5.6 HVAC Zone Level Systems

This group of building descriptors relate to HVAC systems at the zone level. There is not a one-to-one relationship between HVAC components in the proposed design and the standard design since the standard design system is determined from building type, size, and heating source. The applicability of each building descriptor for each of the 11 standard design systems is indicated in tables under the building descriptor standard design rules. Additions and alterations should follow the same requirements stated for new construction proposed designs and new construction standard designs; unless otherwise noted in the descriptor.

5.6.1 Space Temperature Control

Space Thermostat Throttling Range
Applicability	All thermal zones
Definition	The number of degrees that the room temperature must change to cause the HVAC system to go from no heating or cooling (i.e., space temperatures floating) to full heating or cooling
Units	Degrees Fahrenheit (°F)
Input Restrictions	The prescribed value is 2°F. (This is equivalent to a +/- 1°F temperature tolerance around the heating and cooling setpoint.) No input is needed and the prescribed value may not be overridden.
Standard Design	Same as the proposed design
Standard Design: Existing Buildings

Space Temperature Schedule
Applicability	All thermal zones
Definition	An hourly space thermostat schedule
Units	Data structure: temperature schedule
Input Restrictions	Prescribed The schedule group is specified for the given space type in Appendix 5.4A, and the schedule values are specified in Appendix 5.4B.
Standard Design	Schedules in the standard design shall be identical to the proposed design, unless operable windows are present in the thermal zone. For nonresidential spaces, if operable windows are present in the proposed design, the heating schedule shall be overridden to 50°F and the cooling schedule shall be overridden to 90°F whenever the operable window schedule for that hour indicates that the window(s) are open.
Standard Design: Existing Buildings

5.6.2 Terminal Device Data

Terminal Type
Applicability	All thermal zones
Definition	A terminal unit includes any device serving a zone (or group of zones collected in a thermal zone) that has the ability to re-heat or re-cool in response to the zone thermostat. This includes: • None (the case for single zone units) • VAV box • Series fan-powered VAV box • Parallel fan-powered VAV box • Dual-duct mixing box (constant volume and VAV)
Units	List (see above)
Input Restrictions	As designed
Standard Design	Only applicable for multiple zone systems 5 (packaged VAV) and 6 (built-up VAV). See Section 5.1.2 for a summary of the HVAC mapping. For healthcare facilities, same as the Proposed Design.
Standard Design: Existing Buildings	Same as proposed design for unaltered components; same as new construction rules for new secondary systems or terminal units.

5.6.3 Terminal Heating

This group of building descriptors applies to proposed design systems that have reheat coils at the zone level. The building descriptors are applicable for standard design systems 5 and 6.

Terminal Heat Type
Applicability	Systems that have reheat coils at the zone level
Definition	The heating source for the terminal unit. This includes: • Electric resistance • Gas furnace • Oil furnace • Hot water • Steam
Units	List (see above)
Input Restrictions	As designed
Standard Design	Hot water for terminal units with reheat coils For healthcare facilities, same as the Proposed Design.
Standard Design: Existing Buildings

Terminal Heat Capacity
Applicability	Systems that have reheat coils at the zone level
Definition	The heating capacity of the terminal heating source
Units	Btu/h
Input Restrictions	As designed If the unmet load hours exceed 150, the energy analyst and design team may have to increase the size of the equipment so that the unmet load hours are less than 150.
Standard Design	The software shall automatically size the terminal heating capacity to be 25 percent greater than the design loads.
Standard Design: Existing Buildings

Reheat Delta T (^∆Treheat)

Applicability

Systems that have reheat coils at the zone level

Definition

This is an alternate method to enter the terminal heat capacity, which can be calculated as follows:

∆T_reheat=T_reheat-T_(cool_supply)

∆T_reheat=Q_coil⁄(1.1×CFM)

Where:

^∆Treheat	Heat rise across the terminal unit heating coil F)
^Treheat	Heating air temperature at design (F)
^Tcool_supply	Supply air temperature at the heating coil (F)
Q_coil	Heating coil load (Btu/h)
CFM	Airflow (ft³/min)

Units

Degrees Fahrenheit (°F)

Input Restrictions

As designed but may need to be increased if zone unmet load hours are greater than 150

Standard Design

Method not used for standard design. The temperature difference shall be no more than 40°F. See heat capacity.

Standard Design:

Existing Buildings

5.6.4 Baseboard Heat

Baseboard Capacity
Applicability	All thermal zones
Definition	Total heating capacity of the baseboard unit(s)
Units	Btu/h
Input Restrictions	As designed
Standard Design	Not applicable
Standard Design: Existing Buildings

Baseboard Heat Control
Applicability	All thermal zones with baseboard heating
Definition	Defines the control scheme of base board heating as controlled by a space thermostat
Units	List (fixed as By Space Thermostat)
Input Restrictions	Controlled by space thermostat is the only type allowed if baseboard heating is used.
Standard Design	Not applicable
Standard Design: Existing Buildings

Baseboard Heat Source
Applicability	All thermal zones with furnaces or baseboard heating at the zone
Definition	Heating source
Units	List • Electric heat • Gas furnace • Hot water
Input Restrictions
Standard Design	Not applicable, except for healthcare facilities, same as the Proposed Design.
Standard Design: Existing Buildings

5.6.5 VRF Zone Systems (Indoor Units)

The following inputs are required when zone systems are connected to a VRF system (condensing unit).

Acceptance Test Required
Applicability	VRF
Definition	Flag if acceptance test is required
Units	Boolean
Input Restrictions	None
Standard Design	Not applicable

VRF Zone System Type
Applicability	VRF
Definition	Type of zone system
Units	VRF
Input Restrictions	VRF
Standard Design	Not applicable

Count
Applicability	VRF
Definition	The number of duplicate systems represented by the current system. All system attributes must be identical for multiple system assignment.
Units	None
Input Restrictions	None
Standard Design	Not applicable

Indoor Unit Type
Applicability	VRF
Definition	Ducted or Unducted
Units	List – Ducted, Unducted
Input Restrictions	None
Standard Design	Not applicable

Design Supply Air Temperature (Cooling)
Applicability	VRF
Definition	Design SAT in cooling for the zone
Units	Deg F
Input Restrictions	As Designed
Standard Design	Not applicable

Design Supply Air Temperature (Heating)
Applicability	VRF
Definition	Design SAT in heating for the zone
Units	Deg F
Input Restrictions	As Designed
Standard Design	Not applicable

Net Cooling Capacity
Applicability	VRF
Definition	Net cooling capacity of the zone system (one system if count>1), which includes all cooling to the zone but excludes any fan motor heat
Units	Btu/h
Input Restrictions	None
Standard Design	Not applicable

Net Heating Capacity
Applicability	VRF
Definition	Net heating capacity of the zone system (one system if count>1), ), which includes all cooling to the zone but excludes any fan motor heat
Units	Btu/h
Input Restrictions	None
Standard Design	Not applicable

Supply Fan Capacity for Cooling
Applicability	VRF
Definition	The supply fan flow rate when the zone requires cooling
Units	cfm (for each mode)
Input Restrictions	None
Standard Design	Not applicable

Supply Fan Capacity for Heating
Applicability	VRF
Definition	The supply fan flow rate
Units	cfm (for each mode)
Input Restrictions	None
Standard Design	Not applicable

Supply Fan Capacity for Deadband
Applicability	VRF
Definition	Identify the supply fan airflow rate in deadband (floating) mode
Units	cfm (for each mode)
Input Restrictions	None
Standard Design	Not applicable

Supply Temp Control
Applicability	VRF
Definition	The method of controlling the system supply air temperature
Units	List (Constant, reset by outside air, reset by demand)
Input Restrictions	No Supply Air Temperature Control
Standard Design	Not applicable

Auxiliary Power When On
Applicability	VRF
Definition	The parasitic electrical energy use of the zone terminal unit when either terminal unit coil is operating
Units	Watts or Btu/h
Input Restrictions	None
Standard Design	Not applicable

Auxiliary Power When Off
Applicability	VRF
Definition	The parasitic electrical energy use of the zone terminal unit when the terminal unit coils are off
Units	Watts or Btu/h
Input Restrictions	None
Standard Design	Not applicable

5.6.6 Zone Level Air Flow

5.6.6.1 VAV Air Flow

This group of building descriptors applies to proposed design systems that vary the volume of air at the zone level. The building descriptors are applicable for standard design systems 5 and 6.

Design Airflow
Applicability	Systems that vary the volume of air at the zone level
Definition	The air delivery rate at design conditions
Units	Cfm
Input Restrictions	As designed If the unmet load hours in the proposed design are greater than 150, the user may have to modify the design airflow value manually.
Standard Design	For systems 5 and 6, the software shall automatically size the system airflow to meet both: a) The standard design peak cooling load based on a supply-air-to-room-air temperature difference of 20°F for exterior zones or 15°F for interior zones, the required ventilation air from Table 120.1-A of the standards, or makeup air, whichever is greater. b) The standard design peak heating load based on 50 percent zone flow and 95°F supply air temperature. An exterior zone is defined as a type of thermal zone that has any exterior walls, and that has a non-zero amount of vertical fenestration (windows). Any zone that does not meet the definition of an exterior zone is an interior zone. For kitchen MAU systems, the design airflow is the greater of the airflow required to meet the design cooling loads and the total exhaust cfm.
Standard Design: Existing Buildings

Terminal Minimum Stop
Applicability	Systems that vary the volume of air at the zone level
Definition	The minimum airflow that will be delivered by a terminal unit before reheating occurs
Units	Unitless fraction of airflow (cfm) or specific airflow (cfm/ft²)
Input Restrictions	Input must be greater than or equal to the outside air ventilation rate
Standard Design	For systems 5 and 6, packaged VAV units and built-up VAV air handling units, set the minimum airflow to be the greater of 20 percent of the peak supply air volume to the zone or the minimum outside air ventilation rate. For laboratories, the minimum airflow fraction shall be fixed at a value equivalent to the greater of the proposed design minimum exhaust requirements or the minimum ventilation rate.
Standard Design: Existing Buildings

Terminal Heating Control Type
Applicability	VAV boxes with reheat
Definition	The control strategy for the heating mode. Single Maximum: In the single maximum control mode, the airflow is set to a minimum constant value in both the deadband and heating mode. This airflow can vary but is typically 30 to 50 percent of maximum. This control mode typically has a higher minimum airflow than the minimum used in the dual maximum below, resulting in more frequent reheat. Figure 9: Single Maximum VAV Box Control Source: Taylor Engineering Dual Maximum: Raises the supply air temperature (SAT) as the first stage of heating, and increases the airflow to the zone as the second stage of heating. 1. The first stage of heating consists of modulating the zone supply air temperature setpoint up to a maximum setpoint no larger than 95°F while the airflow is maintained at the dead band flow rate. 2. The second stage of heating consists of modulating the airflow rate from the dead band flow rate up to the heating maximum flow rate (50 percent of design flow rate). Figure 10: Dual Maximum Control Sequence Source: Taylor Engineering
Units	List: • Single maximum • Dual maximum
Input Restrictions	Fixed at single maximum if control system type is not direct digital control (DDC) control to the zone level
Standard Design	Dual maximum For healthcare facilities, same as the Proposed Design.
Standard Design: Existing Buildings

5.6.6.2 Fan Powered Boxes

Fan Powered Box Type
Applicability	Thermal zones that have fan powered boxes
Definition	Defines the type of fan-powered induction box
Units	List : • series • parallel
Input Restrictions	As designed
Standard Design	Not applicable For healthcare facilities, same as the Proposed Design.
Standard Design: Existing Buildings

Terminal Fan Power
Applicability	Thermal zones that have fan powered boxes
Definition	Rated power input of the fan in a fan-powered box
Units	W/cfm
Input Restrictions	As designed
Standard Design	Not applicable For healthcare facilities, same as the Proposed Design.
Standard Design: Existing Buildings

Fan Powered Box Induced Air Zone
Applicability	Thermal zones that have fan powered boxes
Definition	Zone from which a series or parallel fan-powered box draws its air
Units	List (of zones)
Input Restrictions	As designed
Standard Design	Not applicable For healthcare facilities, same as the Proposed Design.
Standard Design: Existing Buildings

Parallel PIU Induction Ratio
Applicability	Thermal zones that have fan-powered boxes
Definition	Ratio of induction-side airflow of a fan-powered box at design heating conditions to the primary airflow
Units	Ratio
Input Restrictions	As designed
Standard Design	Not applicable For healthcare facilities, same as the Proposed Design.
Standard Design: Existing Buildings

Parallel Fan Box Thermostat Setpoint
Applicability	Thermal zones that have fan powered boxes
Definition	Temperature difference above the heating setpoint at which the parallel fan is turned on
Units	Degrees Fahrenheit (°F)
Input Restrictions	2°F above the heating setpoint schedule
Standard Design	Not applicable For healthcare facilities, same as the Proposed Design.
Standard Design: Existing Buildings

5.6.6.3 Zone Exhaust

This group of building descriptors describes the rate of exhaust and the schedule or control for this exhaust. An exhaust system can serve one thermal zone or multiple thermal zones. Energy is summed for the exhaust system level, not the thermal zone level.

This section also contains unique inputs for kitchen exhaust systems that must meet requirements of section 140.9 of the Standards.

Kitchen Exhaust Hood Length
Applicability	Exhaust fans in spaces of type kitchen, commercial food preparation
Definition	The exhaust hood length
Units	ft
Input Restrictions	As designed
Standard Design	Same as the proposed design
Standard Design: Existing Buildings

Kitchen Exhaust Hood Style
Applicability	Exhaust fans in spaces of type kitchen, commercial food preparation
Definition	The hood style as defined in Table 140.9-A of the standards
Units	List: • Wall-mounted canopy • Single island • Double island • Eyebrow • Backshelf/Passover
Input Restrictions	As designed
Standard Design	Same as the proposed design
Standard Design: Existing Buildings

Kitchen Exhaust Hood Cooking Duty
Applicability	Exhaust fans in spaces of type kitchen, commercial food preparation
Definition	The hood cooking duty as defined in Table 140.9-A of the standards
Units	List: • Light-duty • Medium-duty • Heavy-duty • Extra heavy-duty
Input Restrictions	As designed
Standard Design	Same as the proposed design
Standard Design: Existing Buildings

Exhaust Fan Name
Applicability	All thermal zones
Definition	A reference to an exhaust fan system that serves the thermal zone
Units	Text or other unique reference to an exhaust fan system defined in the secondary systems section
Input Restrictions	As designed
Standard Design	Same as the proposed design
Standard Design: Existing Buildings

Exhaust Air Flow Rate
Applicability	All thermal zones
Definition	Rate of exhaust from a thermal zone
Units	cfm
Input Restrictions	For nonresidential and hotel/motel spaces, Proposed exhaust air flow rate must meet the minimum exhaust requirements of section 120.1(c)4 for applicable spaces in Table 120.1-B. For laboratory spaces and zones, the design exhaust air flow rate is specified by the user, but a warning shall be posted if less than 1 cfm/ft².
Standard Design	Same as the proposed design but not above the maximum of the standard design ventilation rates listed in Appendix 5.4A and required exhaust ventilation rates from Standards Table 120.1-B for spaces that do not include covered processes. Exception for buildings with over 5,000 cfm of kitchen exhaust; the standard design is a function of the kitchen exhaust hood length, kitchen exhaust hood style, and kitchen exhaust hood cooking duty, and is determined by Title 24 standards, Table 140.9-A. For lab exhaust systems, the standard design is the same as the proposed. For healthcare facilities, same as the Proposed Design.
Standard Design: Existing Buildings

Exhaust Minimum Air Flow Rate
Applicability	All laboratory zones
Definition	Minimum rate of exhaust from a zone
Units	cfm/ft²
Input Restrictions	As designed for non-process zones. For laboratory zones, the exhaust air flow rate is the maximum of the hood scheduled exhaust air flow rate and the minimum ventilation rate. A warning is posted if the minimum exhaust rate is 2 ACH or less.
Standard Design	For laboratory systems with minimum exhaust flow rates exceeding 10 ACH exhaust, the exhaust minimum air flow rate is equal to the proposed design minimum. For VAV laboratory systems with variable flow and variable speed drive exhaust fan control, the exhaust minimum air flow rate is the greater of the proposed design minimum exhaust air flow rate and 20% of the design exhaust air flow rate. For healthcare facilities, same as the Proposed Design.
Standard Design: Existing Buildings

Exhaust Fan Schedule
Applicability	All thermal zones
Definition	Schedule indicating the pattern of use for exhaust air from the thermal zone
Units	Data structure: schedule, fraction
Input Restrictions	For non-process spaces, schedule is prescribed based on occupancy type and specified in Appendix 5.4B. Exhaust fans for non-process loads shall be modeled as constant volume and always on. Exhaust schedules for kitchen exhaust hoods are prescribed and specified in Appendix 5.4B, and dependent on whether the exhaust is constant or variable volume. Exhaust schedules for laboratory spaces are prescribed and specified in Appendix 5.4B, and dependent on whether the exhaust is constant or variable volume. If the exhaust is variable flow, the compliance software shall automatically use either the no sash control or sash control laboratory variable exhaust schedule or a volume-weighted interpolated average of the two schedules if only a fraction of the exhaust hoods have sash control.
Standard Design	Same as the proposed design for non-covered process spaces Exhaust schedules for kitchen exhaust hoods are prescribed and specified in Appendix 5.4B. For laboratory spaces, the standard design is constant volume if the proposed exhaust system is constant volume and has a minimum exhaust air flow rate greater than 10 ACH. Otherwise, the standard design is variable volume. If the standard design is variable volume and the proposed laboratory space is fume hood intense (as defined in Standards Table 140.9-B) then the standard design will use the Appendix 5.4B modified VAV schedule for hoods with sash controls, volume-weighted by the fraction of exhaust that is served by exhaust hoods with vertical-only sashes. If the standard design is variable volume and the proposed space is not fume hood intense then the standard design shall use the VAV exhaust schedule for non-controlled sashes. For healthcare facilities, same as the proposed design.
Standard Design: Existing Buildings

Exhaust Fan Fraction Sash Control
Applicability	Zones with laboratory exhaust hoods with vertical sashes.
Definition	The airflow-weighted fraction of exhaust hoods with vertical sashes that have automatic sash controls. This input is needed to appropriately model cases where only a fraction of the exhaust hoods that have automatic sash controls.
Units	Fraction
Input Restrictions	As Designed (between 0 and 1)
Standard Design	1 if sash controls are required for the laboratory space (per Table 140.9-B of the Standards) For healthcare facilities, same as the Proposed Design.
Standard Design: Existing Buildings	As Designed (between 0 and 1)

5.6.6.4 Outdoor Air Ventilation

Ventilation Source
Applicability	All thermal zones
Definition	The source of ventilation for a thermal zone. The choices are: • Natural (by operable openings) • Forced (by fan)
Units	List: None, Natural, or Forced
Input Restrictions	For hotel/motel guest rooms, as designed. For all other occupancies, Forced.
Standard Design	For residential units, Forced; ventilation shall be provided by a balanced fan system in each zone. For hotel/motel guest rooms, labs, and healthcare facilities, same as the proposed. For other occupancies, Forced.
Standard Design: Existing Buildings

Ventilation Standard
Applicability	Thermal zones with special ventilation requirements, such as a process space, which have no defined requirements in Title 24
Definition	Minimum ventilation rates for: • Title 24 (default) • Other
Units	List: See above
Input Restrictions	None User should be prepared to show justification for not using Title 24 ventilation source. If ‘Other’ is used, the user must enter a description of which standard applies, such as OSHPD3, Animal Shelter, etc.
Standard Design	Same as proposed
Standard Design: Existing Buildings	Same as proposed

Design Ventilation Rate
Applicability	All thermal zones
Definition	The quantity of ventilation air that is provided to the space for the specified thermal zone at maximum occupancy. This is adjusted by the occupancy fraction to determine the design ventilation rate for the space.
Units	cfm
Input Restrictions	To accommodate transfer air requirements for makeup air for exhaust from other zones, the design ventilation rate may be between 95 percent and 120 percent of the code required ventilation rate for high-rise residential spaces and thermal zones, or between 95 percent and 110 percent of code required ventilation rates for all other buildings on a building story without penalty. As defined by the user, provided that the total outside air ventilation rate to the building story matches the standard design outside air ventilation rate for the building story within a specified tolerance (within 20%). Ventilation rates below 95% of the code required ventilation rate for a building story are not allowed. If the ventilation source is natural for residential dwelling spaces, then the proposed design ventilation rate for compliance model purposes shall be zero.
Standard Design	For labs and healthcare facilities, same as the Proposed Design. If the total exhaust airflow requirement on the building floor does not exceed the total ventilation requirement, then the standard design outside air ventilation rate shall be the same as the proposed, if the design ventilation rate is between the limits defined above (95% and 120% of code minimum for high-rise residential spaces, and 95% and 110% for all other buildings.. If the proposed ventilation rate exceeds the limits above, , the standard design ventilation rate for each space shall be the proposed rate uniformly reduced such that the total ventilation air delivered to the building story is equal to the maximum allowed ventilation air rate: Design Ventilation Rate_std = Design Ventilation Rate_prop x ( BFVent_std / BFVent_prop ) Where: BFVent_min is the building floor design minimum required ventilation flow, as specified by the standards, and BFVent_prop is the building floor design ventilation flow for the proposed design.
Standard Design: Existing Buildings	Same as the proposed, if unaltered. If space type is altered such that different ventilation rate requirements apply, the outside air ventilation rate should follow the same rules as for new construction.

Occupancy Fraction
Applicability	All thermal zones
Definition	The space design requirements for ventilation at design occupancy that are compliant with space egress requirements and design ventilation requirements. The occupancy fraction also affects hot water use requirements for the space.
Units	Unitless fraction
Input Restrictions	Default of 0.5 as designed with a minimum value of 0.5 and a maximum value of 5
Standard Design	0.5
Standard Design: Existing Buildings	0.5

Building Floor Ventilation Requirement
Applicability	Internal variable, calculated for each building story (floor)
Definition	The total outside air ventilation airflow requirement for all spaces on a building story or floor. This is calculated by summing the ventilation levels for each space, and comparing it to the minimum required ventilation rate and the design exhaust air flow requirements.
Units	cfm (ft³/min)
Input Restrictions	Not a user input; derived by summing the ventilation and exhaust air flows from all spaces on the building floor
Standard Design	For labs and healthcare facilities, same as the Proposed Design. For all other spaces: This is calculated by the following procedure: 1. Calculate the proposed ventilation for the building story as the sum of design ventilation flow for each space included on a building story, including all spaces except space designated as lab space. 2. Calculate the proposed exhaust for the building story as the sum of design exhaust flow for each space on the building story, including all spaces except spaces designated as lab space. 3. Calculate the code minimum ventilation requirement as the sum of all minimum required ventilation airflows, as defined by Appendix 5.4A, for all spaces in the building story. 4. If the proposed exhaust is greater than the code minimum ventilation rate, then: a. Total standard design building story ventilation requirement shall be: Standard ventilation = Min (proposed ventilation, proposed exhaust x 1.2) Otherwise: Standard ventilation = Min (code minimum ventilation, proposed ventilation)
Standard Design: Existing Buildings

Minimum Ventilation Rate
Applicability	All thermal zones that have variable ventilation control.
Definition	The minimum quantity of ventilation air that must be provided to the space when it is occupied
Units	cfm (ft³/min)
Input Restrictions	As designed but not lower than code minimum (default value) The default value shall be the larger of 15 cfm times the design occupancy times the occupancy fraction or the conditioned floor area times the applicable ventilation rate from Appendix 5.4A. For spaces where demand control ventilation is installed, the minimum ventilation rate is specified by the greater of the rate in Table 120.1-A or 15 cfm times the scheduled occupancy for that hour. For residential spaces where the proposed design ventilation source is natural ventilation, the minimum ventilation rate shall be zero.
Standard Design	For labs and healthcare facilities, same as the Proposed Design. For spaces where demand control ventilation is required, the minimum ventilation rate is specified by the greater of the rate in Appendix 5.4A or 15 cfm times the scheduled occupancy for that hour.
Standard Design: Existing Buildings

Ventilation Control Method
Applicability	All thermal zones
Definition	The method used to determine outside air ventilation needed for each hour in the simulation. This information is reported to the system serving the zone. The method of controlling outside air at the system level in response to this information is discussed under secondary systems. Options at the zone level are: • CO2 sensors in the space: The outside air is varied to maintain a maximum CO2 concentration in the space. This shall be approximated by multiplying the ventilation rate per occupant times the number of occupants for that hour. (When turnstile counts are used to automatically adjust ventilation levels based on occupancy, this method may also be used.) • Fixed ventilation rate: Outside air is delivered to the zone at a constant rate and is equal to the design ventilation rate (see above).
Units	List (see above)
Input Restrictions	As designed If the space includes a design occupant density greater than or equal to 25 persons per 1,000 ft², and the system includes an airside economizer, or if the design airflow rate for the system exceeds 3,000 cfm, the input is restricted to CO2 sensors in the space. Note: a classroom space greater than 750 ft²must have an occupancy sensor for ventilation control and setback to meet the mandatory Title 24 Standards requirements of 120.2(e)3. This requirement should be indicated on the appropriate compliance form submittal.
Standard Design	For healthcare facilities, same as the Proposed Design. If the default occupancy for the specified space function from Appendix 5.4B is greater than or equal to 25 persons per 1,000 ft² and the system includes an airside economizer, set control method to CO2 sensors in the space. Otherwise, set to fixed ventilation rate.
Standard Design: Existing Buildings