturing facility||Gas storage water heater|
|Motel||Gas storage water heater|
|Motion picture theater||Electric resistance storage water heater|
|Multifamily||Gas storage water heater|
|Museum||Electric resistance storage water heater|
|Office||Electric resistance storage water heater|
|Parking garage||Electric resistance storage water heater|
|Penitentiary||Gas storage water heater|
|Performing arts theater||Gas storage water heater|
|Police station||Electric resistance storage water heater|
|Post office||Electric resistance storage water heater|
|Religious facility||Electric resistance storage water heater|
|Retail||Electric resistance storage water heater|
|School/university||Gas storage water heater|
|Sports arena||Gas storage water heater|
|Town hall||Electric resistance storage water heater|
|Transportation||Electric resistance storage water heater|
|Warehouse||Electric resistance storage water heater|
|Workshop||Electric resistance storage water heater|
|All others||Gas storage water heater|
|Building Type, Number of Floors, and Gross Conditioned Floor Area||Climate Zones 3B, 3C, and 4 to 8||Climate Zones 0 to 3A|
|Residential||System 1—PTAC||System 2—PTHP|
|Public assembly <120,000 ft2||System 3—PSZ-AC||System 4—PSZ-HP|
|Public assembly ≥120,000 ft2||System 12—SZ-CV-HW||System 13—SZ-CV-ER|
|Heated-only storage||System 9—Heating and ventilation||System 10—Heating and ventilation|
|Retail and 2 floors or fewer||System 3—PSZ-AC||System 4—PSZ-HP|
|Other nonresidential and 3 floors or fewer and <25,000 ft2||System 3—PSZ-AC||System 4—PSZ-HP|
|Other nonresidential and 4 or 5 floors and <25,000 ft2 or 5 floors or fewer and 25,000 ft2 to 150,000 ft2||System 5—Packaged VAV with reheat||System 6—Packaged VAV with PFP boxes|
|Other nonresidential and more than 5 floors or >150,000 ft2||System 7—VAV with reheat||System 8—VAV with PFP boxes|
1. Residential building types include dormitory, hotel, motel, and multifamily. Residential space types include guest rooms, living quarters, private living space, and sleeping quarters. Other building and space types are considered nonresidential.
2. Where attributes make a building eligible for more than one baseline system type, use the predominant condition to determine the system type for the entire building except as noted in Section G3.1.1.
4. For hospitals, depending on building type, use System 5 or 7 in all climate zones.
5. Public assembly building types include houses of worship, auditoriums, movie theaters, performance theaters, concert halls, arenas, enclosed stadiums, ice rinks, gymnasiums, convention centers, exhibition centers, and natatoriums.
|System No.||System Type||Fan Control||Cooling Typea||Heating Typea|
|1. PTAC||Packaged terminal air conditioner||Constant volume||Direct expansion||Hot-water fossil fuel boiler|
|2. PTHP||Packaged terminal heat pump||Constant volume||Direct expansion||Electric heat pump|
|3. PSZ-AC||Packaged rooftop air conditioner||Constant volume||Direct expansion||Fossil fuel furnace|
|4. PSZ-HP||Packaged rooftop heat pump||Constant volume||Direct expansion||Electric heat pump|
|5. Packaged VAV with reheat||Packaged rooftop VAV with reheat||VAV||Direct expansion||Hot-water fossil fuel boiler|
|6. Packaged VAV with PFP boxes||Packaged rooftop VAV with parallel fan power boxes and reheat||VAV||Direct expansion||Electric resistance|
|7. VAV with reheat||VAV with reheat||VAV||Chilled water||Hot-water fossil fuel boiler|
|8. VAV with PFP boxes||VAV with parallel fan-powered boxes and reheat||VAV||Chilled water||Electric resistance|
|9. Heating and ventilation||Warm air furnace, gas fired||Constant volume||None||Fossil fuel furnace|
|10. Heating and ventilation||Warm air furnace, electric||Constant volume||None||Electric resistance|
|11. SZ-VAV||Single-zone VAV||VAV||Chilled water||See note (b).|
|12. SZ-CV-HW||Single-zone system||Constant volume||Chilled water||Hot-water fossil fuel boiler|
|13. SZ-CV-ER||Single-zone system||Constant volume||Chilled water||Electric resistance|
a. For purchased chilled water and purchased heat, see G220.127.116.11.
- HVAC systems in the baseline building design shall be determined in the following order of priority:
- The building type with the largest conditioned floor area.
- Number of floors (including floors above grade and below grade but not including floors solely devoted to parking).
- Gross conditioned floor area.
- Climate zone as specified in Table G3.1.1-3. which shall conform with the system descriptions in Table G3.1.1-4. For Systems 1, 2, 3, 4, 9, 10, 11, 12, and 13, each thermal block 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 blocks can be grouped for modeling purposes.
- Use additional system types for nonpredominant conditions (i.e., residential/non- residential or heating source) if those conditions apply to more than 20,000 ft" of conditioned floor area.
- If the baseline HVAC system type is 5, 6, 7, 8, 9, 10, 11, 12, or 13 use separate single-zone systems conforming with the requirements of system 3 or system 4 (depending on building heating source) for any spaces that have occupancy or process loads or schedules that differ significantly from the rest of the building. Peak thermal loads that differ by 10 Btu/h-ft2 or more from the average of other spaces served by the system, or schedules that differ by more than 40 equivalent full-load hours per week from other spaces served by the system, are considered to differ significantly. Examples where this exception may be applicable include but are not limited to natatoriums and continually occupied security areas. This exception does not apply to computer rooms.
- For laboratory spaces in a building having a total laboratory exhaust rate greater than 15,000 cfm, use a single system of type 5 or 7 serving only those spaces. The lab exhaust fan shall be modeled as constant horsepower reflecting constant- volume stack discharge with outdoor air bypass.
- Thermal zones designed with heating-only systems in the proposed design serving storage rooms, stairwells, vestibules, electrical/mechanical rooms, and restrooms not exhausting or transferring air from mechanically cooled thermal zones in the proposed design shall use system type 9 or 10 in the baseline building design.
- If the baseline HVAC system type is 9 or 10, all spaces that are mechanically cooled in the proposed design shall be assigned to a separate baseline system determined by using the area and heating source of the mechanically cooled spaces.
- Computer rooms in buildings with a total computer room peak cooling load >3,000,000 Btu/h or a total computer room peak cooling load >600,000 Btu/h where the baseline HVAC system type is 7 or 8 shall use System 11. All other computer rooms shall use System 3 or 4.
- For hospitals, depending on building type, use System 5 or 7 in all climate zones.
For systems using purchased hot water or steam, the heating source shall be modeled as purchased hot water or steam in both the proposed design and baseline building design. Hot-water or steam costs shall be based on actual utility rates, and on-site boilers, electric heat, and furnaces shall not be modeled in the baseline building design.
G18.104.22.168 Baseline HVAC System Requirements for Systems Utilizing Purchased Chilled Water and/or Purchased Heat
If the proposed design uses purchased heat, but does not use purchased chilled water, then Tables G3.1.1-3 and G3.1.1-4 shall be used to select the baseline HVAC system type, and purchased heat shall be substituted for the heating type in Table G3.1.1-4. The same heating source shall be used in the proposed design and baseline building design.
If the proposed design uses purchased chilled water but does not use purchased heat, then Tables G3.1.1-3 and G3.1.1-4 shall be used to select the baseline HVAC system type, with the modifications listed below:
- Purchased chilled water shall be substituted for the cooling types in Table G3.1.1-4.
- System 1 and 2 shall be constant-volume fan-coil units with fossil fuel boilers.
- System 3 and 4 shall be constant-volume single-zone air handlers with fossil fuel furnaces.
- System 7 shall be used in place of System 5.
- System 8 shall be used in place of System 6.
All on-site distribution pumps shall be modeled in both the proposed design and base building design.
The air leakage rate of the building envelope I75Pa at a pressure differential of 0.3 in. of water shall be converted to appropriate units for the simulation program using one of the following formulas:
For methods describing air leakage as a function of floor area,
IFLR = 0.112 × I75Pa × S/AFLR
IAGW = 0.112 × I75Pa × S/AAGW
I75Pa = Q/S
|I75pa||=||air leakage rate of the building envelope (cfm/ft2) at a fixed building pressure differential of 0.3 in. of water, or 1.57 psf|
|Q||=||volume of air in cfm flowing through the building envelope when subjected to a pressure differential of 0.3 in. of water, or 1.57 psf, in accordance with ASTM E 779|
|S||=||total area of the building envelope (ft2), including the lowest floor, any below-grade walls or above-grade walls, and roof (including vertical fenestration and skylights)|
|IFLR||=||adjusted air leakage rate of the building envelope (cfm/ft2) at a reference wind speed of 10 mph and relative to the gross floor area|
|AFLR||=||gross floor area, ft2|
|IAGW||=||adjusted air leakage rate of the building envelope (cfm/ft2) at a reference wind speed of 10 mph and relative to the area of the above-grade walls of the building envelope|
|AAGW||=||total area of above-grade walls of the building envelope, ft2|