This group of building descriptors relate to the secondary HVAC systems. There is not a one-to-one relationship between secondary HVAC system components in the proposed design and the baseline building since the baseline building system is determined from building type, size and heating source. Appendix A shows the applicability of each building descriptor for the eight baseline building systems. Depending on the nature of the proposed design, any of the building descriptors could apply.
This group of building descriptors relate to the secondary HVAC systems. There is not a one-to-one relationship between secondary HVAC system components in the proposed design and the baseline building since the baseline building system is determined from building type, size and heating source. See Table 3.1-1, 3.1-2 and 3.1-3. Additional detail on the baseline building systems is provided in the tables below. Depending on the nature of the proposed design, any of the building descriptors could apply.
Table 3.7-1: Baseline Building System Type
|
Baseline Building System |
System Type |
|
System 1 – PTAC |
Single Zone Heating and Cooling |
|
System 2 – PTHP |
Single Zone Heating and Cooling |
|
System 3 – PSZ-AC |
Single Zone Heating and Cooling |
|
System 4 – PSZ-HP |
Single Zone Heating and Cooling |
|
System 5 – Packaged VAV with Reheat |
Single Duct VAV |
|
System 6 – Packaged VAV with PFP boxes |
Single Duct VAV |
|
System 7 – VAV with Reheat |
Single Duct VAV |
|
System 8 – VAV with PFP boxes |
Single Duct VAV |
|
System 9 – Heating and Ventilation |
Constant Volume Heat/Vent (no cooling) |
|
System 10 – Heating and Ventilation |
Constant Volume Heat/Vent (no cooling) |
|
System 11. SZ–VAV |
Single-zone VAV |
|
System 12. SZ-CV-HW |
Single zone with hot water heat |
|
System 13. SZ-CV-ER |
Single zone with electric resistance heat |
Table 3.7-2: Summary of Baseline Building Secondary HVAC System Properties
|
System |
Fan Control |
Economizer |
Cooling Type |
Cooling Efficiency. |
Minimum Supply T. |
Heating Type |
Heating Efficiency |
Maximum Supply T. |
|
1 PTAC |
Constant volume |
Not required |
Direct Expansion |
Minimum SEER or EER based on equipment type and output capacity of proposed unit(s). Adjusted EER is calculated to account for supply fan energy. |
20 °F below occupied space cooling setpoint |
Hot-water fossil fuel boiler |
Minimum AFUE, Thermal Efficiency, COP or HSPF based on equipment type and output capacity of baseline unit(s). |
|
|
2 PTHP |
Electric heat pump |
|||||||
|
3 PSZ-AC |
Integrated economizer with dry-bulb high limit by climate zone. See 6.7.4 ‘Outside Air Controls and Economizer’ for details and exceptions. |
Fossil fuel furnace |
||||||
|
4 PSZ-HP |
Electric heat pump |
|||||||
|
5 PVAV |
Variable volume |
Hot-water fossil fuel boiler |
||||||
|
6 PVAV / PFP |
Electric resistance |
|||||||
|
7 VAV |
Chilled water |
See 6.8 Primary Systems |
Hot-water fossil fuel boiler |
|||||
|
8 VAV / PFP |
Electric resistance |
|||||||
|
9 HV Furnace |
Constant volume |
Not required |
None |
None |
Fossil fuel furnace |
|||
|
10 HV Electric |
Electric resistance |
|||||||
|
11 SZ-VAV |
Variable volume |
Integrated economizer with dry-bulb high limit by climate zone. See 6.7.4 for details. |
Chilled water |
See 6.8 Primary Systems |
See note. |
|||
|
12 SZ-CV-HW |
Constant Volume |
Hot-water fossil fuel boiler |
||||||
|
13 SZ-CV-ER |
Electric resistance |
Table 3.7-3: Summary of Baseline Building Variable Volume Fan Control and Reheat
|
Code |
Supply Fan Control |
PFP Fan |
Reheat Terminal Flow |
|
|
5 PVAV |
Variable speed controlled by variable speed drives. The part load performance of VAV fans is required to be modeled in accordance to section ‘Fan Part Load Curve’ in ‘Fan Systems’. |
|
Minimum volume setpoint for reheat is highest of 30% of zone peak flow, minimum outdoor air flow rate or airflow rate required by applicable rating authority. See Section 3.6.5 for details |
|
|
6 PVAV / PFP |
PIU fan would be constant volume. AHU fan should cycle on only for cooling. Zone fans should provide unoccupied heating. |
Fans for PIU units are sized for 50% of peak design primary air |
||
|
7 VAV |
|
|
||
|
8 VAV / PFP |
PIU fan would be constant volume. AHU fan should cycle on only for cooling. Zone fans should provide unoccupied heating. |
Fans for PIU units are sized for 50% of peak design primary air |
||
This group of building descriptors relate to the secondary HVAC systems. There is not a one-to-one relationship between secondary HVAC system components in the proposed design and the baseline building since the baseline building system is determined from building type, size, and heating source. Depending on the nature of the proposed design, any of the building descriptors could apply.
The HVAC baseline systems are described in the summary tables below for reference. The details of individual building descriptor definitions can be found in Sections 3.8 and 3.9.
Table 41. System 1 and System 2 Descriptions
|
System Description |
Packaged terminal air conditioner (#1) or packaged terminal heat pump (#2) |
|
Supply Fan Power |
Fan power integral to unit efficiency. Fan power = 0.3 ´ cfms. Refer to building descriptor Fan Systems. Ventilation is provided through the system. |
|
Supply Fan Control |
Constant volume |
|
Min Supply Temp |
20°F below occupied space cooling setpoint |
|
Cooling System |
DX |
|
Cooling Efficiency |
Minimum seasonal energy efficiency ratio (SEER) or EER based on equipment type and output capacity of proposed unit(s). Adjusted EER is calculated to account for supply fan energy. |
|
Maximum Supply Temp |
20°F above occupied space heating setpoint |
|
Heating System |
Hot water boiler (#1) or heat pump (#2) |
|
Heating Efficiency |
Minimum annual fuel utilization efficiency (AFUE), thermal efficiency, COP, or heating seasonal performance factor (HSPF) based on equipment type and output capacity of baseline unit(s) |
|
Economizer |
None |
|
Ducts |
N/A (not ducted) |
Table 42. System 3 and System 4 Descriptions
|
System Description |
Packaged single zone with gas furnace/electric air conditioning (#3) or heat pump (#4) |
|
Supply Fan Power |
See building descriptor Fan Systems, Section 3.7.3 of this document |
|
Supply Fan Control |
Constant volume |
|
Min Supply Temp |
20°F below occupied space cooling setpoint |
|
Cooling System |
DX |
|
Cooling Efficiency |
Minimum SEER or EER based on equipment type and output capacity of baseline unit(s). Adjusted EER is calculated to account for supply fan energy. |
|
Maximum Supply Temp |
20°F above occupied space heating setpoint |
|
Heating System |
Fossil fuel furnace (#3) or heat pump (#4) |
|
Heating Efficiency |
Minimum AFUE, thermal efficiency, COP, or HSPF based on equipment type and output capacity of baseline unit(s) |
|
Economizer |
Integrated economizer with dry-bulb high limit by climate zone. Refer to building descriptor Outside Air Controls and Economizer, Section 3.7.4, for details. |
Table 43. System 5 Description
|
System Description |
Packaged VAV with DX cooling, fossil fuel boiler and hot-water reheat |
|
Supply Fan Power |
See building descriptor Fan Systems, Section 3.7.3 of this document |
|
Supply Fan Control |
|
|
Return Fan Control |
Same as supply fan |
|
Minimum Supply Temp |
20°F below occupied space cooling setpoint |
|
Supply Temp Control |
The air temperature for cooling shall be reset higher by 5°F under minimum cooling load conditions. This strategy is described in Section 3.7.2.2 of this document. |
|
Cooling System |
DX |
|
Cooling Efficiency |
Minimum efficiency based on average output capacity of equipment unit(s) |
|
Maximum Supply Temp |
20°F above occupied space heating setpoint |
|
Heating System |
Hot water boiler, with hot water (HW) reheat |
|
Reheat Terminal Airflow |
System 5: Minimum volume setpoint for reheat is highest of 30% of zone peak flow, minimum outdoor airflow rate or airflow rate required by applicable rating authority. See Section 3.7.5 for details. |
|
Hot Water Pumping System |
The pumping system shall be modeled as primary-only with continuous variable flow and a minimum of 25% of the design flow rate. Hot-water systems serving 120,000 ft2 or more shall be modeled with variable-speed drives, and systems serving less than 120,000 ft2 shall be modeled as riding the pump curve. See Section 3.8.5 of this document for details. |
|
Heating Efficiency |
Minimum efficiency based on average output capacity of baseline equipment unit(s) |
|
Economizer |
Integrated economizer with dry-bulb high limit by climate zone. Refer to building descriptor Outside Air Controls and Economizer, Section 3.7.4, for details. |
Table 44. System 6 Description
|
System Description |
Packaged VAV, with DX cooling, electric heating and parallel fan-powered boxes with electric heat |
|
|
Supply Fan Power |
See building descriptor Fan Systems, Section 3.7.3 of this document |
|
|
Supply Fan Control |
|
|
|
Return Fan Control |
Same as supply fan |
|
|
Minimum Supply Temp: |
20°F below occupied space cooling setpoint |
|
|
Supply Temp Control |
The air temperature for cooling shall be reset higher by 5°F under minimum cooling load conditions. This strategy is described in Section 3.7.2.2 of this document. |
|
|
Cooling System |
DX cooling |
|
|
Cooling Efficiency |
Minimum efficiency based on average output capacity of equipment unit(s) |
|
|
Maximum Supply Temp |
20°F above occupied space heating setpoint |
|
|
Heating System |
Electric resistance, electric reheat terminals |
|
|
Heating Efficiency |
NA |
|
|
Reheat Terminal Airflow |
Fans for PIU units are sized for 50% of peak design primary air. Minimum volume setpoint for reheat is highest of 30% of peak design primary airflow rate, minimum outdoor airflow rate or airflow rate required by applicable rating authority. See Section 3.7.5 for details. |
|
|
Economizer |
Integrated economizer with dry-bulb high limit by climate zone. Refer to building descriptor Outside Air Controls and Economizer, Section 3.7.4, for details. |
|
Table 45. System 7 Description
|
System Description |
VAV system with HW boiler, HW reheat and chilled water (CHW) cooling |
|
Supply Fan Power |
See building descriptor Fan Systems, Section 3.7.3 of this document. |
|
Supply Fan Control |
Variable speed controlled by variable speed drives. The part load performance of VAV fans is required to be modeled in accordance with Fan Part Load Curve in Fan Systems. |
|
Minimum Supply Temp |
20°F below occupied space cooling setpoint |
|
Supply Temp Control |
The air temperature for cooling shall be reset higher by 5°F under minimum cooling load conditions. This strategy is described in Section 3.7.2.2 of this document. |
|
Cooling System |
Chiller |
|
Cooling Efficiency |
Minimum efficiency based on the output capacity of specific equipment unit(s) |
|
Chilled Water Pumping System |
The baseline building design pump power shall be 22 W/gpm. Chilled-water systems with a cooling capacity of 300 tons or more shall be modeled as primary/secondary systems with variable-speed drives on the secondary pumping loop and a minimum flow of 25% of the design flow rate. Chilled-water pumps in systems serving less than 300 tons cooling capacity shall be modeled as a primary/ secondary system with secondary pump riding the pump curve. See Section 3.8.5 of this document for details. |
|
Chiller Type and Number |
Electric chillers shall be used in the baseline building design. The baseline building design’s chiller plant shall be modeled with chillers having the number and type as indicated in Standard 90.1-2019, Table G3.1.3.7, as a function of building peak cooling load. |
|
Maximum Supply Temp |
20°F above occupied space heating setpoint |
|
Reheat Terminal Flow |
System 5: Minimum volume setpoint for reheat is highest of 30% of zone peak flow, minimum outdoor airflow rate or airflow rate required by applicable rating authority. See Section 3.7.5 for details. |
|
Heating System |
Hot water boiler (system 8), hot water reheat |
|
Hot Water Pumping System |
The pumping system shall be modeled as primary-only with continuous variable flow and a minimum flow of 25% of the design flow rate. Hot-water systems serving 120,000 ft2 or more shall be modeled with variable-speed drives, and systems serving less than 120,000 ft2 shall be modeled as riding the pump curve. |
|
Heating Efficiency |
Minimum efficiency based on the output capacity of specific baseline equipment unit(s) |
|
Economizer |
Integrated economizer with dry-bulb high limit by climate zone. Refer to building descriptor ‘Outside Air Controls and Economizer’, Section 3.7.4, for details. |
Table 46. System 8 Description
|
System Description |
VAV with CHW cooling, electric resistance heating, and PFP boxes with electric heat |
|
Supply Fan Power |
See building descriptor Fan Systems, Section 3.7.3 of this document |
|
Supply Fan Control |
Variable speed controlled by variable speed drives. The part load performance of VAV fans is required to be modeled in accordance with section Fan Part Load Curve in Fan Systems. |
|
Minimum Supply Temp |
20°F below occupied space cooling setpoint |
|
Supply Temp Control |
The air temperature for cooling shall be reset higher by 5°F under minimum cooling load conditions. This strategy is described in Section 3.7.2.2 of this document. |
|
Cooling System |
Chiller |
|
Cooling Efficiency |
Minimum efficiency based on the proposed output capacity of specific equipment unit(s) |
|
Chilled Water Pumping System |
The baseline building design pump power shall be 22 W/gpm. Chilled-water systems with a cooling capacity of 300 tons or more shall be modeled as primary/secondary systems with variable-speed drives on the secondary pumping loop and a minimum flow of 25% of the design flow rate. Chilled-water pumps in systems serving less than 300 tons cooling capacity shall be modeled as a primary/secondary system with secondary pump riding the pump curve. See Section 3.8.5 of this document for details. |
|
Chiller Type and Number |
Electric chillers shall be used in the baseline building design. The baseline building design’s chiller plant shall be modeled with chillers having the number and type as indicated in Standard 90.1-2019, Table G3.1.3.7, as a function of building peak cooling load. |
|
Maximum Supply Temp |
20°F above occupied space heating setpoint |
|
Heating System |
Electric resistance, electric resistance reheat |
|
Reheat Terminal Airflow |
Fans for PIU units are sized for 50% of peak design primary air. Minimum volume setpoint for reheat is highest of 30% of peak design primary airflow rate, minimum outdoor airflow rate or airflow rate required by applicable rating authority. See Section 3.7.5 for details. |
|
Hot Water Pumping System |
N/A |
|
Heating Efficiency |
N/A |
|
Economizer |
Integrated dry bulb economizer with dry-bulb high limit based on climate zone. Refer to building descriptor Outside Air Controls and Economizer, Section 3.7.4, for details. |
Table 47. System 9 and System 10 Description
|
Heating and ventilation only system |
|
|
Supply Fan Power |
See building descriptor Fan Systems, Section 3.7.3 of this document |
|
Supply Fan Control |
Constant volume |
|
Minimum Supply Temp |
N/A |
|
Cooling System |
None |
|
Cooling Efficiency |
N/A |
|
Maximum Supply Temp |
20°F above occupied space heating setpoint |
|
Heating System |
Gas furnace |
|
Hot Water Pumping System |
N/A |
|
Heating Efficiency |
Minimum efficiency based on the baseline output capacity of specific equipment unit(s) |
|
Economizer |
Not required for system 9 |
|
System 10 Description |
Heating and ventilation only system |
|
Supply Fan Power |
See building descriptor ‘Fan Systems’ |
|
Supply Fan Control |
Constant volume |
|
Minimum Supply Temp: |
N/A |
|
Cooling System |
None |
|
Cooling Efficiency |
N/A |
|
Maximum Supply Temp |
20°F above occupied space heating setpoint |
|
Heating System |
Electric resistance |
|
Hot Water Pumping System |
N/A |
|
Heating Efficiency |
N/A |
|
Economizer |
Not required for system 10 |
Table 48. System 11 Description
|
System 11 Description |
Single zone variable air volume system |
|
Supply Fan Power |
See building descriptor Fan Systems, Section 3.7.3 of this document |
|
Supply Fan Control |
Variable speed controlled by variable speed drives. The part load performance of VAV fans is required to be modeled in accordance with section Fan Part Load Curve in Fan Systems |
|
Minimum Supply Temp |
20°F below occupied space cooling setpoint |
|
Cooling System |
Chiller |
|
Cooling Efficiency |
Minimum efficiency based on the proposed output capacity of specific equipment unit(s) |
|
Chilled Water Pumping System |
The baseline building design pump power shall be 22 W/gpm. Chilled-water systems with a cooling capacity of 300 tons or more shall be modeled as primary/secondary systems with variable-speed drives on the secondary pumping loop and a minimum flow of 25% of the design flow rate. Chilled-water pumps in systems serving less than 300 tons cooling capacity shall be modeled as a primary/secondary system with secondary pump riding the pump curve. See Section 3.8.5 of this document for details. |
|
Chiller Type and Number |
Electric chillers shall be used in the baseline building design. The baseline building design’s chiller plant shall be modeled with chillers having the number and type as indicated in Standard 90.1-2019, Table G3.1.3.7, as a function of building peak cooling load. |
|
Maximum Supply Temp |
20°F above occupied space heating setpoint |
|
Heating System |
For climate zones 0 to 3A, the baseline system shall be modeled with electric resistance heating. For all other climate zones, the heating system shall be hot-water fossil-fuel boiler. |
|
Hot Water Pumping System |
When boilers are required, the pumping system shall be modeled as primary-only with continuous variable flow and a minimum flow of 25% of the design flow rate. Hot-water systems serving 120,000 ft2 or more shall be modeled with variable-speed drives, and systems serving less than 120,000 ft2 shall be modeled as riding the pump curve. |
|
Heating Efficiency |
NA for electric resistance heating. For hot-water boilers, the minimum efficiency based on the output capacity of specific baseline equipment unit(s) |
|
Reheat Terminal Flow |
N/A |
|
Economizer |
Integrated dry bulb economizer with dry-bulb high limit based on climate zone. Refer to building descriptor Outside Air Controls and Economizer, Section 3.7.4, for details. |
Table 49. System 12 and 13 Description
|
System 12, 13 Description |
Single-zone system |
|
Supply Fan Power |
See building descriptor Fan Systems, Section 3.7.3 of this document |
|
Supply Fan Control |
Constant volume |
|
Minimum Supply Temp |
N/A |
|
Cooling System |
Chilled Water |
|
Cooling Efficiency |
Minimum efficiency based on the proposed output capacity of specific equipment unit(s) |
|
Chilled Water Pumping System |
The baseline building design pump power shall be 22 W/gpm. Chilled-water systems with a cooling capacity of 300 tons or more shall be modeled as primary/secondary systems with variable-speed drives on the secondary pumping loop and a minimum flow of 25% of the design flow rate. Chilled-water pumps in systems serving less than 300 tons cooling capacity shall be modeled as a primary/secondary system with secondary pump riding the pump curve. See Section 3.8.5 of this document for details. |
|
Chiller Type and Number |
Electric chillers shall be used in the baseline building design. The baseline building design’s chiller plant shall be modeled with chillers having the number and type as indicated in Standard 90.1-2019, Table G3.1.3.7, as a function of building peak cooling load. |
|
Maximum Supply Temp |
20°F above occupied space heating setpoint |
|
Heating System |
Hot-water fossil fuel boiler for system 12 and electric resistance heating for system 13. |
|
Hot Water Pumping System |
When boilers are required, the pumping system shall be modeled as primary-only with continuous variable flow and a minimum flow of 25% of the design flow rate. Hot-water systems serving 120,000 ft2 or more shall be modeled with variable-speed drives, and systems serving less than 120,000 ft2 shall be modeled as riding the pump curve. |
|
Heating Efficiency |
NA for electric resistance heating. For hot-water boilers, the minimum efficiency based on the output capacity of specific baseline equipment unit(s) |
|
Reheat Terminal Flow |
N/A |
|
Economizer |
Integrated dry bulb economizer with dry-bulb high limit based on climate zone. Refer to building descriptor ‘Outside Air Controls and Economizer’, Section 3.7.4, for details. |
Table 50. Summary of Baseline Building Secondary HVAC System Properties
|
System |
Fan Control |
Economizer |
Cooling Type |
Cooling Efficiency |
Minimum Supply T. |
Heating Type |
Heating Efficiency |
Maximum Supply T. |
|
System 1-PTAC |
Constant volume |
Not required |
Direct Expansion |
Minimum SEER EER, COP or kW/ton based on equipment type and output capacity of proposed unit(s). Adjusted EER is calculated to account for supply fan energy. |
20 °F below occupied space cooling setpoint |
Hot-water fossil fuel boiler |
Minimum AFUE, Thermal Efficiency, COP or HSPF based on equipment type and output capacity of baseline unit(s). |
20 °F above space temperature setpoint for systems 1-4 and 11-13.
Same as maximum reset cooling supply air temperature for systems 5-8 and 105 °F for systems 9 and 10 |
|
System 2-PTHP |
Electric heat pump |
|||||||
|
System 3-PSZ-AC |
Integrated economizer with dry-bulb high limit by climate zone. |
Fossil fuel furnace |
||||||
|
System 4-PSZ-HP |
Electric heat pump |
|||||||
|
System 5-PVAV |
Variable volume |
Hot-water fossil fuel boiler |
||||||
|
System 6-PVAV / PFP |
Electric resistance |
|||||||
|
System 7-VAV |
Chilled water |
Hot-water fossil fuel boiler |
||||||
|
System 8-VAV / PFP |
Electric resistance |
|||||||
|
System 9/10-HV Furnace |
Constant volume |
Not required |
None |
None |
Fossil fuel furnace |
|||
|
HV Electric |
Electric resistance |
|||||||
|
System 11-SZ-VAV |
Variable volume |
Integrated economizer with dry-bulb high limit by climate zone. |
Chilled water |
See 6.8 Primary Systems |
See note. |
|||
|
System 12-SZ-CV-HW |
Constant Volume |
Hot-water fossil fuel boiler |
||||||
|
System 13-SZ-CV-ER |
Electric resistance |
This group of building descriptors relate to the secondary HVAC systems.
This group of building descriptors relate to the secondary HVAC systems.