ASHRAE-90.1-2022- - Page 087
Extracted Content
Table 6.5.1-1 Minimum Fan-Cooling Unit Size for which an Economizer Is Required
| Climate Zone | Cooling Capacity for which an Economizer Is Required | Application |
|---|---|---|
| 0A, 0B, 1A, 1B | No economizer requirement | All |
| 2A, 2B, 3A, 4A, 5A, 6A, 3B, 3C, 4B, 4C, 5B, 5C, 6B, 7, 8 | 33,000 Btu/h | Fan-cooling units located outside the building |
| 2A, 2B, 3A, 4A, 5A, 6A, 3B, 3C, 4B, 4C, 5B, 5C, 6B, 7, 8 | 54,000 Btu/h | All other fan-cooling-unit locations |
Table 6.5.1-2 Eliminate Required Economizer for Comfort Cooling by Increasing Cooling Efficiency
| Climate Zone | Efficiency Improvement a |
|---|---|
| 2A | 17% |
| 2B | 21% |
| 3A | 27% |
| 3B | 32% |
| 3C | 65% |
| 4A | 42% |
| 4B | 49% |
| 4C | 64% |
| 5A | 49% |
| 5B | 59% |
| 5C | 74% |
| 6A | 56% |
| 6B | 65% |
| 7 | 72% |
| 8 | 77% |
a. If a unit is rated with an annualized or part-load metric, then to eliminate the required economizer, only the annualized or part-load minimum cooling
efficiency of the unit must be increased by the percentage shown. If the unit is only rated with a full-load metric like EER cooling then these must be increased by the percentage shown. To determine the efficiency required to eliminate the economizer when the unit equipment efficiency is rated with an energy-input divided by a thermal-output metric, the metric shall first be converted to COP by the efficiency improvement percentage shown. The COP shall then be converted back to the original rated metric to establish the efficiency required to eliminate the economizer. Informative Note: Some examples of annualized or part-load metrics are IPLV .IP, IEER, and SEER .
- Chilled-water cooling systems without a fan or that use induced airflow, where the total capacity of these systems is less than 1,000,000 Btu/h in Climate Zones 0, 1B, and 2 through 4; less than 1,400,000 Btu/h in Climate Zones 5 through 8; or any size in Climate Zone 1A.
- Systems that include nonparticulate air treatment as required by Standard 62.1, Section 6.2.1.
- In hospitals and ambulatory surgery centers, where more than 75% of the air designed to be supplied by the system is to spaces that are required to be humidified above 35°F dew-point temperature to comply with applicable codes or accreditation standards; in all other buildings, where more than 25% of the air designed to be supplied by the system is to spaces that are designed to be humidified above 35°F dew-point temperature to satisfy process application needs. This exception does not apply to computer rooms .
- Systems that include a condenser heat recovery system with a minimum capacity as defined in Section 6.5.6.2.2.
- Systems that serve residential spaces where the system capacity is less than five times the requirement listed in Table 6.5.1-1.
- Systems that serve spaces whose sensible cooling load at design conditions, excluding transmission less than or equal to transmission losses at an outdoor temperature of 60°F.
- Systems expected to operate fewer than 20 hours per week.
ANSI/ASHRAE/IES Standard 90.1-2022 (I-P) 85