ASHRAE-90.1-2022- - Page 097
Extracted Content
| Table 6.5.3.7 Minimum Fan Efficacy for Low-Power | Fans | Col3 |
|---|---|---|
| System Type | Minimum Fan Efficacy a, b, cfm/W | Test Method and Rating Conditions |
| HRV c, ERV d, or other system with exhaust air_energy_ recovery | 1.2 | CAN/CSA 439-18 |
| Transfer fans; in-line e supply or exhaust fan | 3.8 | ASHRAE Standard 51 |
| Other exhaust fan, <90 cfm | 2.8 | 2.8 |
| Other exhaust fan,90 cfm and200 cfm | 3.5 | 3.5 |
| Other exhaust fan, >200 cfm | 4.0 | 4.0 |
a. Fan efficacy is the volumetric fan airflow rate divided by total fan motor electrical input power at a specified static pressure difference. b. Fans shall be tested in accordance with the referenced test method. Fan efficacy shall be reported in the product listing or shall be derived from the fan
motor electrical input power and airflow values reported in the product listing or on the label. Fan efficacy for fully ducted HRV or ERV, balanced, and in-line fans shall be determined at a static pressure difference not less than 0.2 in. of water for each airstream. Fan efficacy for other ducted fan systems shall be determined at a static pressure difference not less than 0.1 in. of water. c. A heat recovery ventilator (HRV) is a mechanically powered ventilating device with separate intake and exhaust airstreams and a heat exchanger to trans fer a portion of the sensible energy, heat, from one airstream to the other. d. An energy recovery ventilator (ERV) is a mechanically powered ventilating device with separate intake and exhaust airstreams and a heat exchanger to
transfer a portion of the total energy, heat and moisture, from one airstream to the other. e. An in-line fan is an exhaust or supply fan installed with ductwork on both the fan inlet and outlet.
6.5.3.8 Ventilation Design. The required minimum outdoor air rate is the larger of the minimum outdoor air rate or the minimum exhaust air rate required by Standard 62.1, Standard 62.2, Standard 170, or applicable codes or accreditation standards. Outdoor air ventilation systems shall comply with one of the following:
a. Design minimum system outdoor air provided shall not exceed 135% of the required minimum outdoor
air rate. b. Dampers, ductwork, and controls shall be provided that allow the system to supply no more than the
required minimum outdoor air rate with a single set-point adjustment. c. The system includes exhaust air energy recovery complying with Section 6.5.6.1.
6.5.3.9 Occupied-Standby Zone Controls. Zones serving only rooms that are required to have auto- matic partial OFF or automatic full OFF lighting controls per Section 9.4.1.1, where the ASHRAE Standard 62.1 occupancy category permits ventilation air to be reduced to zero when the space is in occupied-standby mode and when using the Ventilation Rate Procedure, shall meet the following within five minutes of all rooms in that zone entering occupied-standby mode .
a. Active heating set point shall be setback at least 1°F. b. Active cooling set point shall be set up at least 1°F. c. All airflow supplied to the zone shall be shut off whenever the space temperature is between the active
heating and cooling set points .
Exception to 6.5.3.9: Multiple zone systems without automatic zone flow control dampers. Informative Note: ASHRAE Guideline 36 includes detailed sequences of control for occupied standby controls of zone air terminal units.
6.5.3.9.1 Occupied-Standby Control of Multiple-Zone Systems. Multiple-zone systems that are capable of resetting the minimum outdoor air set point and that serve zones with occupied-standby zone controls shall reset the minimum outdoor air set point based on a zone outdoor air requirement of zero for all zones in occupied-standby mode .
Informative Note: ASHRAE Guideline 36 includes sequences for this reset . 6.5.4 Hydronic System Design and Control 6.5.4.1 Boiler Turndown. Boiler systems with design input of at least 1,000,000 Btu/h shall comply with the turndown ratio specified in Table 6.5.4.1.
The system turndown requirement shall be met through the use of multiple single-input boilers, one or more modulating boilers, or a combination of single-input and modulating boilers .
All boilers shall meet the minimum efficiency requirements in Table 6.8.1-6. 6.5.4.2 Hydronic Variable Flow Systems. Chilled- and hot-water distribution systems that include three or more control valves designed to modulate or step open and close as a function of load shall be designed for variable fluid flow and shall be capable of and configured to reduce pump flow rates to no more than the larger of 25% of the design flow rate or the minimum flow required by the heating/cooling equip-
ANSI/ASHRAE/IES Standard 90.1-2022 (I-P) 95