Strike Section 6.5.1 of ASHRAE 90.1 in its entirety and insert a new Section 6.5.1 Code in its place in the Energy Conservation Code-Commercial Provisions to read as follows:
6.5.1 Economizers. Each cooling system that has a fan shall include either an air or water economizer meeting the requirements of Sections 6.5.1.1 through 6.5.1.5.
a. The minimum size requirements for economizers for comfort cooling and for computer rooms are defined in Table 6.5.1-1.b. Air-cooled packaged units with a capacity of less than 54,000 Btu/h (16 kW) shall have two stages of capacity control, with the first stage controlling the economizer and the second stage controlling mechanical cooling. Units with a capacity equal to or greater than 54,000 Btu/h (16 kW) shall comply with the staging requirements defined in Section 6.5.3.1c. For systems that control to a fixed leaving air temperature (i.e., variable-air-volume [VAV] systems), the system shall be capable of resetting the supply air temperature up at least 5°F (3°C) during economizer operation. Exceptions: Economizers are not required for the following systems:
1. Individual fan-cooling units with a supply capacity less than the minimum listed in Table 6.5.1-1 for comfort cooling applications.2. Systems that include nonparticulate air treatment as required by Section 6.2.1 in Standard 62.1.3. 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 needs. This exception does not apply to computer rooms.4. Systems that include a condenser heat recovery system with a minimum capacity as defined in Section 6.5.6.2.2.5. Systems that serve residential spaces where the system capacity is less than five times the requirement listed in Table 6.5.1-1.6. Systems that serve spaces whose sensible cooling load at design conditions, excluding transmission and infiltration loads, is less than or equal to trans- mission and infiltration losses at an outdoor temperature of 60°F.7. Systems expected to operate less than 20 hours per week.8. Where the use of outdoor air for cooling will affect supermarket open refrigerated casework systems.9. For comfort cooling where the cooling efficiency meets or exceeds the efficiency improvement requirements in Table 6.5.1-3. a. Where the reduced renewable approach defined in Section 13.1.1.2 is used, Exception (9) shall be permitted to eliminate the economizer requirement, provided the requirements in Table 6.5.1-3 are applied to the efficiency requirements required by Section 13.1.1.2. If the standard renewable approach is chosen as defined in Section 13.1.1.1 then the requirements in Table 6.5.1-3 shall be applied to the efficiency requirements in Tables 6.8.1-1 through 6.8.1-11.10. Systems primarily serving computer rooms where: a. The total design cooling load of all computer rooms in the building is less than 3,000,000 Btu/h and the building in which they are located is not served by a centralized chilled water plant;b. The room total design cooling load is less than 600,000 Btu/h and the building in which they are located is served by a centralized chilled water plant; c. The local water authority does not allow cooling towers; ord. Less than 600,000 Btu/h of computer-room cooling equipment capacity is being added to an existing building.11. For water-cooled units with a capacity less than 54,000 Btu/h (16 kW) that are used in systems where heating and cooling loads are transferred within the building (i.e., water-source heat pump systems), the requirement for an air or water economizer can be eliminated if the condenser-water temperature controls are capable of being set to maintain full-load heat rejection capacity down to a 55°F (12°C) condenser-water supply temperature, and the HVAC equipment is capable of operating with a 55°F (12°C) condenser-water supply temperature.12. Variable refrigerant volume with energy recovery or variable refrigerant flow with energy recovery systems. (VRV/VRF).Strike Section 6.5.2.1 of ASHRAE 90.1 in its entirety and insert a new Section 6.5.2.1 in its place in the Energy Conservation Code-Commercial Provisions to read as follows:
6.5.2.1 Zone Controls. Zone thermostatic controls shall prevent:
c. Mixing or simultaneously supplying air that has been previously mechanically heated and air that has been previously cooled, either by mechanical cooling or by economizer systems; andd. Other simultaneous operation of heating and cooling systems to the same zone. Exceptions:
2. Zones with DDC that comply with all of the following: a. The airflow rate in dead band between heating and cooling does not exceed the larger of the following: (i) 20% of the zone design peak supply rate.(ii) The design outdoor airflow rate for the zone.(iii) Any higher rate that can be demonstrated, to the satisfaction of the authority having jurisdiction, to reduce overall system annual energy usage by offsetting reheat/ recool energy losses through a reduction in outdoor air intake. (iv) The airflow rate required to comply with applicable codes or accreditation standards, such as pressure relationships or minimum air change rates. b. The airflow rate that is reheated, recooled, or mixed shall be less than 50% of the zone design peak supply rate.c. The first stage of heating consists of modulating the zone supply air temperature setpoint up to a maximum setpoint while the airflow is maintained at the dead band flow rate.d. The second stage of heating consists of modulating the airflow rate from the dead band flow rate up to the heating maximum flow rate.3. Laboratory exhaust systems that comply with Section 6.5.7.2.4. Zones where at least 75% of the energy for reheating or for providing warm air in mixing systems is provided from a site-recovered (including condenser heat) or site-solar energy source.Strike Section 6.5.3 of ASHRAE 90.1 in its entirety and insert a new Section 6.5.3 in its place in the Energy Conservation Code-Commercial Provisions to read as follows:
6.5.3 Air System Design and Control. Each HVAC system having a total fan system motor nameplate hp exceeding 5 hp shall meet the provisions of Sections 6.5.3.1 through 6.5.3.5. Hotels and motels with more than 50 guest rooms shall comply with Section 6.5.12.
Strike Table 6.5.3.1-1 of ASHRAE 90.1 in its entirety and insert a new Table 6.5.3.1-1 in its place in the Energy Conservation Code-Commercial Provisions to read as follows:
TABLE 6.5.3.1-1 FAN POWER LIMITATIONa
Limit | Constant Volume | Variable Volume |
Option 1: Fan system motor nameplate hp | Allowable nameplate motor hp | hp <= cfm S · 0.00099 | hp < =cfm S · 0.00135 |
Option 2: Fan system bhp | Allowable fan system bhp | bhp <= cfm S · 0.00084 +A | bhp < =cfm S · 0.00117+A |
a. where:
cfmS = maximum design supply airflow rate to conditioned spaces served by the system in cubic feet per minute hp=maximum combined motor nameplate horsepower
hp= maximum combined fanbrake horsepower
A= sum of (PD × cfmD/4131)
where:
PD= each applicable pressure drop adjustment from Table 6.5.3.1-2 in in. wc
cfmD = the design airflow through each applicable device from Table 6.5.3.1-2 in cubic feet per minute
Strike Section 6.5.3.1.3 of ASHRAE 90.1 in its entirety and insert a new Section 6.5.3.1.3 in its place in the Energy Conservation Code-Commercial Provisions to read as follows:
6.5.3.1.3 Fan Efficiency. Fans shall have a fan efficiency grade (FEG) of 67 or higher based on manufacturers' certified data, as defined by AMCA 205. The total efficiency of the fan at the design point of operation shall be within 10 percentage points of the maximum total efficiency of the fan.
Exceptions:
1. Single fans with a motor nameplate kilowatts of 5 hp or less.2. Multiple fans in series or parallel (e.g., fan arrays) that have a combined motor nameplate kilowatts of 5 hp or less and are operated as the functional equivalent of a single fan.3. Fans that are part of equipment listed under Section 6.4.1.1.4. Fans included in equipment bearing a third- party-certified seal for air or energy performance of the equipment package.5. Powered wall/roof ventilators (PRV).6. Fans outside the scope of AMCA 205.7. Fans that are intended to only operate during emergency conditions. 6.5.6 Energy Recovery
Strike Section 6.5.6.1 of ASHRAE 90.1 in its entirety and insert a new Section 6.5.6.1 in its place in the Energy Conservation Code-Commercial Provisions to read as follows:
6.5.6.1 Exhaust Air Energy Recovery. Each fan system shall have an energy recovery system when the system's sup- ply airflow rate exceeds the value listed in Tables 6.5.6.1-1 and 6.5.6.1-2, based on the climate zone and percentage of outdoor airflow rate at design conditions. Table 6.5.6.1-1 shall be used for all ventilation systems that operate less than 8000 hours per year, and Table 6.5.6.1-2 shall be used for all ventilation systems that operate 8000 or more hours per year.
Energy recovery systems required by this section shall have at least 60% energy recovery effectiveness. Sixty percent energy recovery effectiveness shall mean a change in the enthalpy of the outdoor air supply equal to 60% of the difference between the outdoor air and return air enthalpies at design conditions. 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:
1. Laboratory systems meeting Section 6.5.7.2.2. Systems serving spaces that are not cooled and that are heated to less than 60°F.3. Systems exhausting toxic, flammable, paint, or corrosive fumes or dust.4. Commercial kitchen hoods used for collecting and removing grease vapors and smoke.5. Where more than 60% of the outdoor air heating energy is provided from site-recovered or site solar energy.6. Where the largest source of air exhausted at a single location at the building exterior is less than 75% of the design outdoor airflow rate.7. Systems requiring dehumidification that employ energy recovery in series with the cooling coil.8. Systems expected to operate less than 20 hours per week at the outdoor air percentage covered by Table 6.5.6.1-1. Insert a new Section 6.5.6.3 in the Energy Conservation Code-Commercial Provisions to read as follows:
6.5.6.3 Supermarket Heat Recovery. Supermarkets with a floor area of 25,000 ft2 (2500 m2) or greater shall recover waste heat from the condenser heat rejection on permanently installed refrigeration and/or HVAC equipment meeting one of the following criteria:
a. 25% of the refrigeration system full-load total heat rejection.b. 80% of the space heat, service water heating, and dehumidification reheat. If a recovery system is used that is installed in the refrigeration system, the system shall not increase the saturated condensing temperature at design conditions by more than 5°F (3°C) and shall not impair other head pressure control/energy reduction strategies.
6.5.7.1 Kitchen Exhaust Systems
Strike Section 6.5.7.1.3 of ASHRAE 90.1 in its entirety and insert a new Section 6.5.7.1.3 in its place in the Energy Conservation Code-Commercial Provisions to read as follows:
6.5.7.1.3 For kitchen/dining facilities with total kitchen hood exhaust airflow rate greater than 2000 cfm, the maximum exhaust flow rate for each hood shall be determined in accordance with Table 6.5.7.1.3 For single hoods, or hood sections installed over appliances with different duty ratings, the maximum allowable exhaust flow rate for the hood or hood section shall be determined in accordance with Table 6.5.7.1.3 for the highest appliance duty rating under the hood or hood section. Refer to ASHRAE Standard 154 for definitions of hood type, appliance duty, and net exhaust flow rate.
Exception: When at least 75% of all the replacement air is transfer air that would otherwise be exhausted.
Strike Section 6.5.7.1.4 of ASHRAE 90.1 in its entirety and insert new Section 6.5.7.1.4 in its place in the Energy Conservation Code-Commercial Provisions to read as follows:
6.5.7.1.4 Kitchen/dining facilities with total kitchen hood exhaust airflow rate greater than 2000 cfm shall comply with at least one of the following:
a. At least 50% of all replacement air shall be transfer air that would otherwise be exhausted.b. At least 75% of kitchen hood exhaust air shall be controlled by a demand ventilation system(s), which shall: 1. be capable of reducing exhaust and replacement air system airflow rates by no more than the larger of: i. 50% of total design exhaust and replacement air system airflow rate orii. the outdoor airflow and exhaust rates required to meet the ventilation and exhaust requirements of Sections 6.2 and 6.5 of ANSI/ASHRAE Standard 62.1 for the zone.2. include controls to modulate airflow in response to appliance operation and to maintain full capture and containment of smoke, effluent, and combustion products during cooking and idle;3. include controls that result in full flow when the demand ventilation system(s) fail to modulate airflow in response to appliance operation; and4. allow occupants to temporarily override the system(s) to full flow.Insert a new Section 6.5.12 in the Energy Conservation Code-Commercial Provisions to read as follows:
6.5.12 Automatic Control of HVAC in Hotel/Motel Guest Rooms. In hotels and motels with more than 50 guest rooms, automatic controls of HVAC equipment serving each guest room shall be configured according to the following requirements.
6.5.12.1 HVAC Setpoint Control. Within 30 minutes of all occupants leaving the guest room, HVAC setpoints shall be automatically raised by at least 5°F (3°C) from the occupant setpoint in the cooling mode and automatically lowered by at least 5°F (3°C) from the occupant setpoint in the heating mode. When the guest room is unrented and unoccupied, HVAC setpoints shall be automatically reset to 80°F (27°C) or higher in the cooling mode and to 60°F (16°C) or lower in the heating mode. Unrented and unoccupied guest rooms shall be determined by either of the following criteria:
a. The guest room has been continuously unoccupied for up to 16 hours.b. A networked guest-room control system indicates the guest room is unrented and the guest room is unoccupied for no more than 30 minutes. Exception to 6.5.12.1:
1. A networked guest-room control system may return the thermostat setpoints to their default setpoints 60 minutes prior to the time the room is scheduled to be occupied. 2. Cooling for humidity control shall be permitted during unoccupied periods. 6.5.12.2 Ventilation Control. Within 30 minutes of all occupants leaving the guest room, ventilation and exhaust fans shall be automatically turned off, or isolation devices serving each guest room shall automatically shut off the supply of outdoor air to the room and shut off exhaust air from the guest room.
Exception: Central exhaust systems for bathrooms.
D.C. Mun. Regs. tit. 12, 12-I6.5
Final Rulemaking published at 67 DCR 5679 (5/29/2020)