Heads up: There are no amended sections in this chapter.
Mechanical equipment and systems serving the heating, cooling, ventilating, or refrigeration needs of new buildings shall comply with the requirements of this section as described in Section 6.2.
Mechanical equipment and systems serving the heating, cooling, ventilating, or refrigeration needs of additions to existing buildings shall comply with the requirements of this section as described in Section 6.2.

Exception: When HVACR to an addition is provided by existing HVACR systems and equipment, such existing systems and equipment shall not be required to comply with this standard. However, any new systems or equipment installed must comply with specific requirements applicable to those systems and equipment.

New HVACR equipment as a direct replacement of existing HVACR equipment shall comply with the specific minimum efficiency requirements applicable to that equipment.
New cooling systems installed to serve previously uncooled spaces shall comply with this section as described in Section 6.2.
Alterations to existing cooling systems shall not decrease economizer capability unless the system complies with Section 6.5.1.
New and replacement ductwork shall comply with Sections 6.4.4.1 and 6.4.4.2.
New and replacement piping shall comply with Section 6.4.4.1.

Exceptions to 6.1.1.3: Compliance shall not be required

  1. for equipment that is being modified or repaired but not replaced, provided that such modifications and/or repairs will not result in an increase in the annual energy consumption of the equipment using the same energy type;
  2. where a replacement or alteration of equipment requires extensive revisions to other systems, equipment, or elements of a building, and such replaced or altered equipment is a like-for-like replacement;
  3. for a refrigerant change of existing equipment;
  4. for the relocation of existing equipment; or
  5. for ducts and piping where there is insufficient space or access to meet these requirements.
Compliance with Section 6 shall be achieved by meeting all requirements for Sections 6.1, "General"; Section 6.7, "Submittals"; Section 6.8, "Minimum Equipment Efficiency Tables"; and one of the following:
  1. Section 6.3, "Simplified Approach Option for HVAC Systems"
  2. Sections 6.4, "Mandatory Provisions" and 6.5, "Prescriptive Path"
  3. Sections 6.4, "Mandatory Provisions" and 6.6, "Alternative Compliance Path"
Projects using the Energy Cost Budget Method (see Section 11 of this standard) must comply with Section 6.4, the mandatory provisions of this section, as a portion of that compliance path.
The simplified approach is an optional path for compliance when the following conditions are met:
  1. The building is two stories or fewer in height.
  2. Gross floor area is less than 25,000 ft2.
  3. Each HVAC system in the building complies with the requirements listed in Section 6.3.2.
The HVAC system must meet all of the following criteria:
  1. The system serves a single HVAC zone.
  2. The equipment must meet the variable flow requirements of Section 6.5.3.2.1.
  3. Cooling (if any) shall be provided by a unitary packaged or split-system air conditioner that is either air cooled or evaporatively cooled, with efficiency meeting the requirements shown in Table 6.8.1-1 (air conditioners), Table 6.8.1-2 (heat pumps), or Table 6.8.1-4 (packaged terminal and room air conditioners and heat pumps) for the applicable equipment category.
  4. The system shall have an air economizer meeting the requirements of Section 6.5.1.
  5. Heating (if any) shall be provided by a unitary packaged or split-system heat pump that meets the applicable efficiency requirements shown in Table 6.8.1-2 (heat pumps) or Table 6.8.1-4 (packaged terminal and room air conditioners and heat pumps), a fuel-fired furnace that meets the applicable efficiency requirements shown in Table 6.8.1-5 (furnaces, duct furnaces, and unit heaters), an electric resistance heater, or a baseboard system connected to a boiler that meets the applicable efficiency requirements shown in Table 6.8.1-6 (boilers).
  6. The system shall meet the exhaust air energy recovery requirements of Section 6.5.6.1.
  7. The system shall be controlled by a manual changeover or dual setpoint thermostat.
  8. If a heat pump equipped with auxiliary internal electric resistance heaters is installed, controls shall be provided that prevent supplemental heater operation when the heating load can be met by the heat pump alone during both steady-state operation and setback recovery. Supplemental heater operation is permitted during outdoor coil defrost cycles. The heat pump must be controlled by either (1) a digital or electronic thermostat designed for heat-pump use that energizes auxiliary heat only when the heat pump has insufficient capacity to maintain setpoint or to warm up the space at a sufficient rate or (2) a multistage space thermostat and an outdoor air thermostat wired to energize auxiliary heat only on the last stage of the space thermostat and when outdoor air temperature is less than 40°F.

    Exception: Heat pumps that comply with the following:

    1. Have a minimum efficiency regulated by NAECA
    2. Meet the requirements in Table 6.8.1-2
    3. Include all usage of internal electric resistance heating
  9. The system controls shall not permit reheat or any other form of simultaneous heating and cooling for humidity control.
  10. Systems serving spaces other than hotel/motel guest rooms, and other than those requiring continuous operation, which have both a cooling or heating capacity greater than 15,000 Btu/h and a supply fan motor power greater than 0.75 hp, shall be provided with a time clock that (1) can start and stop the system under different schedules for seven different day types per week, (2) is capable of retaining programming and time setting during a loss of power for a period of at least ten hours, (3) includes an accessible manual override that allows temporary operation of the system for up to two hours, (4) is capable of temperature setback down to 55°F during off hours, and (5) is capable of temperature setup to 90°F during off hours.
  11. Except for piping within manufacturers' units, HVAC piping shall be insulated in accordance with Tables 6.8.3-1 and 6.8.3-2. Insulation exposed to weather shall be suitable for outdoor service, e.g., protected by aluminum, sheet metal, painted canvas, or plastic cover. Cellular foam insulation shall be protected as above or painted with a coating that is water retardant and provides shielding from solar radiation.
  12. Ductwork and plenums shall be insulated in accordance with Tables 6.8.2-1 and 6.8.2-2 and shall be sealed in accordance with Section 6.4.4.2.1.
  13. Construction documents shall require a ducted system to be air balanced in accordance with industry accepted procedures.
  14. Outdoor air intake and exhaust systems shall meet the requirements of Section 6.4.3.4.
  15. Where separate heating and cooling equipment serves the same temperature zone, thermostats shall be interlocked to prevent simultaneous heating and cooling.
  16. Systems with a design supply air capacity greater than 10,000 cfm shall have optimum start controls.
  17. The system shall comply with the demand control ventilation requirements in Section 6.4.3.8.
  18. The system complies with the door switch requirements in Section 6.5.10.
Equipment shown in Tables 6.8.1-1 through 6.8.1-13 shall have a minimum performance at the specified rating conditions when tested in accordance with the specified test procedure. Where multiple rating conditions or performance requirements are provided, the equipment shall satisfy all stated requirements unless otherwise exempted by footnotes in the table. Equipment covered under the Federal Energy Policy Act of 1992 (EPACT) shall have no minimum efficiency requirements for operation at minimum capacity or other than standard rating conditions. Equipment used to provide water heating functions as part of a combination system shall satisfy all stated requirements for the appropriate space heating or cooling category.

Tables are as follows:

  1. Table 6.8.1-1—Electrically Operated Unitary Air Conditioners and Condensing Units—Minimum Efficiency Requirements
  2. Table 6.8.1-2—Electrically Operated Unitary and Applied Heat Pumps—Minimum Efficiency Requirements
  3. Table 6.8.1-3—Water-Chilling Packages—Efficiency Requirements (see Section 6.4.1.2 for water-cooled centrifugal water-chilling packages that are designed to operate at nonstandard conditions.)
  4. Table 6.8.1-4—Electrically Operated Packaged Terminal Air Conditioners, Packaged Terminal Heat Pumps, Single-Package Vertical Air Conditioners, Single-Package Vertical Heat Pumps, Room Air Conditioners, and Room Air Conditioner Heat Pumps—Minimum Efficiency Requirements
  5. Table 6.8.1-5—Warm-Air Furnaces, Warm-Air Furnaces/ Air-Conditioning Units, Warm-Air Duct Furnaces, and Unit Heaters
  6. Table 6.8.1-6—Gas- and Oil-Fired Boilers—Minimum Efficiency Requirements
  7. Table 6.8.1-7—Performance Requirements for Heat Rejection Equipment
  8. Table 6.8.1-8—Heat Transfer Equipment
  9. Table 6.8.1-9—Electrically Operated Variable-Refrigerant-Flow Air Conditioners—Minimum Efficiency Requirements
  10. Table 6.8.1-10—Electrically Operated Variable-Refrigerant-Flow Air-to-Air and Applied Heat Pumps—Minimum Efficiency Requirements
  11. Table 6.8.1-11—Air Conditioners and Condensing Units Serving Computer Rooms
  12. Table 6.8.1-12—Commercial Refrigerators and Freezers
  13. Table 6.8.1-13—Commercial Refrigeration

All furnaces with input ratings of ≥225,000 Btu/h, including electric furnaces, that are not located within the conditioned space shall have jacket losses not exceeding 0.75% of the input rating. Air conditioners primarily serving computer rooms and covered by ASHRAE Standard 127 shall meet the requirements in Table 6.8.1-11. All other air conditioners shall meet the requirements in Table 6.8.1-1.

Equipment not designed for operation at AHRI Standard 550/590 test conditions of 44°F leaving chilled-fluid temperature and 2.4 gpm/ton evaporator fluid flow and 85°F entering condenser-fluid temperature with 3.0 gpm/ton condenser-fluid flow shall have maximum full-load kW/ton (FL) and part-load rating requirements adjusted using the following equations:

FLadj = FL/Kadj

PLVadj = IPLV/Kadj

Kadj = A × B

where

FL = full-load kW/ton value from Table 6.8.1-3
FLadj = maximum full-load kW/ton rating, adjusted for nonstandard conditions
IPLV = IPLV value from Table 6.8.1-3
PLVadj = maximum NPLV rating, adjusted for nonstandard conditions
A = 0.00000014592 × (LIFT)4 — 0.0000346496 × (LIFT)3 + 0.00314196 × (LIFT)2 — 0.147199 × (LIFT) + 3.9302
B = 0.0015 × LvgEvap + 0.934
LIFT = LvgCond — LvgEvap
LvgCond = full-load condenser leaving fluid temperature (°F)
LvgEvap = full-load evaporator leaving temperature (°F)

The FLadj and PLVadj values are only applicable for centrifugal chillers meeting all of the following full-load design ranges:

•  Minimum Evaporator Leaving Temperature: 36°F

•  Maximum Condenser Leaving Temperature:115°F

•  20°F ≤ LIFT ≤ 80°F

Manufacturers shall calculate the FLadj and PLVadj before determining whether to label the chiller per Section 6.4.1.5. Compliance with 90.1-2007, 2010, 2013, or combinations thereof, shall be labeled on chillers within the scope of the standard.

Centrifugal chillers designed to operate outside of these ranges are not covered by this standard.

Example: Path A 600 ton centrifugal chiller Table 6.8.1-3 efficiencies effective 1/1/2015:

FL = 0.560 kW/ton
IPLV = 0.500 kW/ton
LvgCond = 91.16°F
LvgEvap = 42.00°F
LIFT = 91.16 — 42 = 49.16°F
Kadj = A × B
A = 0.00000014592 × (49.16)4 — 0.0000346496 × (49.16)3 + 0.00314196 x (49.16)2 — 0.147199 × (49.16) + 3.9302 = 1.0228
B = 0.0015 × 42 + 0.934 = 0.9970
FLadj = 0.560/(1.0228 × 0.9970) = 0.549 kW/ton
PLVadj = 0.500/(1.0228 × 0.9970) = 0.490 kW/ton
Equipment with an evaporator leaving fluid temperature higher than 32°F and water-cooled positive displacement chilling packages with a condenser leaving fluid temperature below 115°F shall show compliance with Table 6.8.1-3 when tested or certified with water at standard rating conditions, per the referenced test procedure.
Equipment not listed in the tables referenced in Sections 6.4.1.1 and 6.4.1.2 may be used.
Equipment efficiency information supplied by manufacturers shall be verified by one of the following:
  1. Equipment covered under EPACT shall comply with U.S. Department of Energy certification requirements.
  2. If a certification program exists for a covered product, and it includes provisions for verification and challenge of equipment efficiency ratings, then the product shall be listed in the certification program.
  3. If a certification program exists for a covered product, and it includes provisions for verification and challenge of equipment efficiency ratings, but the product is not listed in the existing certification program, the ratings shall be verified by an independent laboratory test report.
  4. If no certification program exists for a covered product, the equipment efficiency ratings shall be supported by data furnished by the manufacturer.
  5. Where components such as indoor or outdoor coils from different manufacturers are used, the system designer shall specify component efficiencies whose combined efficiency meets the minimum equipment efficiency requirements in Section 6.4.1.
  6. Requirements for plate-type liquid-to-liquid heat exchangers are listed in Table 6.8.1-8.
Mechanical equipment that is not covered by the U.S. National Appliance Energy Conservation Act (NAECA) of 1987 shall carry a permanent label installed by the manufacturer stating that the equipment complies with the requirements of Standard 90.1.
Nonstandard-size packaged terminal air conditioners and heat pumps with existing sleeves having an external wall opening of less than 16 in. high or less than 42 in. wide and having a cross-sectional area less than 670 in.2 shall be factory labeled as follows: Manufactured for nonstandard-size applications only: Not to be installed in new construction projects.
Heating and cooling system design loads for the purpose of sizing systems and equipment shall be determined in accordance with ANSI/ASHRAE/ ACCA Standard 183.
Pump differential pressure (head) for the purpose of sizing pumps shall be determined in accordance with generally accepted engineering standards and handbooks acceptable to the adopting authority. The pressure drop through each device and pipe segment in the critical circuit at design conditions shall be calculated.
The supply of heating and cooling energy to each zone shall be individually controlled by thermostatic controls responding to temperature within the zone. For the purposes of this section, a dwelling unit shall be permitted to be considered a single zone.

Exceptions: Independent perimeter systems that are designed to offset only building envelope loads shall be permitted to serve one or more zones also served by an interior system, provided that

  1. the perimeter system includes at least one thermostatic control zone for each building exposure having exterior walls facing only one orientation for 50 contiguous feet or more and
  2. the perimeter system heating and cooling supply is controlled by a thermostatic control(s) located within the zones(s) served by the system.

Exterior walls are considered to have different orientations if the directions they face differ by more than 45 degrees.

Where used to control both heating and cooling, zone thermostatic controls shall be capable of providing a temperature range or dead band of at least 5°F within which the supply of heating and cooling energy to the zone is shut off or reduced to a minimum.

Exceptions:

  1. Thermostats that require manual changeover between heating and cooling modes
  2. Special occupancy or special applications where wide temperature ranges are not acceptable (such as retirement homes, process applications, museums, some areas of hospitals) and are approved by the authority having jurisdiction
Where heating and cooling to a zone are controlled by separate zone thermostatic controls located within the zone, means (such as limit switches; mechanical stops; or, for DDC systems, software programming) shall be provided to prevent the heating setpoint from exceeding the cooling setpoint minus any applicable proportional band.
HVAC systems shall have the off-hour controls required by Sections 6.4.3.3.1 through 6.4.3.3.4.

Exceptions:

  1. HVAC systems intended to operate continuously
  2. HVAC systems having a design heating capacity and cooling capacity less than 15,000 Btu/h that are equipped with readily accessible manual on/ off controls
HVAC systems shall be equipped with at least one of the following:
  1. Controls that can start and stop the system under different time schedules for seven different day types per week, are capable of retaining programming and time setting during loss of power for a period of at least ten hours, and include an accessible manual override, or equivalent function, that allows temporary operation of the system for up to two hours
  2. An occupant sensor that is capable of shutting the system off when no occupant is sensed for a period of up to 30 minutes
  3. A manually operated timer capable of being adjusted to operate the system for up to two hours
  4. An interlock to a security system that shuts the system off when the security system is activated

Exception: Residential occupancies may use controls that can start and stop the system under two different time schedules per week.

Heating systems shall be equipped with controls configured to automatically restart and temporarily operate the system as required to maintain zone temperatures above an adjustable heating setpoint at least 10°F below the occupied heating setpoint. Cooling systems shall be equipped with controls configured to automatically restart and temporarily operate the mechanical cooling system as required to maintain zone temperatures below an adjustable cooling setpoint at least 5°F above the occupied cooling setpoint or to prevent high space humidity levels.

Exception: Radiant heating systems configured with a setback heating setpoint at least 4°F below the occupied heating setpoint

Individual heating and cooling systems with setback controls and DDC shall have optimum start controls. The control algorithm shall, as a minimum, be a function of the difference between space temperature and occupied setpoint, the outdoor temperature, and the amount of time prior to scheduled occupancy. Mass radiant floor slab systems shall incorporate floor temperature into the optimum start algorithm.
HVAC systems serving zones that are intended to operate or be occupied nonsimultaneously shall be divided into isolation areas. Zones may be grouped into a single isolation area provided it does not exceed 25,000 ft2 of conditioned floor area nor include more than one floor. Each isolation area shall be equipped with isolation devices capable of automatically shutting off the supply of conditioned air and outdoor air to and exhaust air from the area. Each isolation area shall be controlled independently by a device meeting the requirements of Section 6.4.3.3.1. For central systems and plants, controls and devices shall be provided to allow stable system and equipment operation for any length of time while serving only the smallest isolation area served by the system or plant.

Exceptions: Isolation devices and controls are not required for

  1. exhaust air and outdoor air connections to isolation zones when the fan system to which they connect is 5000 cfm and smaller;
  2. exhaust airflow from a single isolation zone of less than 10% of the design airflow of the exhaust system to which it connects; or
  3. zones intended to operate continuously or intended to be inoperative only when all other zones are inoperative.
Stair and elevator shaft vents shall be equipped with motorized dampers that are capable of being automatically closed during normal building operation and are interlocked to open as required by fire and smoke detection systems.
All outdoor air intake and exhaust systems shall be equipped with motorized dampers that will automatically shut when the systems or spaces served are not in use. Ventilation outdoor air and exhaust/relief dampers shall be capable of automatically shutting off during preoccupancy building warm-up, cooldown, and setback, except when ventilation reduces energy costs or when ventilation must be supplied to meet code requirements.

Exceptions:

  1. Back draft gravity (nonmotorized) dampers are acceptable for exhaust and relief in buildings less than three stories in height and for ventilation air intakes and exhaust and relief dampers in buildings of any height located in Climate Zones 1, 2, and 3. Back draft dampers for ventilation air intakes must be protected from direct exposure to wind.
  2. Back draft gravity (nonmotorized) dampers are acceptable in systems with a design outdoor air intake or exhaust capacity of 300 cfm or less.
  3. Dampers are not required in ventilation or exhaust systems serving unconditioned spaces.
  4. Dampers are not required in exhaust systems serving Type 1 kitchen exhaust hoods.
Where outdoor air supply and exhaust/relief dampers are required by Section 6.4.3.4.1, they shall have a maximum leakage rate as indicated in Table 6.4.3.4.3 when tested in accordance with AMCA Standard 500.

TABLE 6.4.3.4.3 Maximum Damper Leakage, cfm per ft2 at 1.0 in. wc

Climate Zone Ventilation Air Intake Exhaust/Relief
Nonmotorizeda Motorized Nonmotorizeda Motorized
1, 2
Any height 20 4 20 4
3
Any height 20 10 20 10
4, 5b, 5c
Fewer than three stories NA 10 20 10
Three or more stories NA 10 NA 10
5a, 6, 7, 8
Fewer than three stories NA 4 20 4
Three or more stories NA 4 NA 4

a. Dampers smaller than 24 in. in either dimension may have leakage of 40 cfm/ft2.

NA = Not allowed

Fans with motors greater than 0.75 hp shall have automatic controls complying with Section 6.4.3.3.1 that are capable of shutting off fans when not required.

Exception: HVAC systems intended to operate continuously.

Enclosed parking garage ventilation systems shall automatically detect contaminant levels and stage fans or modulate fan airflow rates to 50% or less of design capacity, provided acceptable contaminant levels are maintained.

Exceptions:

  1. Garages less than 30,000 ft2 with ventilation systems that do not utilize mechanical cooling or mechanical heating
  2. Garages that have a garage area to ventilation system motor nameplate hp ratio that exceeds 1500 ft2/hp and do not utilize mechanical cooling or mechanical heating.
  3. Where not permitted by the authority having jurisdiction.
Heat pumps equipped with internal electric resistance heaters shall have controls that prevent supplemental heater operation when the heating load can be met by the heat pump alone during both steady-state operation and setback recovery. Supplemental heater operation is permitted during outdoor coil defrost cycles.

Exception: Heat pumps whose minimum efficiency is regulated by NAECA and whose ratings meet the requirements shown in Table 6.8.1-2 and include all usage of internal electric resistance heating.

Humidity control shall prevent the use of fossil fuel or electricity to produce RH above 30% in the warmest zone served by the humidification system and to reduce RH below 60% in the coldest zone served by the dehumidification system. Where a zone is served by a system or systems with both humidification and dehumidification capability, means (such as limit switches, mechanical stops, or, for DDC systems, software programming) shall be provided capable of preventing simultaneous operation of humidification and dehumidification equipment.

Exceptions:

  1. Zones served by desiccant systems, used with direct evaporative cooling in series
  2. Systems serving zones where specific humidity levels are required, such as museums and hospitals, and approved by the authority having jurisdiction or required by accreditation standards and humidity controls are configured to maintain a deadband of at least 10% RH where no active humidification or dehumidification takes place
  3. Systems serving zones where humidity levels are required to be maintained with precision of not more than ±5% RH to comply with applicable codes or accreditation standards or as approved by the authority having jurisdiction
Freeze protection systems, such as heat tracing of outdoor piping and heat exchangers, including self-regulating heat tracing, shall include automatic controls capable of shutting off the systems when outdoor air temperatures are above 40°F or when the conditions of the protected fluid will prevent freezing. Snow- and ice-melting systems shall include automatic controls capable of shutting off the systems when the pavement temperature is above 50°F and no precipitation is falling, and an automatic or manual control that will allow shutoff when the outdoor temperature is above 40°F so that the potential for snow or ice accumulation is negligible.
Demand control ventilation (DCV) is required for spaces larger than 500 ft2 and with a design occupancy for ventilation of ≥25 people per 1000 ft2 of floor area and served by systems with one or more of the following:
  1. Air-side economizer
  2. Automatic modulating control of outdoor air damper
  3. Design outdoor airflow greater than 3000 cfm.

Exceptions:

  1. Systems with the exhaust air energy recovery complying with Section 6.5.6.1
  2. Multiple-zone systems without DDC of individual zones communicating with a central control panel
  3. Systems with a design outdoor airflow less than 750 cfm
  4. Spaces where >75% of the space design outdoor airflow is required for makeup air that is exhausted from the space or transfer air that is required for makeup air that is exhausted from other space(s)
  5. Spaces with one of the following occupancy categories as defined in ASHRAE Standard 62.1: correctional cells, daycare sickrooms, science labs, barbers, beauty and nail salons, and bowling alley seating.
Heating for vestibules, in accordance with Section 5.4.3.4, and air curtains shall include automatic controls configured to shut off the heating system when outdoor air temperatures are above 45°F. Vestibule heating systems shall also be controlled by a thermostat in the vestibule with a setpoint limited to a maximum of 60°F.

Exception: Vestibules with no heating system or that are tempered with transfer air that would otherwise be exhausted.

DDC shall be provided in the applications and qualifications listed in Table 6.4.3.10.1.

TABLE 6.4.3.10.1 DDC Applications and Qualifications

Building Status Application Qualifications
New building Air-handling system and all zones served by the system Individual systems supplying more than three zones and with fan system bhp of 10 hp and larger
New building Chilled-water plant and all coils and terminal units served by the system Individual plants supplying more than three zones and with design cooling capacity of 300,000 Btu/h and larger
New building Hot-water plant and all coils and terminal units served by the system Individual plants supplying more than three zones and with design heating capacity of 300,000 Btu/h and larger
Alteration or addition Zone terminal unit such as VAV box Where existing zones served by the same air-handling, chilled-water, or hot-water system have DDC
Alteration or addition Air-handling system or fan coil Where existing air-handling system(s) and fan-coil(s) served by the same chilled- or hot-water plant have DDC
Alteration or addition New air-handling system and all new zones served by the system Individual systems with fan system bhp of 10 hp and larger and supplying more than three zones and more than 75% of zones are new
Alteration or addition New or upgraded chilled-water plant Where all chillers are new and plant design cooling capacity is 300,000 Btu/h and larger
Alteration or addition New or upgraded hot-water plant Where all boilers are new and plant design heating capacity is 300,000 Btu/h and larger

Exception: DDC is not required for systems using the simplified approach to compliance in accordance with Section 6.3.

Where DDC is required by Section 6.4.3.10.1, the DDC system shall be capable of all of the following, as required, to provide the control logic required in Section 6.5:
  1. Monitoring zone and system demand for fan pressure, pump pressure, heating, and cooling
  2. Transferring zone and system demand information from zones to air distribution system controllers and from air distribution systems to heating and cooling plant controllers
  3. Automatically detecting those zones and systems that may be excessively driving the reset logic and generate an alarm or other indication to the system operator
  4. Readily allowing operator removal of zone(s) from the reset algorithm
Where DDC is required by Section 6.4.3.10.1 for new buildings, the DDC system shall be capable of trending and graphically displaying input and output points.
Insulation required by this section shall be installed in accordance with industry-accepted standards (see Informative Appendix E). These requirements do not apply to HVAC equipment. Insulation shall be protected from damage, including that due to sunlight, moisture, equipment maintenance and wind, but not limited to the following:
  1. Insulation exposed to weather shall be suitable for outdoor service, e.g., protected by aluminum, sheet metal, painted canvas, or plastic cover. Cellular foam insulation shall be protected as above or painted with a coating that is water retardant and provides shielding from solar radiation that can cause degradation of the material.
  2. Insulation covering chilled-water piping, refrigerant suction piping, or cooling ducts located outside the conditioned space shall include a vapor retardant located outside the insulation (unless the insulation is inherently vapor retardant), all penetrations and joints of which shall be sealed.
All supply and return ducts and plenums installed as part of an HVAC air distribution system shall be thermally insulated in accordance with Tables 6.8.2-1 and 6.8.2-2.

Exceptions:

  1. Factory-installed plenums, casings, or ductwork furnished as a part of HVAC equipment tested and rated in accordance with Section 6.4.1.
  2. Ducts or plenums located in heated spaces, semiheated spaces, or cooled spaces.
  3. For runouts less than 10 ft in length to air terminals or air outlets, the rated R-value of insulation need not exceed R-3.5.
  4. Backs of air outlets and outlet plenums exposed to unconditioned or indirectly conditioned spaces with face areas exceeding 5 ft2 need not exceed R-2; those 5 ft2 or smaller need not be insulated.
Piping shall be thermally insulated in accordance with Tables 6.8.3-1 and 6.8.3-2.

Exceptions:

  1. Factory-installed piping within HVAC equipment tested and rated in accordance with Section 6.4.1.
  2. Piping that conveys fluids having a design operating temperature range between 60°F and 105°F, inclusive.
  3. Piping that conveys fluids that have not been heated or cooled through the use of fossil fuels or electricity (such as roof and condensate drains, domestic cold-water supply, natural-gas piping).
  4. Where heat gain or heat loss will not increase energy usage (such as liquid refrigerant piping)
  5. In piping 1 in. or less, insulation is not required for strainers, control valves, and balancing valves.
All thermally ineffective panel surfaces of sensible heating panels, including U-bends and headers, shall be insulated with a minimum of R-3.5. Adjacent envelope insulation counts toward this requirement.
The bottom surfaces of floor structures incorporating radiant heating shall be insulated with a minimum of R-3.5. Adjacent envelope insulation counts toward this requirement.

Exception: Requirements for heated slab-on-grade floors incorporating radiant heating are in Chapter 5.

Ductwork and all plenums with pressure class ratings shall be constructed to Seal Class A, as required to meet the requirements of Section 6.4.4.2.2, and with standard industry practice (see Informative Appendix E). Openings for rotating shafts shall be sealed with bushings or other devices that seal off air leakage. Pressure-sensitive tape shall not be used as the primary sealant unless it has been certified to comply with UL-181A or UL-181B by an independent testing laboratory and the tape is used in accordance with that certification. All connections shall be sealed, including but not limited to spin-ins, taps, other branch connections, access doors, access panels, and duct connections to equipment. Sealing that would void product listings is not required. Spiral lock seams need not be sealed. All duct pressure class ratings shall be designated in the design documents.
Ductwork that is designed to operate at static pressures in excess of 3 in. wc and all ductwork located outdoors shall be leak-tested according to industry-accepted test procedures (see Informative Appendix E). Representative sections totaling no less than 25% of the total installed duct area for the designated pressure class shall be tested. All sections shall be selected by the building owner or the designated representative of the building owner. Positive pressure leakage testing is acceptable for negative pressure ductwork.The maximum permitted duct leakage shall be

Lmax = CLP0.65

where

Lmax = maximum permitted leakage, cfm per 100 ft2 of duct surface area
CL = 4, duct leakage class, cfm per 100 ft2 of duct surface area per 1 in. of water0.65
P = test pressure, which shall be equal to the design duct pressure class rating, in. of water
Site-assembled or site-constructed walk-in coolers and freezers shall conform to the following requirements:
  1. Shall be equipped with automatic door closers that firmly close walk-in doors that have been closed to within 1 in. of full closure.

    Exception: Doors wider than 3 ft 9 in. or taller than 7 ft

  2. Doorways shall have strip doors (curtains), spring-hinged doors, or other method of minimizing infiltration when doors are open.
  3. Walk-in coolers shall contain wall, ceiling, and door insulation of at least R-25 and walk-in freezers at least R-32.

    Exception: Glazed portions of doors or structural members

  4. Walk-in freezers shall contain floor insulation of at least R-28.
  5. Evaporator fan motors that are less than 1 hp and less than 460 V shall use electronically commutated motors (brushless direct-current motors) or three-phase motors.
  6. Lights shall use light sources with an efficacy of 40 lm/W or more, including ballast losses (if any). Light sources with an efficacy of less than 40 lm/W, including ballast losses (if any), may be used in conjunction with a timer or device that turns off the lights within 15 minutes of when the walk-in cooler or walk-in freezer is not occupied by people.
  7. Transparent reach-in doors for walk-in freezers, and windows in walk-in freezer doors, shall be of triple-pane glass, either filled with inert gas or with heat-reflective treated glass.
  8. Transparent reach-in doors for walk-in coolers, and windows in walk-in cooler doors, shall be double-pane glass with heat-reflective treated glass and gas filled, or they shall be triple-pane glass, either filled with inert gas or with heat-reflective treated glass.
  9. Antisweat heaters without antisweat heater controls shall have a total door rail, glass, and frame heater power draw of ≤7.1 W/ft2 of door opening for walk-in freezers and 3.0 W/ft2 of door opening for walk-in coolers.
  10. Antisweat heater controls shall reduce the energy use of the antisweat heater as a function of the relative humidity in the air outside the door or to the condensation on the inner glass pane.
  11. Condenser fan motors that are less than 1 hp shall use electronically commutated motors, permanent split capacitor-type motors, or three-phase motors.
  12. All walk-in freezers shall incorporate temperature-based defrost termination control with a time limit default. The defrost cycle shall terminate first on an upper temperature limit breach and second upon a time limit breach.

Exception: Walk-in coolers and walk-in freezers combined in a single enclosure greater than 3000 ft2

  1. All refrigerated display cases shall conform to Section 6.4.1.1 and Tables 6.8.1-1 through 6.8.1-13.
  2. Lighting in refrigerated display cases and glass doors installed on walk-in coolers and freezers shall be controlled by one of the following:
    1. Automatic time-switch controls to turn off lights during nonbusiness hours. Timed overrides for display cases or walk-in coolers and freezers may be used to turn the lights on for up to one hour and shall automatically time out to turn the lights off.
    2. Motion sensor controls on each display case or walk-in door section that reduce lighting power by at least 50% within three minutes after the area within the sensor range is vacated.
  3. All low-temperature display cases shall incorporate temperature-based defrost termination control with a timelimit default. The defrost cycle shall terminate first on an upper temperature limit breach and second upon a time limit breach.
  4. Antisweat heater controls shall reduce the energy use of the antisweat heater as a function of the relative humidity in the air outside the door or to the condensation on the inner glass pane.
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.

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 and Table 6.5.1-2 for computer room 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 transmission 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.
  10. Systems primarily serving computer rooms where
    1. 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;
    2. 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;
    3. the local water authority does not allow cooling towers; or
    4. less than 600,000 Btu/h of computer-room cooling equipment capacity is being added to an existing building.
  11. Dedicated systems for computer rooms where a minimum of 75% of the design load serves
    1. those spaces classified as an essential facility,
    2. those spaces having a design of Tier IV as defined by ANSI/TIA-942,
    3. those spaces classified under NFPA 70 Article 708—Critical Operations Power Systems (COPS), or
    4. those spaces where core clearing and settlement services are performed such that their failure to settle pending financial transactions could present systemic risk as described in "The Interagency Paper on Sound Practices to Strengthen the Resilience of the U.S. Financial System, April 7, 2003"

TABLE 6.5.1-1 Minimum Fan-Cooling Unit Size for which an Economizer is Required for Comfort Cooling

Climate Zones Cooling Capacity for Which an Economizer is Required
1a, 1b No economizer requirement
2a, 2b, 3a, 4a, 5a, 6a 3b, 3c, 4b, 4c, 5b, 5c, 6b, 7, 8 ≥ 54,000 Btu/h

TABLE 6.5.1-2 Minimum Fan-Cooling Unit Size for which an Economizer is Required for Computer Rooms

Climate Zones Cooling Capacity for Which an Economizer is Required
1a, 1b, 2a, 3a, 4a No economizer requirement
2b, 5a, 6a, 7, 8 ≥ 135,000 Btu/h
3b, 3c, 4b, 4c, 5b, 5c, 6b ≥ 65,000 Btu/h

Table 6.5.1-3 Eliminate Required Economizer for Comfort Cooling by Increasing Cooling Efficiency

Climate Zone Efficiency Improvementa
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 IPLV, IEER, or SEER then to eliminate the required air or water economizer, the minimum cooling efficiency of the HVAC unit must be increased by the percentage shown. If the HVAC unit is only rated with a full-load metric like EER cooling then these must be increased by the percentage shown.

Air economizer systems shall be capable of modulating outdoor air and return air dampers to provide up to 100% of the design supply air quantity as outdoor air for cooling.
Economizer dampers shall be capable of being sequenced with the mechanical cooling equipment and shall not be controlled by only mixed-air temperature.

Exception: The use of mixed-air temperature limit control shall be permitted for systems controlled from space temperature (such as single-zone systems).

All air economizers shall be capable of automatically reducing outdoor air intake to the design minimum outdoor air quantity when outdoor air intake will no longer reduce cooling energy usage. High-limit shutoff control types and associated setpoints for specific climate zones shall be chosen from Table 6.5.1.1.3.

TABLE 6.5.1.1.3 High-Limit Shutoff Control Settings for Air Economizersb

Control Type Allowed Only in Climate Zone at Listed Setpoint Required High-Limit Setpoints (Economizer Off When):
Equation Description
Fixed dry-bulb temperature 1b, 2b, 3b, 3c, 4b, 4c, 5b, 5c, 6b, 7, 8 TOA > 75°F Outdoor air temperature exceeds 75°F
5a, 6a TOA > 70°F Outdoor air temperature exceeds 70°F
1a, 2a, 3a, 4a, TOA > 65°F Outdoor air temperature exceeds 65°F
Differential dry-bulb temperature 1b, 2b, 3b, 3c, 4b, 4c, 5a, 5b, 5c, 6a, 6b, 7, 8 TOA > TRA Outdoor air temperature exceeds return air temperature
Fixed enthalpy with fixed dry-bulb temperature All hOA > 28 Btu/lba or TOA > 75°F Outdoor air enthalpy exceeds 28 Btu/lba of dry aira or outdoor air temperature exceeds 75°F
Differential enthalpy with fixed dry-bulb temperature All hOA > hRA or TOA > 75°F Outdoor air enthalpy exceeds return air enthalpy or outdoor air temperature exceeds 75°F
  1. At altitudes substantially different than sea level, the fixed enthalpy limit shall be set to the enthalpy value at 75°F and 50% RH. As an example, at approximately 6000 ft elevation, the fixed enthalpy limit is approximately 30.7 Btu/lb.
  2. Devices with selectable rather than adjustable setpoints shall be capable of being set to within 2°F and 2 Btu/lb of the setpoint listed.
Return, exhaust/relief, and outdoor air dampers shall meet the requirements of Section 6.4.3.4.3.
Systems shall provide a means to relieve excess outdoor air during air economizer operation to prevent overpressurizing the building. The relief air outlet shall be located so as to avoid recirculation into the building.
Outdoor air, return air, mixed air, and supply air sensors shall be calibrated within the following accuracies:
  1. Dry-bulb and wet-bulb temperatures shall be accurate to ±2°F over the range of 40°F to 80°F.
  2. Enthalpy and the value of a differential enthalpy sensor shall be accurate to ±3 Btu/lb over the range of 20 to 36 Btu/lb.
  3. Relative humidity shall be accurate to ±5% over the range of 20% to 80% RH.
Water economizer systems shall be capable of cooling supply air by indirect evaporation and providing up to 100% of the expected system cooling load at outdoor air temperatures of 50°F dry bulb/45°F wet bulb and below.

Exceptions:

  1. Systems primarily serving computer rooms in which 100% of the expected system cooling load at the dry-bulb and wet-bulb listed in Table 6.5.1.2.1 is met with evaporative water economizers
  2. Systems primarily serving computer rooms in which 100% of the expected system cooling load at the dry-bulb temperatures listed in Table 6.5.1.2.1 is met with dry cooler water economizers
  3. Systems where dehumidification requirements cannot be met using outdoor air temperatures of 50°F dry-bulb/45°F wet-bulb and where 100% of the expected system cooling load at 45°F dry-bulb/40°F wet-bulb is met with evaporative water economizers

TABLE 6.5.1.2.1 Water Economizer Sizing Dry-Bulb and Wet-Bulb Requirements for Computer Rooms

Zone Evaporative Water Economizer Dry Cooler Water Economizer
Dry Bulb, °F Wet Bulb, °F Dry Bulb, °F
1 A NR NR
1 B NR NR
2 A 40.0 35.0 30.0
2 B 35.0 30.0 30.0
3 A 40.0 35.0 25.0
3 B 30.0 25.0 25.0
3 C 30.0 25.0 30.0
4 A 40.0 35.0 25.0
4 B 30.0 25.0 25.0
4 C 30.0 25.0 25.0
5 A 40.0 35.0 20.0
5 B 30.0 25.0 20.0
5 C 30.0 25.0 25.0
6 A 35.0 30.0 20.0
6 B 30.0 25.0 20.0
7 30.0 25.0 20.0
8 30.0 25.0 20.0

NR—Not required

Precooling coils and water-to-water heat exchangers used as part of a water economizer system shall either have a water-side pressure drop of less than 15 ft of water, or a secondary loop shall be created so that the coil or heat exchanger pressure drop is not seen by the circulating pumps when the system is in the normal cooling (noneconomizer) mode.
Economizer systems shall be integrated with the mechanical cooling system and be capable of providing partial cooling even when additional mechanical cooling is required to meet the remainder of the cooling load. Controls shall not false load the mechanical cooling systems by limiting or disabling the economizer or by any other means, such as hot gas bypass, except at the lowest stage of mechanical cooling.

Units that include an air economizer shall comply with the following:

  1. Unit controls shall have the mechanical cooling capacity control interlocked with the air economizer controls such that the outdoor air damper is at the 100% open position when mechanical cooling is on, and the outdoor air damper does not begin to close to prevent coil freezing due to minimum compressor run time until the leaving air temperature is less than 45°F.
  2. DX units that control the capacity of the mechanical cooling directly based on occupied space temperature shall have a minimum of two stages of mechanical cooling capacity per the following effective dates:

    ≥75,000 Btu/h Rated Capacity—Effective 1/1/2014
    ≥65,000 Btu/h Rated Capacity—Effective 1/1/2016

  3. Effective 1/1/2014, all other DX units, including those that control space temperature by modulating the airflow to the space, shall comply with the requirements of Table 6.5.1.3.

    TABLE 6.5.1.3 DX Cooling Stage Requirements for Modulating Airflow Units

    Rating Capacity, Btu/h Minimum Number of Mechanical Cooling Stages Minimum Compressor Displacementa
    ≥65,000 and <240,000 3 ≤35% of full load
    ≥240,000 4 ≤25% full load
    a. For mechanical cooling stage control that does not use variable compressor displacement the percent displacement shall be equivalent to the mechanical cooling capacity reduction evaluated at the full load rating conditions for the compressor.
HVAC system design and economizer controls shall be such that economizer operation does not increase the building heating energy use during normal operation.

Exceptions: Economizers on VAV systems that cause zone-level heating to increase due to a reduction in supply air temperature

Systems with hydronic cooling and humidification systems designed to maintain inside humidity at a dew-point temperature greater than 35°F shall use a water economizer if an economizer is required by Section 6.5.1.
Zone thermostatic controls shall prevent
  1. reheating;
  2. recooling;
  3. 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; and
  4. other simultaneous operation of heating and cooling systems to the same zone.

Exceptions:

  1. Zones without DDC for which the volume of air that is reheated, recooled, or mixed is less than the larger of the following:
    1. 30% of the zone design peak supply rate
    2. The outdoor airflow rate required to meet the ventilation requirements of ASHRAE Standard 62.1 for the zone
    3. 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 for the system
    4. The airflow rate required to comply with applicable codes or accreditation standards, such as pressure relationships or minimum air change rates
  2. Zones with DDC that comply with all of the following:
    1. The airflow rate in dead band between heating and cooling does not exceed the larger of the following:
      1. 20% of the zone design peak supply rate
      2. The outdoor airflow rate required to meet the ventilation requirements of ASHRAE Standard 62.1 for the zone
      3. 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
      4. The airflow rate required to comply with applicable codes or accreditation standards, such as pressure relationships or minimum air change rates
    2. The airflow rate that is reheated, recooled, or mixed shall be less than 50% of the zone design peak supply rate.
    3. 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.
    4. 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

Where reheating is permitted by other parts of this standard, zones that have both supply and return/exhaust air openings greater than 6 ft above floor shall not supply heating air more than 20°F above the space temperature setpoint.

Exceptions:

  1. Laboratory exhaust systems that comply with Section 6.5.7.2.
  2. During preoccupancy building warm-up and setback
The heating of fluids in hydronic systems that have been previously mechanically cooled and the cooling of fluids that have been previously mechanically heated shall be limited in accordance with Sections 6.5.2.2.1 through 6.5.2.2.3.
Hydronic systems that use a common return system for both hot water and chilled water shall not be used.
Systems that use a common distribution system to supply both heated and chilled water are acceptable provided all of the following are met:
  1. The system is designed to allow a dead band between changeover from one mode to the other of at least 15°F outdoor air temperature.
  2. The system is designed to operate and is provided with controls that will allow operation in one mode for at least four hours before changing over to the other mode.
  3. Reset controls are provided that allow heating and cooling supply temperatures at the changeover point to be no more than 30°F apart.
Hydronic heat pumps connected to a common heat-pump water loop with central devices for heat rejection (e.g., cooling tower) and heat addition (e.g., boiler) shall have the following:
  1. Controls that are capable of providing a heat-pump water supply temperature dead band of at least 20°F between initiation of heat rejection and heat addition by the central devices (e.g., tower and boiler).
  2. For Climate Zones 3 through 8, if a closed-circuit tower (fluid cooler) is used, either an automatic valve shall be installed to bypass all but a minimal flow of water around the tower (for freeze protection) or low-leakage positive closure dampers shall be provided. If an open-circuit tower is used directly in the heat-pump loop, an automatic valve shall be installed to bypass all heat-pump water flow around the tower. If an open-circuit tower is used in conjunction with a separate heat exchanger to isolate the tower from the heat-pump loop, then heat loss shall be controlled by shutting down the circulation pump on the cooling tower loop.

Exception: Where a system loop temperature optimization controller is used to determine the most efficient operating temperature based on real-time conditions of demand and capacity, dead bands of less than 20°F shall be allowed.

Where humidity controls are provided, such controls shall prevent reheating, mixing of hot and cold airstreams, or other means of simultaneous heating and cooling of the same airstream.

Exceptions:

  1. The system is configured to reduce supply air volume to 50% or less of the design airflow rate or the minimum outdoor air ventilation rate specified in ASHRAE Standard 62.1 or other applicable federal, state, or local code or recognized standard, whichever is larger, before simultaneous heating and cooling takes place.
  2. The individual fan cooling unit has a design cooling capacity of 65,000 Btu/h or less and is capable of unloading to 50% capacity before simultaneous heating and cooling takes place.
  3. The individual mechanical cooling unit has a design cooling capacity of 40,000 Btu/h or less. An individual mechanical cooling unit is a single system composed of a fan or fans and a cooling coil capable of providing mechanical cooling.
  4. Systems serving spaces where specific humidity levels are required to satisfy process needs, such as vivariums, museums, surgical suites, pharmacies, and buildings with refrigerating systems, such as supermarkets, refrigerated warehouses, and ice arenas, and the building includes site-recovered or site solar energy source that provide energy equal to at least 75% of the annual energy for reheating or for providing warm air in mixing systems. This exception does not apply to computer rooms.
  5. At least 90% of the annual 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.
  6. Systems where the heat added to the airstream is the result of the use of a desiccant system and 75% of the heat added by the desiccant system is removed by a heat exchanger, either before or after the desiccant system with energy recovery.
Humidifiers with preheating jackets mounted in the airstream shall be provided with an automatic valve to shut off preheat when humidification is not required.
Humidification system dispersion tube hot surfaces in the airstreams of ducts or air-handling units shall be insulated with a product with an insulating value of at least R-0.5.

Exception: Systems where mechanical cooling, including economizer operation, does not occur simultaneously with humidification

Preheat coils shall have controls that stop their heat output whenever mechanical cooling, including economizer operation, is occurring.
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.

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 ≤ cfmS • 0.0011 hp ≤ cfmS • 0.0015
Option 2: Fan system bhp Allowable fan system bhp bhp ≤ cfmS • 0.00094 + A bhp ≤ cfmS • 0.0013 + 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

TABLE 6.5.3.1-2 Fan Power Limitation Pressure Drop Adjustment

Device Adjustment
Credits
Fully ducted return and/or exhaust air systems 0.5 in. wc (2.15 in. wc for laboratory and vivarium systems)
Return and/or exhaust airflow control devices 0.5 in. wc
Exhaust filters, scrubbers, or other exhaust treatment The pressure drop of device calculated at fan system design condition
Particulate Filtration Credit: MERV 9 through 12 0.5 in. wc
Particulate Filtration Credit: MERV 13 through 15 0.9 in. wc
Particulate Filtration Credit: MERV 16 and greater and electronically enhanced filters Pressure drop calculated at 2× clean filter pressure drop at fan system design condition
Carbon and other gas-phase air cleaners Clean filter pressure drop at fan system design condition
Biosafety cabinet Pressure drop of device at fan system design condition
Energy recovery device, other than coil runaround loop (2.2 × Energy Recovery Effectiveness) — 0.5 in. wc for each airstream
Coil runaround loop 0.6 in. wc for each airstream
Evaporative humidifier/cooler in series with another cooling coil Pressure drop of device at fan system design condition
Sound attenuation section (fans serving spaces with design background noise goals below NC35) 0.15 in. wc
Exhaust system serving fume hoods 0.35 in. wc
Laboratory and vivarium exhaust systems in high-rise buildings 0.25 in. wc/100 ft of vertical duct exceeding 75 ft
Deductions
Systems without central cooling device —0.6 in. wc
Systems without central heating device —0.3 in. wc
Systems with central electric resistance heat —0.2 in. wc
Each HVAC system at fan system design conditions shall not exceed the allowable fan system motor nameplate hp (Option 1) or fan system bhp (Option 2) as shown in Table 6.5.3.1-1. This includes supply fans, return/ relief fans, exhaust fans, and fan-powered terminal units associated with systems providing heating or cooling capability. Single-zone variable-air-volume systems shall comply with the constant-volume fan power limitation.

Exceptions:

  1. Hospital, vivarium, and laboratory systems that utilize flow control devices on exhaust and/or return to maintain space pressure relationships necessary for occupant health and safety or environmental control may use variable-volume fan power limitation.
  2. Individual exhaust fans with motor nameplate horsepower of 1 hp or less.
For each fan, the selected fan motor shall be no larger than the first available motor size greater than the bhp. The fan bhp must be indicated on the design documents to allow for compliance verification by the code official.

Exceptions:

  1. For fans less than 6 bhp, where the first available motor larger than the bhp has a nameplate rating within 50% of the bhp, the next larger nameplate motor size may be selected.
  2. For fans 6 bhp and larger, where the first available motor larger than the bhp has a nameplate rating within 30% of the bhp, the next larger nameplate motor size may be selected.
  3. Systems complying with Section 6.5.3.1.1, Option 1.
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 15 percentage points of the maximum total efficiency of the fan.

Exceptions:

  1. Single fans with a motor nameplate horsepower of 5 hp or less
  2. Multiple fans in series or parallel (e.g., fan arrays) that have a combined motor nameplate horsepower 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 thirdparty-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
Each cooling system listed in Table 6.5.3.2.1 shall be designed to vary the indoor fan airflow as a function of load and shall comply with the following requirements:
  1. DX and chilled-water cooling units that control the capacity of the mechanical cooling directly based on space temperature shall have a minimum of two stages of fan control. Low or minimum speed shall not exceed 66% of full speed. At low or minimum speed, the fan system shall draw no more than 40% of the fan power at full fan speed. Low or minimum speed shall be used during periods of low cooling load and ventilation-only operation.
  2. All other units, including DX cooling units and chilled-water units that control the space temperature by modulating the airflow to the space, shall have modulating fan control. Minimum speed shall not exceed 50% of full speed. At minimum speed, the fan system shall draw no more than 30% of the power at full fan speed. Low or minimum speed shall be used during periods of low cooling load and ventilation-only operation.
  3. Units that include an air-side economizer to meet the requirements of Section 6.5.1 shall have a minimum of two speeds of fan control during economizer operation.

Exceptions:

  1. Modulating fan control is not required for chilled-water and evaporative cooling units with <1 hp fan motors if the units are not used to provide ventilation air and the indoor fan cycles with the load.
  2. If the volume of outdoor air required to meet the ventilation requirements of Standard 62.1 at low speed exceeds the air that would be delivered at the speed defined in Section 6.5.3.2.1(a) or 6.5.3.2.1(b) then the minimum speed shall be selected to provide the required ventilation air.

TABLE 6.5.3.2.1 Effective Dates for Fan Control

Cooling System Type Fan Motor Size, hp Mechanical Cooling Capacity, Btu/h Effective Date
DX cooling Any ≥110,000
≥75,000 1/1/2014
≥65,000 1/1/2016
Chilled-water and evaporative cooling ≥5 Any
≥1/4 Any 1/1/2014
Static pressure sensors used to control VAV fans shall be located such that the controller setpoint is no greater than 1.2 in. wc If this results in the sensor being located downstream of major duct splits, sensors shall be installed in each major branch to ensure that static pressure can be maintained in each.

Exception: Systems complying with Section 6.5.3.2.3

For systems with DDC of individual zones reporting to the central control panel, static pressure setpoint shall be reset based on the zone requiring the most pressure; i.e., the setpoint is reset lower until one zone damper is nearly wide open. Controls shall provide the following:
  1. Monitor zone damper positions or other indicator of need for static pressure
  2. Automatically detect those zones that may be excessively driving the reset logic and generate an alarm to the system operator
  3. Readily allow operator removal of zone(s) from the reset algorithm
Multiple-zone VAV systems with DDC of individual zone boxes reporting to a central control panel shall include means to automatically reduce outdoor air intake flow below design rates in response to changes in system ventilation efficiency as defined by Appendix A of ASHRAE Standard 62.1.

Exceptions:

  1. VAV systems with zonal transfer fans that recirculate air from other zones without directly mixing it with outdoor air, dual-duct dual-fan VAV systems, and VAV systems with fan-powered terminal units
  2. Systems required to have the exhaust air energy recovery complying with Section 6.5.6.1
  3. Systems where total design exhaust airflow is more than 70% of total design outdoor air intake flow requirements
Multiple zone HVAC systems must include controls that automatically reset the supply air temperature in response to representative building loads, or to outdoor air temperature. The controls shall reset the supply air temperature at least 25% of the difference between the design supply air temperature and the design room air temperature. Controls that adjust the reset based on zone humidity are allowed. Zones that are expected to experience relatively constant loads, such as electronic equipment rooms, shall be designed for the fully reset supply temperature.

Exceptions:

  1. Climate Zones 1a, 2a, and 3a
  2. Systems that prevent reheating, recooling, or mixing of heated and cooled supply ai.
  3. Systems in which at least 75% of the energy for reheating (on an annual basis) is from site recovered or site solar energy sources
Motors for fans that are 1/12 hp or greater and less than 1 hp shall be electronically-commutated motors or shall have a minimum motor efficiency of 70% when rated in accordance with DOE 10 CFR 431. These motors shall also have the means to adjust motor speed for either balancing or remote control. Belt-driven fans may use sheave adjustments for airflow balancing in lieu of a varying motor speed.

Exceptions:

  1. Motors in the airstream within fan-coils and terminal units that operate only when providing heating to the space served
  2. Motors installed in space conditioning equipment certified under Section 6.4.1
  3. Motors covered by Table 10.8-4 or 10.8-5
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.

TABLE 6.5.4.1 Boiler Turndown

Boiler System Design Input, Btu/h Minimum Turndown Ratio
≥1,000,000 and ≤5,000,000 3 to 1
>5,000,000 and ≤10,000,000 4 to 1
>10,000,000 5 to 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.

HVAC pumping systems having a total pump system power exceeding 10 hp that include 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 reducing pump flow rates to 50% or less of the design flow rate. Individual chilled-water pumps serving variable-flow systems having motors exceeding 5 hp shall have controls and/or devices (such as variable-speed control) that will result in pump motor demand of no more than 30% of design wattage at 50% of design water flow. The controls or devices shall be controlled as a function of desired flow or to maintain a minimum required differential pressure. Differential pressure shall be measured at or near the most remote heat exchanger or the heat exchanger requiring the greatest differential pressure. The differential pressure setpoint shall be no more than 110% of that required to achieve design flow through the heat exchanger. Where differential pressure control is used to comply with this section and DDC systems are used, the setpoint shall be reset downward based on valve positions until one valve is nearly wide open.

Exceptions:

  1. Systems where the minimum flow is less than the minimum flow required by the equipment manufacturer for the proper operation of equipment served by the system, such as chillers, and where total pump system power is 75 hp or less
  2. Systems that include no more than three control valves
When a chilled-water plant includes more than one chiller, provisions shall be made so that all fluid flow through the chiller is automatically shut off when the chiller is shut down. Chillers piped in series for the purpose of increased temperature differential shall be considered as one chiller. Where constant-speed chilled-water or condenser water pumps are used to serve multiple chillers, the number of pumps shall be no less than the number of chillers and staged on and off with the chillers.
When a boiler plant includes more than one boiler, provisions shall be made so that the flow through the boiler is automatically shut off when the boiler is shut down. Where constant-speed hot-water pumps are used to serve multiple boilers, the number of pumps shall be no less than the number of boilers and staged on and off with the boilers.
Chilled- and hot-water systems with a design capacity exceeding 300,000 Btu/h supplying chilled or heated water (or both) to comfort conditioning systems shall include controls that automatically reset supply water temperatures by representative building loads (including return water temperature) or by outdoor air temperature.

Exceptions:

  1. Where the supply temperature reset controls cannot be implemented without causing improper operation of heating, cooling, humidifying, or dehumidifying systems
  2. Hydronic systems, such as those required by Section 6.5.4.1, that use variable flow to reduce pumping energy
Each hydronic heat pump and water-cooled unitary air-conditioner shall have a two-position automatic valve interlocked to shut off water flow when the compressor is off.

Exception: Units employing water economizer

Hydronic heat pumps and water-cooled unitary air-conditioners having a total pump system power exceeding 5 hp shall have controls and/or devices (such as variable-speed control) that will result in pump motor demand of no more than 30% of design wattage at 50% of design water flow.
All chilled-water and condenser-water piping shall be designed such that the design flow rate in each piping segment shall not exceed the values listed in Table 6.5.4.6 for the appropriate total annual hours of operation. Piping size selections for systems that operate under variable flow conditions (e.g., modulating two-way control valves at coils) and that contain variable-speed pump motors are allowed to be made from the "Variable Flow/Variable Speed" columns. All others shall be made from the "Other" columns.

Exceptions:

  1. Design flow rates exceeding the values in Table 6.5.4.6 are allowed in specific sections of piping if the piping in question is not in the critical circuit at design conditions and is not predicted to be in the critical circuit during more than 30% of operating hours.
  2. Piping systems that have equivalent or lower total pressure drop than the same system constructed with standard weight steel pipe with piping and fittings sized per Table 6.5.4.6

TABLE 6.5.4.6 Piping System Design Maximum Flow Rate in GPM

Operating Hours/Year ≤2000 Hours/Year >2000 and ≤4400 Hours/Year >4400 Hours/Year
Nominal Pipe Size, in. Other Variable Flow/Variable Speed Other Variable Flow/Variable Speed Other Variable Flow/Variable Speed
2 1/2 120 180 85 130 68 110
3 180 270 140 210 110 170
4 350 530 260 400 210 320
5 410 620 310 470 250 370
6 740 1100 570 860 440 680
8 1200 1800 900 1400 700 1100
10 1800 2700 1300 2000 1000 1600
12 2500 3800 1900 2900 1500 2300
Maximum velocity for pipes over 14—24 in. in size 8.5 ft/s 13.0 ft/s 6.5 ft/s 9.5 ft/s 5.0 ft/s 7.5 ft/s
Section 6.5.5 applies to heat rejection equipment used in comfort cooling systems, such as air-cooled condensers, dry coolers, open-circuit cooling towers, closed-circuit cooling towers, and evaporative condensers.

Exception: Heat rejection devices whose energy usage is included in the equipment efficiency ratings listed in Tables 6.8.1-1 through 6.8.1-4

Each fan powered by a motor of 7.5 hp or larger shall have the capability to operate at two-thirds full speed or less and shall have controls that automatically change the fan speed to control the leaving fluid temperature or condensing temperature/pressure of the heat rejection device.

Exceptions:

  1. Condenser fans serving multiple refrigerant circuits
  2. Condenser fans serving flooded condensers
  3. Installations located in Climate Zones 1 and 2
Multicell heat rejection equipment with variable-speed fan drives shall
  1. operate the maximum number of fans allowed that comply with the manufacturer's requirements for all system components and
  2. control all fans to the same fan speed required for the instantaneous cooling duty, as opposed to staged (on/off) operation. Minimum fan speed shall comply with the minimum allowable speed of the fan drive system per the manufacturer's recommendations.
Centrifugal fan open-circuit cooling towers with a combined rated capacity of 1100 gpm or greater at 95°F condenser water return, 85°F condenser water supply, and 75°F outdoor air wet-bulb temperature shall meet the energy efficiency requirement for axial fan open-circuit cooling towers listed in Table 6.8.1-7.

Exception: Centrifugal open-circuit cooling towers that are ducted (inlet or discharge) or require external sound attenuation.

Open-circuit cooling towers used on water-cooled chiller systems that are configured with multiple- or variable-speed condenser water pumps shall be designed so that all open-circuit cooling tower cells can be run in parallel with the larger of
  1. the flow that is produced by the smallest pump at its minimum expected flow rate or
  2. 50% of the design flow for the cell.
Each fan system shall have an energy recovery system when the system's supply 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.

TABLE 6.5.6.1-1 Exhaust Air Energy Recovery Requirements for Ventilation Systems Operating Less than 8000 Hours per Year

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
1B, 2B,5C NR NR NR NR ≥26000 ≥12000 ≥5000 ≥4000
6B ≥28,000 ≥26,500 ≥11000 ≥5500 ≥4500 ≥3500 ≥ 2500 ≥1500
1A, 2A, 3A, 4A, 5A, 6A ≥26,000 ≥16,000 ≥5500 ≥4500 ≥3500 ≥2000 ≥1000 >0
7,8 ≥4500 ≥4000 ≥2500 ≥1000 >0 >0 >0 >0

NR—Not required

TABLE 6.5.6.1-2 Exhaust Air Energy Recovery Requirements for Ventilation Systems Operating Greater than or Equal to 8000 Hours per Year

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
1B, 2B,3B, 4C, 5C NR ≥19,500 ≥9000 ≥5000 ≥4000 ≥3000 ≥1500 >0
1A, 2A, 3A, 4B, B ≥2500 ≥2000 ≥1000 ≥500 >0 >0 >0 >0
4A, 5A, 6A, 6B, 7, 8 >0 >0 >0 >0 >0 >0 >0 >0

NR—Not required

Energy recovery systems required by this section shall have at least 50% energy recovery effectiveness. Fifty percent energy recovery effectiveness shall mean a change in the enthalpy of the outdoor air supply equal to 50% 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. Heating energy recovery in Climate Zones 1 and 2.
  7. Cooling energy recovery in Climate Zones 3c, 4c, 5b, 5c, 6b, 7, and 8
  8. 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.
  9. Systems requiring dehumidification that employ energy recovery in series with the cooling coil
  10. Systems expected to operate less than 20 hours per week at the outdoor air percentage covered by Table 6.5.6.1-1
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.
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:

  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 or site-recovered energy or from other sources
Replacement air introduced directly into the hood cavity of kitchen exhaust hoods shall not exceed 10% of the hood exhaust airflow rate.
Conditioned supply air delivered to any space with a kitchen hood shall not exceed the greater of
  1. the supply flow required to meet the space heating or cooling load or
  2. the hood exhaust flow minus the available transfer air from adjacent spaces. Available transfer air is that portion of outdoor ventilation air not required to satisfy other exhaust needs, such as restrooms, and not required to maintain pressurization of adjacent spaces
If a kitchen/dining facility has a total kitchen hood exhaust airflow rate greater than 5000 cfm then each hood shall have an exhaust rate that complies with Table 6.5.7.1.3. If a single hood or hood section is installed over appliances with different duty ratings, then the maximum allowable flow rate for the hood or hood section shall not exceed the Table 6.5.7.1.3 values 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: At least 75% of all the replacement air is transfer air that would otherwise be exhausted.

TABLE 6.5.7.1.3 Maximum Net Exhaust Flow Rate, cfm per Linear Foot of Hood Length

Type of Hood Light Duty Equipment Medium Duty Equipment Heavy Duty Equipment Extra Heavy Duty Equipment
Wall-mounted canopy 140 210 280 385
Single island 280 350 420 490
Double island (per side) 175 210 280 385
Eyebrow 175 175 NA NA
Backshelf/pass-over 210 210 280 NA

NA = not allowed

If a kitchen/dining facility has a total kitchen hood exhaust airflow rate greater than 5000 cfm then it shall have one of the following:
  1. At least 50% of all replacement air is transfer air that would otherwise be exhausted.
  2. Demand ventilation system(s) on at least 75% of the exhaust air. Such systems shall be capable of at least 50% reduction in exhaust and replacement air system airflow rates, including controls necessary 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. Listed energy recovery devices with a sensible heat recovery effectiveness of not less than 40% on at least 50% of the total exhaust airflow.
An approved field test method shall be used to evaluate design airflow rates and demonstrate proper capture and containment performance of installed commercial kitchen exhaust systems. Where demand ventilation systems are utilized to meet Section 6.5.7.1.4, additional performance testing shall be required to demonstrate proper capture and containment at minimum airflow.
Buildings with laboratory exhaust systems having a total exhaust rate greater than 5000 cfm shall include at least one of the following features:
  1. VAV laboratory exhaust and room supply system capable of reducing exhaust and makeup airflow rates and/or incorporate a heat recovery system to precondition makeup air from laboratory exhaust that shall meet the following:

    A + B × (E/M) ≥ 50%

    where

    A = percentage that the exhaust and makeup airflow rates can be reduced from design conditions
    B = percentage sensible recovery effectiveness
    E = exhaust airflow rate through the heat recovery device at design conditions
    M = makeup airflow rate of the system at design conditions.
  2. VAV laboratory exhaust and room supply systems that are required to have minimum circulation rates to comply with code or accreditation standards shall be capable of reducing zone exhaust and makeup airflow rates to the regulated minimum circulation values or the minimum required to maintain pressurization relationship requirements. Nonregulated zones shall be capable of reducing exhaust and makeup airflow rates to 50% of the zone design values or the minimum required to maintain pressurization relationship requirements.
  3. Direct makeup (auxiliary) air supply equal to at least 75% of the exhaust airflow rate, heated no warmer than 2°F below room setpoint, cooled to no cooler than 3°F above room setpoint, no humidification added, and no simultaneous heating and cooling used for dehumidification control.
Radiant heating shall be used when heating is required for unenclosed spaces.

Exception: Loading docks equipped with air curtains

Radiant heating systems that are used as primary or supplemental enclosed space heating must be in conformance with the governing provisions of the standard, including, but not limited to, the following:
  1. Radiant hydronic ceiling or floor panels (used for heating or cooling)
  2. Combination or hybrid systems incorporating radiant heating (or cooling) panels
  3. Radiant heating (or cooling) panels used in conjunction with other systems such as VAV or thermal storage systems
Cooling systems shall not use hot gas bypass or other evaporator pressure control systems unless the system is designed with multiple steps of unloading or continuous capacity modulation. The capacity of the hot gas bypass shall be limited as indicated in Table 6.5.9 for VAV units and single-zone VAV units. Hot gas bypass shall not be used on constant-volume units.

TABLE 6.5.9 Hot-Gas Bypass Limitation

Rated Capacity Maximum Hot-Gas Bypass, % of Total Capacity
≤240,000 Btu/h 15%
>240,000 Btu/h 10%
Any conditioned space with a door, including doors with more than one-half glass, opening to the outdoors shall be provided with controls that, when any such door is open,
  1. disable mechanical heating or reset the heating setpoint to 55°F or lower within five minutes of the door opening and
  2. disable mechanical cooling or reset the cooling setpoint to 90°F or greater within five minutes of the door opening. Mechanical cooling may remain enabled if outdoor air temperature is below space temperature.

Exceptions:

  1. Building entries with automatic closing devices
  2. Any space without a thermostat
  3. Alterations to existing buildings
  4. Loading docks
Refrigeration systems that are comprised of refrigerated display cases, walk-in coolers, or walk-in freezers connected to remote compressors, remote condensers, or remote condensing units shall meet the requirements of Sections 6.5.11.1 through 6.5.11.2.

Exception: Systems utilizing transcritical refrigeration cycle or ammonia refrigerant

Fan-powered condensers shall conform to the following requirements:
  1. Design saturated condensing temperatures for air-cooled condensers shall be less than or equal to the design dry-bulb temperature plus 10°F for low-temperature refrigeration systems and less than or equal to the design dry-bulb temperature plus 15°F for medium-temperature refrigeration systems.
    1. Saturated condensing temperature for blend refrigerants shall be determined using the average of liquid and vapor temperatures as converted from the condenser drain pressure.
  2. Condenser fan motors that are less than 1 hp shall use electronically commutated motors, permanent split capacitor-type motors, or three-phase motors.
  3. All condenser fans for air-cooled condensers, evaporatively cooled condensers, and air- or water-cooled fluid coolers or cooling towers shall incorporate one of the following continuous variable-speed fan-control approaches and shall reduce fan motor demand to no more than 30% of design wattage at 50% of design air volume:
    1. Refrigeration system condenser control for air-cooled condensers shall use variable setpoint control logic to reset the condensing temperature setpoint in response to ambient dry-bulb temperature.
    2. Refrigeration system condenser control for evaporatively cooled condensers shall use variable setpoint control logic to reset the condensing temperature setpoint in response to ambient wet-bulb temperature.
  4. Multiple fan condensers shall be controlled in unison.
  5. The minimum condensing temperature setpoint shall be no greater than 70°F.
Refrigeration compressor systems shall conform to the following requirements:
  1. Compressors and multiple-compressor systems suction groups shall include control systems that use floating suction pressure control logic to reset the target suction pressure temperature based on the temperature requirements of the attached refrigeration display cases or walk-ins.

    Exceptions:

    1. Single-compressor systems that do not have variable capacity capability
    2. Suction groups that have a design saturated suction temperature equal to or greater than 30°F, suction groups that comprise the high stage of a two-stage or cascade system, or suction groups that primarily serve chillers for secondary cooling fluids.
  2. Liquid subcooling shall be provided for all low-temperature compressor systems with a design cooling capacity equal to or greater than 100,000 Btu/h with a design saturated suction temperature equal to or less than —10°F. The subcooled liquid temperature shall be controlled at a maximum temperature setpoint of 50°F at the exit of the subcooler using either compressor economizer (interstage) ports or a separate compressor suction group operating at a saturated suction temperature equal to or greater than 18°F.
    1. Subcooled liquid lines are subject to the insulation requirements of Table 6.8.3-2.
  3. All compressors that incorporate internal or external crankcase heaters shall provide a means to cycle the heaters off during compressor operation.
HVAC systems serving the heating, cooling, or ventilating needs of a computer room shall comply with Sections 6.1, 6.4, 6.6.1.1 or 6.6.1.2, 6.6.1.3, 6.7, and 6.8.

TABLE 6.6.1 Power Usage Effectiveness (PUE) Maximum

Climate Zone PUEa
1A 1.61
2A 1.49
3A 1.41
4A 1.36
5A 1.36
6A 1.34
1B 1.53
2B 1.45
3B 1.42
4B 1.38
5B 1.33
6B 1.33
3C 1.39
4C 1.38
5C 1.36
7 1.32
8 1.30

a. PUE0 and PUE1 shall not include energy for battery charging.

The computer room PUE1 shall be less than or equal to the values listed in Table 6.6.1. Hourly simulation of the proposed design, for purposes of calculating PUE1, shall be based on the ASHRAE Standard 90.1 Appendix G simulation methodology.

Exceptions: This compliance path is not allowed for a proposed computer room design utilizing a combined heat and power system.

The computer room PUE0 is less than or equal to the values listed in Table 6.6.1, shall be the highest value determined at outdoor cooling design temperatures, and shall be limited to systems only utilizing electricity for an energy source. PUE0 shall be calculated for two conditions: 100% design IT equipment energy and 50% design IT equipment energy.
Documentation shall be provided, including a breakdown of energy consumption or demand by at least the following components: IT equipment, power distribution losses external to the IT equipment, HVAC systems, and lighting.
The authority having jurisdiction may require submittal of compliance documentation and supplemental information in accordance with Section 4.2.2 of this standard.
The following requirements are mandatory provisions and are necessary for compliance with the standard.
Construction documents shall require that, within 90 days after the date of system acceptance, record drawings of the actual installation be provided to the building owner or the designated representative of the building owner. Record drawings shall include, as a minimum, the location and performance data on each piece of equipment; general configuration of the duct and pipe distribution system, including sizes; and the terminal air or water design flow rates.
Construction documents shall require that an operating manual and a maintenance manual be provided to the building owner or the designated representative of the building owner within 90 days after the date of system acceptance. These manuals shall be in accordance with industry-accepted standards (see Informative Appendix E) and shall include, at a minimum, the following:
  1. Submittal data stating equipment size and selected options for each piece of equipment requiring maintenance.
  2. Operation manuals and maintenance manuals for each piece of equipment and system requiring maintenance, except equipment not furnished as part of the project. Required routine maintenance actions shall be clearly identified.
  3. Names and addresses of at least one service agency.
  4. HVAC controls system maintenance and calibration information, including wiring diagrams, schematics, and control sequence descriptions. Desired or field-determined setpoints shall be permanently recorded on control drawings at control devices or, for digital control systems, in programming comments.
  5. A complete narrative of how each system is intended to operate, including suggested setpoints.
Construction documents shall require that all HVAC systems be balanced in accordance with generally accepted engineering standards (see Informative Appendix E). Construction documents shall require that a written balance report be provided to the building owner or the designated representative of the building owner for HVAC systems serving zones with a total conditioned area exceeding 5000 ft2.
Air systems shall be balanced in a manner to first minimize throttling losses. Then, for fans with fan system power greater than 1 hp, fan speed shall be adjusted to meet design flow conditions.
Hydronic systems shall be proportionately balanced in a manner to first minimize throttling losses; then the pump impeller shall be trimmed or pump speed shall be adjusted to meet design flow conditions.

Exceptions: Impellers need not be trimmed nor pump speed adjusted

  1. for pumps with pump motors of 10 hp or less or
  2. when throttling results in no greater than 5% of the nameplate horsepower draw, or 3 hp, whichever is greater, above that required if the impeller was trimmed.

6.7.2.4 System Commissioning

AMENDMENT
This section has been amended at the state or city level.
HVAC control systems shall be tested to ensure that control elements are calibrated, adjusted, and in proper working condition. For projects larger than 10,000 ft2, conditioned area, except warehouses and semiheated spaces, detailed instructions for commissioning HVAC systems (see Informative Appendix E) shall be provided by the designer in plans and specifications.

TABLE 6.8.1-1 Electrically Operated Unitary Air Conditioners and Condensing Units—Minimum Efficiency Requirements

Equipment Type Size Category Heating Section Type Subcategory or Rating Condition Minimum Efficiency Test Procedurea
Air conditioners, air cooled <65,000 Btu/hb All Split system 13.0 SEER AHRI
210/240
Single package 13.0 SEER
(before 1/20/15)
14 SEER
(as of 1/1/2015)
Through the wall, air cooled ≤30,000 Btu/hb All Split system 12.0 SEER
Single package 12.0 SEER
Small duct high velocity, air cooled <65,000 Btu/hb All Split System 11.0 SEER
Air conditioners, air cooled ≥65,000 Btu/h and <135,000 Btu/h Electric resistance (or none) Split system and single package 11.2 EER
11.4 IEER
(before 1/1/2016)
12.9 IEER
(as of 1/1/2016)
AHRI 340/360
All other Split system and single package 11.0 EER
11.2 IEER
(before 1/1/2016)
12.7 IEER
(as of 1/1/2016)
≥135,000 Btu/h and <240,000 Btu/h Electric resistance (or none) Split system and single package 11.0 EER
11.2 IEER
(before 1/1/2016)
12.4 IEER
(as of 1/1/2016)
All other Split system and single package 10.8 EER
11.0 IEER
(before 1/1/2016)
12.2 IEER
(as of 1/1/2016)
≥240,000 Btu/h and <760,000 Btu/h Electric resistance (or none) Split system and single package 10.0 EER
10.1 IEER
(before 1/1/2016)
11.6 IEER
(as of 1/1/2016)
All other Split system and single package 9.8 EER
9.9 IEER
(before 1/1/2016)
11.4 IEER
(as of 1/1/2016)
≥ 760,000 Btu/h Electric resistance (or none) Split system and single package 9.7 EER
9.8 IEER
(before 1/1/2016)
11.2 IEER
(as of 1/1/2016)
All other Split system and single package 9.5 EER
9.6 IEER
(before 1/1/2016)
11.0 IEER
(as of 1/1/2016)
Air conditioners, water cooled <65,000 Btu/h All Split system and single package 12.1 EER
12.3 IEER
AHRI 210/240
≥65,000 Btu/h and <135,000 Btu/h Electric resistance (or none) Split system and single package 12.1 EER
12.3 IEER
(before 1/1/2016)
13.9 IEER
(as of 1/1/2016)
AHRI 340/360
All other Split system and single package 11.9 EER
12.1 IEER
(before 1/1/2016)
13.7 IEER
(as of 1/1/2016)
≥135,000 Btu/h and <240,000 Btu/h Electric resistance (or none) Split system and single package 12.5 EER
12.5 IEER
(before 1/1/2016)
13.9 IEER
(as of 1/1/2016)
All other Split system and single package 12.3 EER
12.5 IEER
(before 1/1/2016)
13.7 IEER
(as of 1/1/2016)
≥240,000 Btu/h and <760,000 Btu/h Electric resistance (or none) Split system and single package 12.4 EER
12.6 IEER
(before 1/1/2016)
13.6 IEER
(as of 1/1/2016)
AHRI 340/360
All other Split system and single package 12.2 EER
12.4 IEER
(before 1/1/2016)
13.4 IEER
(as of 1/1/2016)
≥760,000 Btu/h Electric resistance (or none) Split system and single package 12.2 EER
12.4 IEER
(before 1/1/2016)
13.5 IEER
(as of 1/1/2016)
AHRI 340/360
All other Split system and single package 12.0 EER
12.2 IEER
(before 1/1/2016)
13.3 IEER
(as of 1/1/2016)
Air conditioners, evaporatively cooled <65,000 Btu/hb All Split system and single package 12.1 EER
12.3 IEER
AHRI 210/ 240
≥65,000 Btu/h and <135,000 Btu/h Electric resistance (or none) Split system and single package 12.1 EER
12.3 IEER
AHRI 340/ 360
All other Split system and single package 11.9 EER
12.1 IEER
≥135,000 Btu/h and <240,000 Btu/h Electric resistance (or none) Split system and single package 12.0 EER
12.2 IERR
All other Split system and single package 11.8 EER
12.0 IEER
≥240,000 Btu/h and <760,000 Btu/h Electric resistance (or none) Split system and single package 11.9 EER
12.1 IEER
All other Split system and single package 11.7 EER
11.9 IEER
≥760,000 Btu/h Electric resistance (or none) Split system and single package 11.7 EER
11.9 IEER
All other Split system and single package 11.5 EER
11.7 IEER
Condensing units, air cooled ≥135,000 Btu/h     10.5 EER
11.8 IEER
AHRI 365
Condensing units, water cooled ≥135,000 Btu/h     13.5 EER
14.0 IEER
Condensing units, evaporatively cooled ≥135,000 Btu/h     13.5 EER
14.0 IEER

a. Section 12 contains a complete specification of the referenced test procedure, including the referenced year version of the test procedure.

b. Single-phase, air-cooled air conditioners <65,000 Btu/h are regulated by NAECA. SEER values are those set by NAECA.

TABLE 6.8.1-2 Electrically Operated Unitary and Applied Heat Pumps—Minimum Efficiency Requirements

Equipment Type Size Category Heating Section Type Subcategory or Rating Condition Minimum Efficiency Test Procedurea
Air cooled (cooling mode) <65,000 Btu/hb All Split system 13.0 SEER
(before 1/1/2015) 14 SEER
(as of 1/1/2015)
AHRI 210/240
Single package 13.0 SEER
(before 1/1/2015) 14 SEER
(as of 1/1/2015)
Through the wall, air cooled (cooling mode) ≤30,000 Btu/hb All Split system 12.0 SEER
Single package 12.0 SEER
Small duct high velocity, air cooled <65,000 Btu/hb All Split System 11.0 SEER
Air cooled (cooling mode) ≥65,000 Btu/h and <135,000 Btu/h Electric resistance (or none) Split system and single package 11.0 EER
11.2 IEER
(before 1/1/2016)
12.2 IEER
(as of 1/1/2016)
AHRI 340/360
All other Split system and single package 10.8 EER
11.0 IEER
(before 1/1/2016)
12.0 IEER
(as of 1/1/2016)
≥135,000 Btu/h and <240,000 Btu/h Electric resistance (or none) Split system and single package 10.6 EER
10.7 IEER
(before 1/1/2016)
11.6 IEER
(as of 1/1/2016)
All other Split system and single package 10.4 EER
10.5 IEER
(before 1/1/2016)
11.4 IEER
(as of 1/1/2016)
≥240,000 Btu/h Electric resistance (or none) Split system and single package 9.5 EER
9.6 IEER
(before 1/1/2016)
10.6 IEER
(as of 1/1/2016)
All other Split system and single package 9.3 EER
9.4 IEER
(before 1/1/2016)
10.4 IEER
(as of 1/1/2016)
Water to air, water loop (cooling mode) <17,000 Btu/h All 86°F entering water 12.2 EER ISO 13256-1
≥17,000 Btu/h and <65,000 Btu/h All 86°F entering water 13.0 EER
≥65,000 Btu/h and <135,000 Btu/h All 86°F entering water 13.0 EER
Water to air, groundwater (cooling mode) <135,000 Btu/h All 59°F entering water 18.0 EER
Brine to air, ground loop (cooling mode) <135,000 Btu/h All 77°F entering water 14.1 EER
Water to water, water loop (cooling mode) <135,000 Btu/h All 86°F entering water 10.6 EER ISO 13256-2
Water to water, groundwater (cooling mode) <135,000 Btu/h All 59°F entering water 16.3 EER
Brine to water, ground loop (cooling mode) <135,000 Btu/h All 77°F entering water 12.1 EER
Air cooled (heating mode) <65,000 Btu/hb (cooling capacity) Split system 7.7 HSPF
(before 1/1/2015) 8.2 HSPF
(as of 1/1/2015)
AHRI 210/240
Single package 7.7 HSPF
(before 1/1/2015) 8.0 HSPF
(as of 1/1/2015)
Through the wall, air cooled (heating mode) ≤30,000 Btu/hb (cooling capacity) Split system 7.4 HSPF
Single package 7.4 HSPF
Small duct high velocity, air cooled (heating mode) <65,000 Btu/hb Split System 6.8 HSPF
Air cooled (heating mode) ≥65,000 Btu/hc and <135,000 Btu/h (cooling capacity) 47°F db/43°F wb outdoor air 3.3 COPH AHRI 340/360
17°F db/15°F wb outdoor air 2.25 COPH
≥135,000 Btu/h°c (cooling capacity) 47°F db/43°F wb outdoor air 3.2 COPH
17°F db/15°F wb outdoor air 2.05 COPH
Water to air, water loop (heating mode) <135,000 Btu/h (cooling capacity) 68°F entering water 4.3 COPH ISO 13256-1
Water to air, groundwater (heating mode) <135,000 Btu/h (cooling capacity) 50°F entering water 3.7 COPH
Brine to air, ground loop (heating mode) <135,000 Btu/h (cooling capacity) 32°F entering water 3.2 COPH
Water to water, water loop (heating mode) <135,000 Btu/h (cooling capacity) 68°F entering water 3.7 COPH ISO 13256-2
Water to water, groundwater (heating mode) <135,000 Btu/h (cooling capacity) 50°F entering water 3.1 COPH
Brine to water, ground loop (heating mode) <135,000 Btu/h (cooling capacity) 32°F entering water 2.5 COPH

a. Section 12 contains a complete specification of the referenced test procedure, including the referenced year version of the test procedure.

b. Single-phase, air-cooled air conditioners <65,000 Btu/h are regulated by NAECA. SEER values are those set by NAECA.

TABLE 6.8.1-3 Water-Chilling Packages—Efficiency Requirementsa,b,e

Equipment Type Size Category Units Effective 1/1/2010 Effective 1/1/2015 Test Procedurec
Path A Path B Path A Path B
Air-cooled chillers <150 tons EER (Btu/Wh) ≥9.562 FL NAd ≥10.100 FL ≥9.700 FL AHRI 550/590
≥12.500 IPLV ≥13.700 IPLV ≥15.800 IPLV
≥150 tons ≥9.562 FL NAd ≥10.100 FL ≥9.700 FL
≥12.750 IPLV ≥14.000 IPLV ≥16.100 IPLV
Air-cooled without condenser, electrically operated All capacities EER (Btu/Wh) Air-cooled chillers without condenser must be rated with matching condensers and comply with air-cooled chiller efficiency requirements
Water-cooled, electrically operated positive displacement <75 tons kW/ton ≤0.780 FL ≤0.800 FL ≤0.750 FL ≤0.780 FL
≤0.630 IPLV ≤0.600 IPLV ≤0.600 IPLV ≤0.500 IPLV
≥75 tons and <150 tons ≤0.775 FL ≤0.790 FL ≤0.720 FL ≤0.750 FL
≤0.615 IPLV ≤0.586 IPLV ≤0.560 IPLV ≤0.490 IPLV
≥150 tons and < 300 tons ≤0.680 FL ≤0.718 FL ≤0.660 FL ≤0.680 FL
≤0.580 IPLV ≤0.540 IPLV ≤0.540 IPLV ≤0.440 IPLV
≥300 tons and < 600 tons ≤0.620 FL ≤0.639 FL ≤0.610 FL ≤0.625 FL
≤0.540 IPLV ≤0.490 IPLV ≤0.520 IPLV ≤0.410 IPLV
≥600 tons ≤0.620 FL ≤0.639 FL ≤0.560 FL ≤0.585 FL
≤0.540 IPLV ≤0.490 IPLV ≤0.500 IPLV ≤0.380 IPLV
Water cooled, electrically operated centrifugal <150 tons kW/ton ≤0.634 FL ≤0.639 FL ≤0.610 FL ≤0.695 FL
≤0.596 IPLV ≤0.450 IPLV ≤0.550 IPLV ≤0.440 IPLV
≥150 tons and <300 tons ≤0.634 FL ≤0.639 FL ≤0.610 FL ≤0.635 FL
≤0.596 IPLV ≤0.450 IPLV ≤0.550 IPLV ≤0.400 IPLV
≥300 tons and <400 tons ≤0.576 FL ≤0.600 FL ≤0.560 FL ≤0.595 FL
≤0.549 IPLV ≤0.400 IPLV ≤0.520 IPLV ≤0.390 IPLV
≥400 tons and <600 tons ≤0.576 FL ≤0.600 FL ≤0.560 FL ≤0.585 FL
≤0.549 IPLV ≤0.400 IPLV ≤0.500 IPLV ≤0.380 IPLV
≥600 tons ≤0.570 FL ≤0.590 FL ≤0.560 FL ≤0.585 FL
≤0.539 IPLV ≤0.400 IPLV ≤0.500 IPLV ≤0.380 IPLV
Air-cooled absorption, single effect All capacities COP (W/W) ≥0.600 FL NAd ≥0.600 FL NAd AHRI 560
Water-cooled absorption, single effect All capacities COP (W/W) ≥0.700 FL NAd ≥0.700 FL NAd
Absorption double effect, indirect fired All capacities COP (W/W) ≥1.000 FL NAd ≥1.000 FL NAd
≥1.050 IPLV ≥1.050 IPLV
Absorption double effect, direct fired All capacities COP (W/W) ≥1.000 FL NAd ≥1.000 FL NAd
≥1.000 IPLV ≥1.000 IPLV

a. The requirements for centrifugal chillers shall be adjusted for nonstandard rating conditions per Section 6.4.1.2.1 and are only applicable for the range of conditions listed there. The requirements for air-cooled, water-cooled positive displacement and absorption chillers are at standard rating conditions defined in the reference test procedure.

b. Both the full-load and IPLV requirements must be met or exceeded to comply with this standard. When there is a Path B, compliance can be with either Path A or Path B for any application.

c. Section 12 contains a complete specification of the referenced test procedure, including the referenced year version of the test procedure.

d. NA means the requirements are not applicable for Path B, and only Path A can be used for compliance.

e. FL is the full-load performance requirements, and IPLV is for the part-load performance requirements.

TABLE 6.8.1-4 Electrically Operated Packaged Terminal Air Conditioners, Packaged Terminal Heat Pumps, Single-Package Vertical Air Conditioners, Single-Package Vertical Heat Pumps, Room Air Conditioners, and Room Air-Conditioner Heat Pumps—Minimum Efficiency Requirements

Equipment Type Size Category (Input) Subcategory or Rating Condition Minimum Efficiency Test Procedurea
PTAC (cooling mode) standard size All capacities 95°F db outdoor air 13.8 — (0.300 × Cap/1000)c
(before 1/1/2015)
14.0 — (0.300 × Cap/1000)c
(as of 1/1/2015)
AHRI 310/ 380
PTAC (cooling mode) nonstandard sizea All capacities 95°F db outdoor air 10.9 — (0.213 × Cap/1000)c EER
PTHP (cooling mode) standard size All capacities 95°F db outdoor air 14.0 — (0.300 × Cap/1000)c
PTHP (cooling mode) nonstandard sizeb All capacities 95°F db outdoor air 10.8 — (0.213 × Cap/1000)c EER
PTHP (heating mode) standard size All capacities 3.7 — (0.052 × Cap/1000)c COPH
PTHP (heating mode) nonstandard sizeb All capacities 2.9 — (0.026 × Cap/1000)c COPH
SPVAC (cooling mode) <65,000 Btu/h 95°F db/75°F wb outdoor air 10.0 EER AHRI 390
≥65,000 Btu/h and <135,000 Btu/h 95°F db/75°F wb outdoor air 10.0 EER
≥135,000 Btu/h and <240,000 Btu/h 95°F db/75°F wb outdoor air 10.0 EER
SPVHP (cooling mode) <65,000 Btu/h 95°F db/75°F wb outdoor air 10.0 EER
≥65,000 Btu/h and <135,000 Btu/h 95°F db/75°F wb outdoor air 10.0 EER
≥135,000 Btu/h and <240,000 Btu/h 95°F db/75°F wb outdoor air 10.0 EER
SPVHP (heating mode) <65,000 Btu/h 47°F db/43°F wb outdoor air 3.0 COPH
≥65,000 Btu/h and <135,000 Btu/h 47°F db/43°F wb outdoor air 3.0 COPH
≥135,000 Btu/h and <240,000 Btu/h 47°F db/43°F wb outdoor air 3.0 COPH
Room air conditioners with louvered sides <6000 Btu/h 9.7 SEER ANSI/AHAM RAC-1
≥6000 Btu/h and <8000 Btu/h 9.7 SEER
≥8000 Btu/h and <14,000 Btu/h 9.8 EER
≥14,000 Btu/h and <20,000 Btu/h 9.7 SEER
≥20,000 Btu/h 8.5 EER
SPVAC (cooling mode), nonweatherized spaceconstrained ≤30,000 Btu/h 95°F db/75°F wb outdoor air 9.2 EER AHRI 390
>30,000 Btu/h and ≤36,000 Btu/h 95°F db/75°F wb outdoor air 9.0 EER
SPVHP (cooling mode), nonweatherized spaceconstrained ≤30,000 Btu/h 95°F db/75°F wb outdoor air 9.2 EER
>30,000 Btu/h and ≤36,000 Btu/h 95°F db/75°F wb outdoor air 9.0 EER
SPVHP (heating mode), nonweatherized spaceconstrained ≤30,000 Btu/h 47°F db/43°F wb outdoor air 3.0 COPH
>30,000 Btu/h and ≤36,000 Btu/h 47°F db/43°F wb outdoor air 3.0 COPH
Room air conditioners without louvered sides <8000 Btu/h 9.0 EER ANSI/AHAM RAC-1
≥8000 Btu/h and <20,000 Btu/h 8.5 EER
≥20,000 Btu/h 8.5 EER
Room air-conditioner heat pumps with louvered sides <20,000 Btu/h 9.0 EER
≥20,000 Btu/h 8.5 EER
Room air-conditioner heat pumps without louvered sides <14,000 Btu/h 8.5 EER
≥14,000 Btu/h 8.0 EER
Room air conditioner, casement only All capacities 8.7 EER
Room air conditioner, casement slider All capacities 9.5 EER

a. Section 12 contains a complete specification of the referenced test procedure, including the referenced year version of the test procedure.

b. Nonstandard size units must be factory labeled as follows: "MANUFACTURED FOR NONSTANDARD SIZE APPLICATIONS ONLY; NOT TO BE INSTALLED IN NEW STANDARD PROJECTS." Nonstandard size efficiencies apply only to units being installed in existing sleeves having an external wall opening of less than 16 in. high or less than 42 in. wide and having a cross-sectional area less than 670 in.2.

c. "Cap" means the rated cooling capacity of the product in Btu/h. If the unit's capacity is less than 7000 Btu/h, use 7000 Btu/h in the calculation. If the unit's capacity is greater than 15,000 Btu/h, use 15,000 Btu/h in the calculation.

TABLE 6.8.1-5 Warm-Air Furnaces and Combination Warm-Air Furnaces/Air-Conditioning Units, Warm-Air Duct Furnaces, and Unit Heaters

Equipment Type Size Category (Input) Subcategory or Rating Condition Minimum Efficiency Test Procedurea
Warm-air furnace, gas fired <225,000 Btu/h Maximum capacityc 78% AFUE or 80% Et b,d DOE 10 CFR Part 430 or Section 2.39, Thermal Efficiency, ANSI Z21.47
≥225,000 Btu/h Maximum capacityc 80% Etd Section 2.39, Thermal Efficiency, ANSI Z21.47
Warm-air furnace, oil fired <225,000 Btu/h Maximum capacityc 78% AFUE or 80% Etb,d DOE 10 CFR Part 430 or Section 42, Combustion, UL 727
≥225,000 Btu/h Maximum capacityc 81% Etd Section 42, Combustion, UL 727
Warm-air duct furnaces, gas fired All capacities Maximum capacityc 80% Ece Section 2.10, Efficiency, ANSI Z83.8
Warm-air unit heaters, gas fired All capacities Maximum capacityc 80% Ece,f Section 2.10, Efficiency, ANSI Z83.8
Warm-air unit heaters, oil fired All capacities Maximum capacityc 80% Ece,f Section 40, Combustion, UL 731

a. Section 12 contains a complete specification of the referenced test procedure, including the referenced year version of the test procedure.

b. Combination units not covered by NAECA (three-phase power or cooling capacity greater than or equal to 65,000 Btu/h) may comply with either rating.

c. Compliance of multiple firing rate units shall be at the maximum firing rate.

d. Et = thermal efficiency. Units must also include an interrupted or intermittent ignition device (IID), have jacket losses not exceeding 0.75% of the input rating, and have either power venting or a flue damper. A vent damper is an acceptable alternative to a flue damper for those furnaces where combustion air is drawn from the conditioned space.

e. Ec = combustion efficiency (100% less flue losses). See test procedure for detailed discussion.

f. As of August 8, 2008, according to the Energy Policy Act of 2005, units must also include an interrupted or intermittent ignition device (IID) and have either power venting or an automatic flue damper.

TABLE 6.8.1-6 Gas- and Oil-Fired Boilers—Minimum Efficiency Requirements

Equipment Typea Subcategory or Rating Condition Size Category (Input) Minimum Efficiency Efficiency as of 3/2/2020 Test Procedure
Boilers, hot water Gas fired <300,000 Btu/hf,g 82% AFUE 82% AFUE 10 CFR Part 430
≥300,000 Btu/h and ≤2,500,000 Btu/hd 80% Et 80% Et 10 CFR Part 431
>2,500,000 Btu/ha 82% Ec 82% Ec
Oil firede <300,000 Btu/hg 84% AFUE 84% AFUE 10 CFR Part 430
≥300,000 Btu/h and ≤2,500,000 Btu/hd 82% Et 82% Et 10 CFR Part 431
>2,500,000 Btu/ha 84% Ec 84% Ec
Boilers, steam Gas fired <300,000 Btu/hf 80% AFUE 80% AFUE 10 CFR Part 430
Gas fired—all, except natural draft ≥300,000 Btu/h and ≤2,500,000 Btu/hd 79% Et 79% Et 10 CFR Part 431
>2,500,000 Btu/ha 79% Et 79% Et
Gas fired— natural draft ≥300,000 Btu/h and ≤2,500,000 Btu/hd 77% Et 79% Et
>2,500,000 Btu/ha 77% Et 79% Et
Oil firede <300,000 Btu/h 82% AFUE 82% AFUE 10 CFR Part 430
≥300,000 Btu/h and ≤2,500,000 Btu/hd 81% Et 81% Et 10 CFR Part 431
>2,500,000 Btu/ha 81% Et 81% Et

a. These requirements apply to boilers with rated input of 8,000,000 Btu/h or less that are not packaged boilers and to all packaged boilers. Minimum efficiency requirements for boilers cover all capacities of packaged boilers.

b. Ec = combustion efficiency (100% less flue losses). See reference document for detailed information.

c. Et = thermal efficiency. See reference document for detailed information.

d. Maximum capacity—minimum and maximum ratings as provided for and allowed by the unit's controls.

e. Includes oil-fired (residual).

f. Boilers shall not be equipped with a constant burning pilot light.

g. A boiler not equipped with a tankless domestic water heating coil shall be equipped with an automatic means for adjusting the temperature of the water such that an incremental change in inferred heat load produces a corresponding incremental change in the temperature of the water supplied.

TABLE 6.8.1-7 Performance Requirements for Heat Rejection Equipment

Equipment Type Total System Heat Rejection Capacity at Rated Conditions Subcategory or Rating Conditionh Performance Requireda,b,c,d,f,g Test Proceduree
Propeller or axial fan open-circuit cooling towers All 95°F entering water
85°F leaving water
75°F entering wb
≥40.2 gpm/hp CTI ATC-105 and CTI STD-201
Centrifugal fan open-circuit cooling towers All 95°F entering water
85°F leaving water
75°F entering wb
≥20.0 gpm/hp CTI ATC-105 and CTI STD-201
Propeller or axial fan closed-circuit cooling towers All 102°F entering water
90°F leaving water
75°F entering wb
≥14.0 gpm/hp CTI ATC-105S and CTI STD-201
Centrifugal closed-circuit cooling towers All 102°F entering water
90°F leaving water
75°F entering wb
≥7.0 gpm/hp CTI ATC-105S and CTI STD-201
Propeller or axial fan evaporative condensers All R-507A test fluid 165°F entering gas temperature 105°F condensing temperature 75°F entering wb ≥157,000 Btu/h•hp CTI ATC-106
Propeller or axial fan evaporative condensers All Ammonia test fluid 140°F entering gas temperature 96.3°F condensing temperature 75°F entering wb ≥134,000 Btu/h•hp CTI ATC-106
Centrifugal fan evaporative condensers All R-507A test fluid 165°F entering gas temperature 105°F condensing temperature 75°F entering wb ≥135,000 Btu/h•hp CTI ATC-106
Centrifugal fan evaporative condensers All Ammonia test fluid 140°F entering gas temperature 96.3°F condensing temperature 75°F entering wb ≥110,000 Btu/h•hp CTI ATC-106
Air cooled condensers All 125°F condensing temperature 190°F entering gas temperature 15°F subcooling 95°F entering db ≥176,000 Btu/h•hp AHRI 460

a. For purposes of this table, open-circuit cooling tower performance is defined as the water flow rating of the tower at the thermal rating condition listed in Table 6.8.1-7 divided by the fan motor nameplate power.

b. For purposes of this table, closed-circuit cooling tower performance is defined as the process water flow rating of the tower at the thermal rating condition listed in Table 6.8.1-7 divided by the sum of the fan motor nameplate power and the integral spray pump motor nameplate power.

c. For purposes of this table, air-cooled condenser performance is defined as the heat rejected from the refrigerant divided by the fan motor nameplate power.

d. Section 12 contains a complete specification of the referenced test procedure, including the referenced year version of the test procedure.

e. The efficiencies and test procedures for both open- and closed-circuit cooling towers are not applicable to hybrid cooling towers that contain a combination of separate wet and dry heat exchange sections. The certification requirements do not apply to field-erected cooling towers.

f. All cooling towers shall comply with the minimum efficiency listed in the table for that specific type of tower with the capacity effect of any project-specific accessories and/or options included in the capacity of the cooling tower.

g. For purposes of this table, evaporative condenser performance is defined as the heat rejected at the specified rating condition in the table, divided by the sum of the fan motor nameplate power and the integral spray pump nameplate power.

h. Requirements for evaporative condensers are listed with ammonia (R-717) and R-507A as test fluids in the table. Evaporative condensers intended for use with halocarbon refrigerants other than R-507A must meet the minimum efficiency requirements listed above with R-507A as the test fluid.

TABLE 6.8.1-8 Heat Transfer Equipment

Equipment Type Subcategory Minimum Efficiencya Test Procedureb
Liquid-to-liquid heat exchangers Plate type NR AHRI 400

a. NR = No requirement

b. Section 12 contains a complete specification of the referenced test procedure, including the referenced year version of the test procedure.

TABLE 6.8.1-9 Electrically Operated Variable-Refrigerant-Flow Air Conditioners— Minimum Efficiency Requirements

Equipment Type Size Category Heating Section Type Subcategory or Rating Condition Minimum Efficiency Test Procedure
VRF multisplit system <65,000 Btu/h All VRF multisplit system 13.0 SEER AHRI 1230
≥65,000 Btu/h and <135,000 Btu/h Electric resistance (or none) VRF multisplit system 11.2 EER
13.1 IEER
≥135,000 Btu/h and <240,000 Btu/h Electric resistance (or none) VRF multisplit system 11.0 EER
12.9 IEER
≥ 240,000 Btu/h Electric resistance (or none) VRF multisplit system 10.0 EER
11.6 IEER

TABLE 6.8.1-10 Electrically Operated Variable-Refrigerant-Flow and Applied Heat Pumps— Minimum Efficiency Requirements

Equipment Type Size Category Heating Section Type Subcategory or Rating Condition Minimum Efficiency Test Procedure
VRF air cooled (cooling mode) <65,000 Btu/h All VRF multisplit system 13.0 SEER AHRI 1230
≥65,000 Btu/h and <135,000 Btu/h Electric resistance (or none) VRF multisplit system 11.0 EER
12.9 IEER
≥65,000 Btu/h and <135,000 Btu/h Electric resistance (or none) VRF multisplit system with heat recovery 10.8 EER 12.7 IEER
≥135,000 Btu/h and <240,000 Btu/h Electric resistance (or none) VRF multisplit system 10.6 EER
12.3 IEER
≥135,000 Btu/h and <240,000 Btu/h Electric resistance (or none) VRF multisplit system with heat recovery 10.4 EER
12.1 IEER
≥240,000 Btu/h Electric resistance (or none) VRF multisplit system 9.5 EER
11.0 IEER
≥240,000 Btu/h Electric resistance (or none) VRF multisplit system with heat recovery 9.3 EER
10.8 IEER
VRF water source (cooling mode) <65,000 Btu/h All VRF multisplit systems 86°F entering water 12.0 EER AHRI 1230
<65,000 Btu/h All VRF multisplit systems with heat recovery 86°F entering water 11.8 EER
≥65,000 Btu/h and <135,000 Btu/h All VRF multisplit system 86°F entering water 12.0 EER
≥65,000 Btu/h and <135,000 Btu/h All VRF multisplit system with heat recovery 86°F entering water 11.8 EER
≥135,000 Btu/h All VRF multisplit system 86°F entering water 10.0 EER
≥135,000 Btu/h All VRF multisplit system with heat recovery 86°F entering water 9.8 EER
VRF groundwater source (cooling mode) <135,000 Btu/h All VRF multisplit system 59°F entering water 16.2 EER AHRI 1230
<135,000 Btu/h All VRF multisplit system with heat recovery 59°F entering water 16.0 EER
≥135,000 Btu/h All VRF multisplit system 59°F entering water 13.8 EER
≥135,000 Btu/h All VRF multisplit system with heat recovery 59°F entering water 13.6 EER
<135,000 Btu/h All VRF multisplit system 77°F entering water 13.4 EER AHRI 1230
<135,000 Btu/h All VRF multisplit system with heat recovery 77°F entering water 13.2 EER
≥135,000 Btu/h All VRF multisplit system 77°F entering water 11.0 EER
≥135,000 Btu/h All VRF multisplit system 77°F entering water 11.0 EER
≥135,000 Btu/h All VRF multisplit system with heat recovery 77°F entering water 10.8 EER
VRF air cooled (heating mode) <65,000 Btu/h (cooling capacity) VRF multisplit system 7.7 HSPF AHRI 1230
≥65,000 Btu/h and <135,000 Btu/h (cooling capacity) VRF multisplit system 47°F db/43°F wb outdoor air 3.3 COPH
17°F db/15°F wb outdoor air 2.25 COPH
≥135,000 Btu/h (cooling capacity) VRF multisplit system 47°F db/43°F wb outdoor air 3.2 COPH
17°F db/15°F wb outdoor air 2.05 COPH
VRF water source (heating mode) <135,000 Btu/h (cooling capacity) VRF multisplit system 68°F entering water 4.2 COPH AHRI 1230
≥135,000 Btu/h (cooling capacity) VRF multisplit system 68°F entering water 3.9 COPH
VRF groundwater source (heating mode) <135,000 Btu/h (cooling capacity) VRF multisplit system 50°F entering water 3.6 COPH AHRI 1230
≥135,000 Btu/h (cooling capacity) VRF multisplit system 50°F entering water 3.3 COPH
VRF ground source (heating mode) <135,000 Btu/h (cooling capacity) VRF multisplit system 32°F entering water 3.1 COPH AHRI 1230
≥135,000 Btu/h (cooling capacity) VRF multisplit system 32°F entering water 2.8 COPH

TABLE 6.8.1-11 Air Conditioners and Condensing Units Serving Computer Rooms

Equipment Type Net Sensible Cooling Capacitya Minimum SCOP-127b Efficiency Downflow Units/Upflow Units Test Procedure
Air conditioners, air cooled <65,000 Btu/h 2.20/2.09 ANSI/ASHRAE 127
≥ 65,000 Btu/h and < 240,000 Btu/h 2.10/1.99
≥ 240,000 Btu/h 1.90/1.79
Air conditioners, water cooled <65,000 Btu/h 2.60/2.49 ANSI/ASHRAE 127
≥ 65,000 Btu/h and < 240,000 Btu/h 2.50/2.39
≥ 240,000 Btu/h 2.40/2.29
Air conditioners, water cooled with fluid economizer <65,000 Btu/h 2.55/2.44 ANSI/ASHRAE 127
≥ 65,000 Btu/h and < 240,000 Btu/h 2.45/2.34
≥ 240,000 Btu/h 2.35/2.24
Air conditioners, glycol cooled (rated at 40% propylene glycol) <65,000 Btu/h 2.50/2.39 ANSI/ASHRAE 127
≥ 65,000 Btu/h and < 240,000 Btu/h 2.15/2.04
≥ 240,000 Btu/h 2.10/1.99
Air conditioners, glycol cooled (rated at 40% propylene glycol) with fluid economizer <65,000 Btu/h 2.45/2.34 ANSI/ASHRAE 127
≥ 65,000 Btu/h and < 240,000 Btu/h 2.10/1.99
≥ 240,000 Btu/h 2.05/1.94

a. Net sensible cooling capacity: The total gross cooling capacity less the latent cooling less the energy to the air movement system. (Total Gross — Latent — Fan Power)

b. Sensible coefficient of performance (SCOP-127): A ratio calculated by dividing the net sensible cooling capacity in watts by the total power input in watts (excluding reheaters and humidifiers) at conditions defined in ASHRAE Standard 127. The net sensible cooling capacity is the gross sensible capacity minus the energy dissipated into the cooled space by the fan system.

TABLE 6.8.1-12 Commercial Refrigerator and Freezers

Equipment Type Application Energy Use Limits, kWh/day Test Procedure
Refrigerator with solid doors   0.10 × V + 2.04 AHRI 1200
Refrigerator with transparent doors   0.12 × V + 3.34
Freezers with solid doors Holding temperature 0.40 × V + 1.38
Freezers with transparent doors   0.75 × V + 4.10
Refrigerators/freezers with solid doors   the greater of 0.12 × V + 3.34 or 0.70
Commercial refrigerators Pulldown 0.126 × V + 3.51  

V = the chiller or frozen compartment volume (ft3) as defined in Association of Home Appliance Manufacturers Standard HRF-1.

TABLE 6.8.1-13 Commercial Refrigeration—Minimum Efficiency Requirements

Equipment Type Energy Use Limits as of 1/1/2012,b,c kWh/day Test Procedure
Equipment Classa Family Code Operating Mode Rating Temperature
VOP.RC.M Vertical open Remote condensing Medium temperature 0.82 ×TDA+4.07 AHRI 1200
SVO.RC.M Semivertical open Remote condensing Medium temperature 0.83 ×TDA+3.18
HZO.RC.M Horizontal open Remote condensing Medium temperature 0.35 ×TDA+2.88
VOP.RC.L Vertical open Remote condensing Low temperature 2.27 ×TDA+6.85
HZO.RC.L Horizontal open Remote condensing Low temperature 0.57 ×TDA+6.88
VCT.RC.M Vertical transparent door Remote condensing Medium temperature 0.22 ×TDA+1.95
VCT.RC.L Vertical transparent door Remote condensing Low temperature 0.56 ×TDA+2.61
SOC.RC.M Service over counter Remote condensing Medium temperature 0.51 ×TDA+0.11
VOP.SC.M Vertical open Self contained Medium temperature 1.74 ×TDA+4.71
SVO.SC.M Semivertical open Self contained Medium temperature 1.73 ×TDA+4.59
HZO.SC.M Horizontal open Self contained Medium temperature 0.77 ×TDA+5.55
HZO.SC.L Horizontal open Self contained Low temperature 1.92 ×TDA+7.08
VCT.SC.I Vertical transparent door Self contained Ice cream 0.67 ×TDA+3.29
VCS.SC.I Vertical solid door Self contained Ice cream 0.38 × V+0.88
HCT.SC.I Horizontal transparent door Self contained Ice cream 0.56 ×TDA+0.43
SVO.RC.L Semivertical open Remote condensing Low temperature 2.27 ×TDA+6.85
VOP.RC.I Vertical open Remote condensing Ice cream 2.89 ×TDA+8.7
SVO.RC.I Semivertical open Remote condensing Ice cream 2.89 ×TDA+8.7
HZO.RC.I Horizontal open Remote condensing Ice cream 0.72 ×TDA+8.74
VCT.RC.I Vertical transparent door Remote condensing Ice cream 0.66 ×TDA+3.05
HCT.RC.M Horizontal transparent door Remote condensing Medium temperature 0.16 ×TDA+0.13
HCT.RC.L Horizontal transparent door Remote condensing Low temperature 0.34 ×TDA+0.26
HCT.RC.I Horizontal transparent door Remote condensing Ice cream 0.4 ×TDA+0.31
VCS.RC.M Vertical solid door Remote condensing Medium temperature 0.11 × V+0.26
VCS.RC.L Vertical solid door Remote condensing Low temperature 0.23 × V+0.54
VCS.RC.I Vertical solid door Remote condensing Ice cream 0.27 × V+0.63
HCS.RC.M Horizontal solid door Remote condensing Medium temperature 0.11 × V+0.26
HCS.RC.L Horizontal solid door Remote condensing Low temperature 0.23 × V+0.54
HCS.RC.I Horizontal solid door Remote condensing Ice cream 0.27 × V+0.63
HCS.RC.I Horizontal solid door Remote condensing Ice cream 0.27 × V+0.63
SOC.RC.L Service over counter Remote condensing Low temperature 1.08 ×TDA+0.22
SOC.RC.I Service over counter Remote condensing Ice cream 1.26 ×TDA+0.26
VOP.SC.L Vertical open Self contained Low temperature 4.37 ×TDA+11.82
VOP.SC.I Vertical open Self contained Ice cream 5.55 ×TDA+15.02
SVO.SC.L Semivertical open Self contained Low temperature 4.34 ×TDA+11.51
SVO.SC.I Semivertical open Self contained Ice cream 5.52 ×TDA+14.63
HZO.SC.I Horizontal open Self contained Ice cream 2.44 ×TDA+9.0
SOC.SC.I Service over counter Self contained Ice cream 1.76 ×TDA+0.36
HCS.SC.I Horizontal solid door Self contained Ice cream 0.38 × V+0.88

a. Equipment class designations consist of a combination (in sequential order separated by periods (AAA).(BB).(C)) of the following:
(AAA)—An equipment family code (VOP = vertical open, SVO = semivertical open, HZO = horizontal open, VCT = vertical transparent doors, VCS = vertical solid doors, HCT = horizontal transparent doors, HCS = horizontal solid doors, and SOC = service over counter); (BB)—An operating mode code (RC = remote condensing and SC = self contained); and (C)—A rating temperature code (M = medium temperature [38°F], L = low temperature [0°F], or I = ice cream temperature [15°F]). For example, "VOP.RC.M" refers to the "vertical open, remote condensing, medium temperature" equipment class.

b. V is the volume of the case (ft) as measured in AHRI Standard 1200, Appendix C.

c. TDA is the total display area of the case (ft) as measured in AHRI Standard 1200, Appendix D.

TABLE 6.8.2-1 Minimum Duct Insulation R-Value,a Cooling- and Heating-Only Supply Ducts and Return Ducts

Climate Zone Duct Location
Exterior Ventilated Attic Unvented Attic Above Insulated Ceiling Unvented Attic with Roof Insulationa Unconditioned Spaceb Indirectly Conditioned Spacec Buried
Heating-Only Ducts
1, 2 None None None None None None None
3 R-3.5 None None None None None None
4 R-3.5 None None None None None None
5 R-6 R-3.5 None None None None R-3.5
6 R-6 R-6 R-3.5 None None None R-3.5
7 R-8 R-6 R-6 None R-3.5 None R-3.5
8 R-8 R-8 R-6 None R-6 None R-6
Cooling-Only Ducts
1 R-6 R-6 R-8 R-3.5 R-3.5 None R-3.5
2 R-6 R-6 R-6 R-3.5 R-3.5 None R-3.5
3 R-6 R-6 R-6 R-3.5 R-1.9 None None
4 R-3.5 R-3.5 R-6 R-1.9 R-1.9 None None
5, 6 R-3.5 R-1.9 R-3.5 R-1.9 R-1.9 None None
7, 8 R-1.9 R-1.9 R-1.9 R-1.9 R-1.9 None None
Return Ducts
1 to 8 R-3.5 R-3.5 R-3.5 None None None None

a. Insulation R-values, measured in (h•ft2•°F)/Btu, are for the insulation as installed and do not include film resistance. The required minimum thicknesses do not consider water vapor transmission and possible surface condensation. Where exterior walls are used as plenum walls, wall insulation shall be as required by the most restrictive condition of Section 6.4.4.2 or Section 5. Insulation resistance measured on a horizontal plane in accordance with ASTM C518 at a mean temperature of 75°F at the installed thickness.

b. Includes crawlspaces, both ventilated and nonventilated.

c. Includes return air plenums with or without exposed roofs above.

TABLE 6.8.2-2 Minimum Duct Insulation R-Value,a Combined Heating and Cooling Supply Ducts and Return Ducts

Climate Zone Duct Location
Exterior Ventilated Attic Unvented Attic Above Insulated Ceiling Unvented Attic with Roof Insulationa Unconditioned Spaceb Indirectly Conditioned Spacec Buried
Supply Ducts
1 R-6 R-6 R-8 R-3.5 R-3.5 None R-3.5
2 R-6 R-6 R-6 R-3.5 R-3.5 None R-3.5
3 R-6 R-6 R-6 R-3.5 R-3.5 None R-3.5
4 R-6 R-6 R-6 R-3.5 R-3.5 None R-3.5
5 R-6 R-6 R-6 R-1.9 R-3.5 None R-3.5
6 R-8 R-6 R-6 R-1.9 R-3.5 None R-3.5
7 R-8 R-6 R-6 R-1.9 R-3.5 None R-3.5
8 R-8 R-8 R-8 R-1.9 R-6 None R-6
Return Ducts
1 to 8 R-3.5 R-3.5 R-3.5 None None None None

a. Insulation R-values, measured in (h•ft2•°F)/Btu, are for the insulation as installed and do not include film resistance. The required minimum thicknesses do not consider water vapor transmission and possible surface condensation. Where exterior walls are used as plenum walls, wall insulation shall be as required by the most restrictive condition of Section 6.4.4.2 or Section 5. Insulation resistance measured on a horizontal plane in accordance with ASTM C518 at a mean temperature of 75°F at the installed thickness.

b. Includes crawlspaces, both ventilated and nonventilated.

c. Includes return air plenums with or without exposed roofs above.

TABLE 6.8.3-1 Minimum Piping Insulation Thickness Heating and Hot Water Systemsa,b,c,d,e
(Steam, Steam Condensate, Hot Water Heating and Domestic Water Systems)

Fluid Operating Temperature Range(°F) and Usage Insulation Conductivity ≥Nominal Pipe or Tube Size, in.
Conductivity, Btu•in./(h•ft2•°F) Mean Rating Temperature, °F <1 1 to <1-1/2 1-1/2 to <4 4 to <8 ≥8
  Insulation Thickness, in.
>350°F 0.32—0.34 250 4.5 5.0 5.0 5.0 5.0
251°F—350°F 0.29—0.32 200 3.0 4.0 4.5 4.5 4.5
201°F—250°F 0.27—0.30 150 2.5 2.5 2.5 3.0 3.0
141°F—200°F 0.25—0.29 125 1.5 1.5 2.0 2.0 2.0
105°F—140°F 0.22—0.28 100 1.0 1.0 1.5 1.5 1.5

a. For insulation outside the stated conductivity range, the minimum thickness (T) shall be determined as follows: T = r{(1 + t/r)K/k — 1},where T = minimum insulation thickness (in.), r = actual outside radius of pipe (in.), t = insulation thickness listed in this table for applicable fluid temperature and pipe size, K = conductivity of alternate material at mean rating temperature indicated for the applicable fluid temperature (Btu•in./h•ft2•°F); and k = the upper value of the conductivity range listed in this table for the applicable fluid temperature.

b. These thicknesses are based on energy efficiency considerations only. Additional insulation is sometimes required relative to safety issues/surface temperature.

c. For piping smaller than 1.5 in. and located in partitions within conditioned spaces, reduction of these thicknesses by 1 in. shall be permitted (before thickness adjustment required in footnote [a]) but not to thicknesses below 1 in.

d. For direct-buried heating and hot-water system piping, reduction of these thicknesses by 1.5 in. shall be permitted (before thickness adjustment required in footnote [a]) but not to thicknesses below 1 in.

e. The table is based on steel pipe. Nonmetallic pipes schedule 80 thickness or less shall use the table values. For other nonmetallic pipes having thermal resistance greater than that of steel pipe, reduced insulation thicknesses are permitted if documentation is provided showing that the pipe with the proposed insulation has no more heat transfer per metre than a steel pipe of the same size with the insulation thickness shown in the table.

TABLE 6.8.3-2 Minimum Piping Insulation Thickness Cooling Systems (Chilled Water, Brine, and Refrigerant)a,b,c,d

Fluid Operating Temperature Range (°F) and Usage Insulation Conductivity Nominal Pipe or Tube Size, in.
Conductivity, Btu•in./(h•ft2°F) Mean Rating Temperature, °F <1 1 to <1-1/2 1-1/2 to <4 4 to <8 ≥8
Insulation Thickness, in.
40°F—60°F 0.21—0.27 75 0.5 0.5 1.0 1.0 1.0
<40°F 0.20—0.26 50 0.5 1.0 1.0 1.0 1.5

a. For insulation outside the stated conductivity range, the minimum thickness (T) shall be determined as follows: T = r{(1 + t/r)K/k — 1}, where T = minimum insulation thickness (in.), r = actual outside radius of pipe (in.), t = insulation thickness listed in this table for applicable fluid temperature and pipe size, K = conductivity of alternate material at mean rating temperature indicated for the applicable fluid temperature (Btu•in./h•ft2•°F); and k = the upper value of the conductivity range listed in this table for the applicable fluid temperature.

b. These thicknesses are based on energy efficiency considerations only. Issues such as water vapor permeability or surface condensation sometimes require vapor retarders or additional insulation.

c. For direct-buried cooling system piping, insulation is not required.

d. The table is based on steel pipe. Nonmetallic pipes schedule 80 thickness or less shall use the table values. For other nonmetallic pipes having thermal resistance greater than that of steel pipe, reduced insulation thicknesses are permitted if documentation is provided showing that the pipe with the proposed insulation has no more heat transfer per foot than a steel pipe of the same size with the insulation thickness shown in the table.

 

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