UpCodes logo
// CODE SNIPPET

6.5.6 Energy Recovery

2021 Oregon Energy Efficiency Specialty Code (OEESC) > 6 Heating, Ventilating, and Air Conditioning > 6.5 Prescriptive Compliance Path > 6.5.6 Energy Recovery
Go To Full Code Chapter
6.5.6.1 Exhaust Air Energy Recovery
6.5.6.1.1 Nontransient Dwelling Units
Nontransient dwelling units shall be provided with outdoor air energy recovery ventilation systems. For nontransient dwelling units, energy recovery systems shall result in an enthalpy recovery ratio of at least 50% at cooling design condition and at least 60% at heating design condition. The energy recovery system shall provide the required enthalpy recovery ratio at both heating and cooling design conditions, unless one mode is not required for the climate zone by the exceptions below.
Exceptions to 6.5.6.1.1
  1. Nontransient dwelling units in Climate Zone 3C.
  2. Nontransient dwelling units with no more than 500 ft2 of conditioned floor area in Climate Zone 0, 1, 2, 3, 4C, and 5C.
  3. Enthalpy recovery ratio requirements at heating design condition in Climate Zones 0, 1, and 2.
  4. Enthalpy recovery ratio requirements at cooling design condition in Climate Zones 4, 5, 6, 7, 8.
6.5.6.1.2 Spaces Other Than Nontransient Dwelling Units
Each fan system serving spaces other than nontransient dwelling units shall have an energy recovery system where the design supply fan airflow rate exceeds the value listed in Tables 6.5.6.1.2-1 and 6.5.6.1.2-2, based on the climate zone and percentage of outdoor air at design airflow conditions. Table 6.5.6.1.2-1 shall be used for all ventilation systems that operate less than 8000 hours per year, and Table 6.5.6.1.2-1 shall be used for all ventilation systems that operate 8000 or more hours per year.
For spaces other than nontransient dwelling units, energy recovery systems shall result in an enthalpy recovery ratio of at least 50%. The energy recovery system shall provide the required enthalpy recovery ratio at both heating and cooling design conditions, unless one mode is not required for the climate zone by the exceptions below. Provision shall be made to bypass or control the energy recovery system to permit air economizer operation as required by Section 6.5.1.1.
Exceptions to 6.5.6.1.2
  1. Laboratory systems meeting Section 6.5.7.3.
  2. Systems serving spaces that are not cooled and that are heated to less than 60°F.
  3. Heating energy recovery where more than 60% of the outdoor air heating energy is provided from site-recovered energy or site-solar energy in Climate Zones 5 through 8.
  4. Enthalpy recovery ratio requirements at heating design condition in Climate Zones 0, 1, and 2.
  5. Enthalpy recovery ratio requirements at cooling design condition in Climate Zones 3C, 4C, 5B, 5C, 6B, 7, and 8.
  6. Where the sum of the airflow rates exhausted and relieved within 20 ft of each other is less than 75% of the design outdoor airflow rate, excluding exhaust air that is
    1. used for another energy recovery system,
    2. not allowed by ASHRAE/ASHE Standard 170 for use in energy recovery systems with leakage potential, or
    3. of Class 4 as defined in ASHRAE Standard 62.1.
  7. Systems in Climate Zones 0 through 4 requiring dehumidification that employ series energy recovery and have a minimum SERR of 0.40.
  8. Systems expected to operate less than 20 hours per week at the outdoor air percentage covered by Table 6.5.6.1.2-1.
  9. Indoor pool dehumidifiers meeting Section 6.5.6.4.
Table 6.5.6.1.2-1 Exhaust Air Energy Recovery Requirements for Ventilation Systems Operating Less than 8000 Hours per Year
Climate Zone % Outdoor Air at Full Design Airflow Rate
≥10% and <20% ≥20% and <30% ≥30% and < 40% ≥40% and < 50% ≥50% and < 60% ≥60% and <70% ≥70% and < 80% ≥80%
Design Supply Fan Airflow Rate, cfm
3B, 3C, 4B, 4C, 5B NR NR NR NR NR NR NR NR
0B, 1B, 2B,5C NR NR NR NR ≥26000 ≥12000 ≥5000 ≥4000
6B ≥28,000 ≥26,500 ≥11000 ≥5500 ≥4500 ≥3500 ≥ 2500 ≥1500
0A, 1A, 2A, 3A, 4A, 5A, 6A ≥26,000 ≥16,000 ≥5500 ≥4500 ≥3500 ≥2000 ≥1000 >120
7,8 ≥4500 ≥4000 ≥2500 ≥1000 ≥140 ≥120 ≥100 ≥80
NR—Not required
Table 6.5.6.1.2-2 Exhaust Air Energy Recovery Requirements for Ventilation Systems Operating Greater than or Equal to 8000 Hours per Year
Climate Zone % Outdoor Air at Full Design Airflow Rate
≥10% and <20% ≥20% and <30% ≥30% and < 40% ≥40% and < 50% ≥50% and < 60% ≥60% and <70% ≥70% and < 80% ≥80%
Design Supply Fan Airflow Rate, cfm
3C NR NR NR NR NR NR NR NR
0B, 1B, 2B, 3B, 4C, 5C NR ≥19,500 ≥9000 ≥5000 ≥4000 ≥3000 ≥1500 ≥120
0A, 1A, 2A, 3A, 4B, 5B ≥2500 ≥2000 ≥1000 ≥500 ≥140 ≥120 ≥100 ≥80
4A, 5A, 6A, 6B, 7, 8 ≥200 ≥130 ≥100 ≥80 ≥70 ≥60 ≥50 ≥40
NR—Not required
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:
  1. The facility operates 24 hours a day.
  2. The total installed heat-rejection capacity of the water-cooled systems exceeds 6,000,000 Btu/h of heat rejection.
  3. 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
  1. 60% of the peak heat-rejection load at design conditions or
  2. preheat of the peak service hot-water draw to 85°F.
Exceptions to 6.5.6.2.2
  1. 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.
  2. Facilities that provide 60% of their service water heating from site-solar 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 heat-pump 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:
  1. 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.
  2. 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 (1,100 kW) of cooling.
  3. Simultaneous heating, including reheat, and cooling occurs above 60°F (16°C) 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 ft2 in size shall include one of the following:
  1. An exhaust air sensible energy recovery system with a sensible energy recovery ratio of at least 50%
  2. 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
  3. 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.
Upcodes Diagrams

Related Code Sections

6.5.6 Heating, Ventilating, and Air Conditioning, Energy Recovery
Nontransient dwelling units shall be provided with outdoor air energy recovery ventilation systems. For nontransient dwelling units, energy recovery ...
2021 Oregon Energy Efficiency Specialty Code (OEESC) > 6 Heating, Ventilating, and Air Conditioning > 6.5 Prescriptive Compliance Path > 6.5.6 Energy Recovery
6.8 Systems and Equipment, Energy Recovery Systems
Energy recovery systems shall be located upstream of filters required by Section 6.4. If energy recovery systems are used, the systems shall ...
Portland Ventilation of Health Care Facilities 2017 > 6 Systems and Equipment > 6.8 Energy Recovery Systems
Section 514 Exhaust Systems, Energy Recovery Ventilation Systems
Energy recovery ventilation systems shall be installed in accordance with this section. Where required for purposes of energy conservation, energy ...
2019 Oregon Mechanical Specialty Code > 5 Exhaust Systems > 514 Energy Recovery Ventilation Systems
Section 514 Exhaust Systems, Energy Recovery Ventilation Systems
Energy recovery ventilation systems shall be installed in accordance with this section. Where required for purposes of energy conservation, energy ...
2022 Oregon Mechanical Specialty Code > 5 Exhaust Systems > 514 Energy Recovery Ventilation Systems
G3.1.2.10 Normative Appendix G Performance Rating Method, Exhaust Air Energy Recovery
% or greater shall have an energy recovery system with at least 50% enthalpy recovery ratio. Fifty percent enthalpy recovery ratio shall mean a change ...
2021 Oregon Energy Efficiency Specialty Code (OEESC) > Normative Appendix G Performance Rating Method > G3 Calculation of the Proposed Design and Baseline Building Performance > G3.1 Building Performance Calculations > G3.1.2 General Baseline HVAC System Requirements > G3.1.2.10 Exhaust Air Energy Recovery