ASHRAE-90.1-2022- - Page 103
Extracted Content
6.5.6.1.2.2 Provision for Air Economizer or Bypass Operation. Provision shall be made for both outdoor air and exhaust air to bypass or control the energy recovery system to enable economizer operation as required by Section 6.5.1.1. The bypass or control shall meet the following criteria:
a. For energy recovery systems where the transfer of energy cannot be stopped, bypass provision shall pre vent the total airflow rate of either outdoor air or exhaust air through the energy recovery exchanger from exceeding 10% of the full design airflow rate. b. The pressure drop of the outdoor air through the energy recovery exchanger shall not exceed 0.4 in. of
water; the pressure drop of the exhaust air through the energy recovery exchanger shall not exceed 0.4 in. of water.
Exception to 6.5.6.1.2.2: Energy recovery systems with 80% or more outdoor air at full design air flow rate and not exceeding 10,000 cfm.
6.5.6.2 Heat Recovery for Service Water Heating 6.5.6.2.1 Condenser heat recovery systems shall be installed for heating or preheating of service hot water provided all of the following are true:
a. The facility operates 24 hours a day. b. The total installed heat-rejection capacity of the water-cooled systems exceeds 6,000,000 Btu/h of heat
rejection. c. The design service water-heating load exceeds 1,000,000 Btu/h.
6.5.6.2.2 The required heat recovery system shall have the capacity to provide the smaller of
a. 60% of the peak heat-rejection load at design conditions or b. preheat of the peak service hot-water draw to 85°F.
Exceptions to 6.5.6.2.2:
- Facilities that employ condenser heat recovery for space heating with a heat recovery design exceeding 30% of the peak water-cooled condenser load at design conditions .
- Facilities that provide 60% of their service water heating from on-site renewable energy or site- recovered energy or from other sources.
6.5.6.3 Heat Recovery for Space Conditioning. Where heating water is used for space heating, a heatpump chiller meeting the requirements of Table 6.8.1-16 for heat recovery that uses the cooling system return water as the heat source shall be installed, provided all of the following are true:
a. The building is an acute inpatient hospital, where the building or portion of a building is used on a 24 hour basis for the inpatient medical, obstetric, or surgical care for patients. b. The total design chilled-water capacity for the acute inpatient hospital, either air cooled or water cooled,
required at cooling design conditions exceeds 3,600,000 Btu/h of cooling. c. Simultaneous heating, including reheat, and cooling occurs above 60°F outdoor air temperature.
The required heat recovery system shall have a cooling capacity that is at least 7% of the total design chilled-water capacity of the acute inpatient hospital at peak design conditions .
Exception to 6.5.6.3: Buildings in Climate Zones 5C, 6B, 7, and 8. 6.5.6.4 Indoor Pool Dehumidifier Energy Recovery. An indoor pool dehumidifier serving a natatorium with a heated indoor pool over 500 ft [2] in size shall include one of the following:
a. An exhaust air sensible energy recovery system with a sensible energy recovery ratio of at least 50% b. A condenser heat recovery system capable of and configured to use 100% of the heat generated through
dehumidification to heat the pool water when there is a pool water heating load c. An exhaust air energy recovery system that results in an enthalpy recovery ratio of at least 50%
Exception to 6.5.6.4: Natatoriums heated by on-site renewable energy or site recovered energy capable
of and configured to provide at least 60% of the annual heating energy required. 6.5.7 Exhaust Systems 6.5.7.1 Transfer Air. Conditioned supply air delivered to any space with mechanical exhaust shall not exceed the greater of
a. the supply flow required to meet the space heating or cooling load; b. the ventilation rate required by the authority having jurisdiction, the facility Environmental Health and
Safety department, or ASHRAE Standard 62.1; or
ANSI/ASHRAE/IES Standard 90.1-2022 (I-P) 101