6 Heating, Ventilating, and Air Conditioning

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.

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.

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.

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

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.

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.

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.

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

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.

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.

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.

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 and for air curtains with integral heating shall include automatic controls configured to shut off the heating system when outdoor air temperatures are above 45°F (7°C). Vestibule heating and cooling systems shall be controlled by a thermostat in the vestibule that limits heating to a maximum of 60°F (16°C) and cooling to a minimum of 85°F (29°C).

Direct digital control shall be required as follows.

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.

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.

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.

1. Zones for which the volume of air that is reheated, recooled, or mixed is less than the larger of the following:
   1. 20% of the zone design peak supply for systems with DDC and 30%  for other systems
   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

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.

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.

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.

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

	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

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)

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

Device	Adjustment
Credits
Return or exhaust systems required by code or accreditation standards to be fully ducted, or systems required to maintain air pressure differentials between adjacent rooms.	0.5 in. wc (125 Pa) (2.15 in. wc [535 Pa] 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	For each airstream [(2.2 × Energy Recovery Effectiveness) — 0.5] in. wc
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

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.

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 where total design exhaust airflow is more than 70%

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.

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.

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.

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

Chilled- and hot-water distribution systems that include three (3) or more 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 no more than the larger of 25% of the design flow rate or the minimum flow required by the heating/ cooling equipment manufacturer for the proper operation of equipment. Individual chilled water pumps serving variable flow systems having motors exceeding 5 hp (3.7 kW) 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 controls are used the setpoint shall be reset downward based on valve positions until one valve is nearly wide open.

Chilled- and hot-water systems with a design capacity exceeding 300,000 Btu/h (90kW) supplying chilled or heated water 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. Where DDC is used to control valves, the setpoint shall be reset based on valve positions until one valve is nearly wide open or setpoint limits of the system equipment or application have been reached.

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.

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

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.

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.

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.

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

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

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

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.

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

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.

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.

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.

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.

HVAC control systems shall be tested to ensure that control elements are calibrated, adjusted, and in proper working condition. For projects larger than 50,000 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.