Buildings.Controls.OBC.ASHRAE.G36.AHUs.MultiZone.VAV.SetPoints.OutdoorAirFlow.Title24
Complying California Title 24
Information
This package contains sequences to set the minimum outdoor airflow setpoint for compliance with the ventilation rate procedure of California Title 24. It is implemented according to Section 5.16.3.2 of ASHRAE Guideline G36, May 2020.
- Buildings.Controls.OBC.ASHRAE.G36.AHUs.MultiZone.VAV.SetPoints.OutdoorAirFlow.Title24.AHU conducts AHU level calculations for specifying minimum outdoor airflow rate,
- and Buildings.Controls.OBC.ASHRAE.G36.AHUs.MultiZone.VAV.SetPoints.OutdoorAirFlow.Title24.SumZone finds the sums of outputs from zone level calculations. They become inputs of AHU level calculation.
Package Content
| Name | Description |
|---|---|
 AHU
|
AHU level setpoint calculation |
 SumZone
|
Sum of the zone level setpoints calculation |
 Validation
|
Collection of validation models |
Buildings.Controls.OBC.ASHRAE.G36.AHUs.MultiZone.VAV.SetPoints.OutdoorAirFlow.Title24.AHU
AHU level setpoint calculation
Information
This sequence outputs AHU level effective outdoor air absolute minimum and design
minimum setpoints VEffAbsOutAir_flow, VEffDesOutAir_flow and
the nomalized minimum setpoint effOutAir_normalized
when complying with California Title 24 ventilation requirements.
It is implemented according to Section 5.16.3.2 of ASHRAE
Guideline G36, May 2020.
It calculates as below:
-
See the sum of zone absolute and design minimum outdoor airflow setpoint
VSumZonAbsMin_flowandVSumZonDesMin_flowfrom Buildings.Controls.OBC.ASHRAE.G36.AHUs.MultiZone.VAV.SetPoints.OutdoorAirFlow.Title24.SumZone for the detailed description. -
Effective outdoor air absolute minimum and design minimum setpoints
(
VEffAbsOutAir_flowandVEffDesOutAir_flow) are recalculated continuously based on the mode of the zones being served.-
Effective outdoor air absolute minimum setpoint
VEffAbsOutAir_flowis the sum ofVZonAbsMin_flowfor all zones in all zone groups that are in occupied mode but shall be no larger than the absolute minimum outdoor airflowVAbsOutAir_flow. -
Effective outdoor air design minimum setpoint
VEffDesOutAir_flowis the sum ofVZonDesMin_flowfor all zones in all zone groups that are in occupied mode but shall be no larger than the absolute minimum outdoor airflowVDesOutAir_flow.
-
Effective outdoor air absolute minimum setpoint
-
According to section 5.16.4, 5.16.5 and 5.16.6, the effective minimum outdoor airflow
setpoint should be reset based on the highest zone CO2 control- loop signal from
VEffAbsOutAir_flowat 50% signal toVEffDesOutAir_flowat 100% signal. When there is no CO2 sensor in any zone, the effective minimum outdoor airflow setpoint should be equal to theVEffDesOutAir_flow.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Boolean | have_CO2Sen | True: there are zones have CO2 sensor | |
| Economizer design | |||
| OutdoorAirSection | minOADes | Type of outdoor air section | |
| Nominal condition | |||
| Real | VAbsOutAir_flow | Design outdoor airflow rate when all zones with CO2 sensors or occupancy sensors are unpopulated [m3/s] | |
| Real | VDesOutAir_flow | Design minimum outdoor airflow rate with the areas served by the system are occupied at their design population, including diversity where applicable [m3/s] | |
Connectors
| Type | Name | Description |
|---|---|---|
| input RealInput | VSumZonAbsMin_flow | Sum of the zone absolute minimum outdoor airflow setpoint [m3/s] |
| input RealInput | VSumZonDesMin_flow | Sum of the zone design minimum outdoor airflow setpoint [m3/s] |
| input RealInput | uCO2Loo_max | Maximum Zone CO2 control loop [1] |
| input RealInput | VAirOut_flow | Measured outdoor air volumetric flow rate [m3/s] |
| output RealOutput | VEffAbsOutAir_flow | Effective outdoor air absolute minimum setpoint [m3/s] |
| output RealOutput | effAbsOutAir_normalized | Effective minimum outdoor airflow setpoint, normalized by the absolute outdoor airflow rate [1] |
| output RealOutput | VEffDesOutAir_flow | Effective outdoor air design minimum setpoint [m3/s] |
| output RealOutput | effDesOutAir_normalized | Effective minimum outdoor airflow setpoint, normalized by the design outdoor airflow rate [1] |
| output RealOutput | effOutAir_normalized | Effective minimum outdoor airflow setpoint, normalized by the design total outdoor airflow rate [1] |
| output RealOutput | outAir_normalized | Normalized outdoor airflow rate [1] |
Modelica definition
block AHU "AHU level setpoint calculation"
parameter Buildings.Controls.OBC.ASHRAE.G36.Types.OutdoorAirSection minOADes
"Type of outdoor air section";
parameter Boolean have_CO2Sen
"True: there are zones have CO2 sensor";
parameter Real VAbsOutAir_flow(unit="m3/s")
"Design outdoor airflow rate when all zones with CO2 sensors or occupancy sensors are unpopulated";
parameter Real VDesOutAir_flow(unit="m3/s")
"Design minimum outdoor airflow rate with the areas served by the system are occupied at their design population, including diversity where applicable";
Buildings.Controls.OBC.CDL.Interfaces.RealInput VSumZonAbsMin_flow(
final min=0,
final unit="m3/s",
final quantity="VolumeFlowRate")
"Sum of the zone absolute minimum outdoor airflow setpoint";
Buildings.Controls.OBC.CDL.Interfaces.RealInput VSumZonDesMin_flow(
final min=0,
final unit="m3/s",
final quantity="VolumeFlowRate")
"Sum of the zone design minimum outdoor airflow setpoint";
Buildings.Controls.OBC.CDL.Interfaces.RealInput uCO2Loo_max(
final unit="1")
if have_CO2Sen "Maximum Zone CO2 control loop";
Buildings.Controls.OBC.CDL.Interfaces.RealInput VAirOut_flow(
final min=0,
final unit="m3/s",
final quantity="VolumeFlowRate")
if (minOADes == Buildings.Controls.OBC.ASHRAE.G36.Types.OutdoorAirSection.DedicatedDampersAirflow
or minOADes == Buildings.Controls.OBC.ASHRAE.G36.Types.OutdoorAirSection.SingleDamper)
"Measured outdoor air volumetric flow rate";
Buildings.Controls.OBC.CDL.Interfaces.RealOutput VEffAbsOutAir_flow(
final min=0,
final unit="m3/s",
final quantity="VolumeFlowRate")
"Effective outdoor air absolute minimum setpoint";
Buildings.Controls.OBC.CDL.Interfaces.RealOutput effAbsOutAir_normalized(
final unit="1")
"Effective minimum outdoor airflow setpoint, normalized by the absolute outdoor airflow rate ";
Buildings.Controls.OBC.CDL.Interfaces.RealOutput VEffDesOutAir_flow(
final min=0,
final unit="m3/s",
final quantity="VolumeFlowRate")
"Effective outdoor air design minimum setpoint";
Buildings.Controls.OBC.CDL.Interfaces.RealOutput effDesOutAir_normalized(
final unit="1")
"Effective minimum outdoor airflow setpoint, normalized by the design outdoor airflow rate ";
Buildings.Controls.OBC.CDL.Interfaces.RealOutput effOutAir_normalized(
final unit="1")
"Effective minimum outdoor airflow setpoint, normalized by the design total outdoor airflow rate ";
Buildings.Controls.OBC.CDL.Interfaces.RealOutput outAir_normalized(
final unit="1")
if (minOADes == Buildings.Controls.OBC.ASHRAE.G36.Types.OutdoorAirSection.DedicatedDampersAirflow
or minOADes == Buildings.Controls.OBC.ASHRAE.G36.Types.OutdoorAirSection.SingleDamper)
"Normalized outdoor airflow rate";
Buildings.Controls.OBC.CDL.Reals.Sources.Constant absOutAir(
final k=VAbsOutAir_flow)
"Design outdoor airflow rate when all zones with CO2 sensors or occupancy sensors are unpopulated";
Buildings.Controls.OBC.CDL.Reals.Min min1
"Effective outdoor air absolute minimum setpoint";
Buildings.Controls.OBC.CDL.Reals.Sources.Constant desOutAir(
final k=VDesOutAir_flow)
"Design minimum outdoor airflow with areas served by the system are occupied at their design population, including diversity where applicable";
Buildings.Controls.OBC.CDL.Reals.Min min2 "Effective outdoor air design minimum setpoint";
Buildings.Controls.OBC.CDL.Reals.Divide norVOutMin
"Normalization for minimum outdoor air flow rate";
Buildings.Controls.OBC.CDL.Reals.Divide norVOutMin1
"Normalization for minimum outdoor air flow rate";
Buildings.Controls.OBC.CDL.Reals.Sources.Constant con(
final k=0.5) if have_CO2Sen
"Constant value";
Buildings.Controls.OBC.CDL.Reals.Sources.Constant con1(
final k=1) if have_CO2Sen
"Constant value";
Buildings.Controls.OBC.CDL.Reals.Line effOutAir(
final limitBelow=false,
final limitAbove=true) if have_CO2Sen
"Normalized effective outdoor air setpoint";
Buildings.Controls.OBC.CDL.Reals.MultiplyByParameter gai(
final k=1) if not have_CO2Sen
"When there is no zone has CO2 sensor, design setpoint will be applied";
Buildings.Controls.OBC.CDL.Reals.Divide norVOutMin2 if have_CO2Sen
"Normalization for minimum outdoor air flow rate";
Buildings.Controls.OBC.CDL.Reals.Divide norVOut
if (minOADes == Buildings.Controls.OBC.ASHRAE.G36.Types.OutdoorAirSection.DedicatedDampersAirflow
or minOADes == Buildings.Controls.OBC.ASHRAE.G36.Types.OutdoorAirSection.SingleDamper)
"Normalization for outdoor air flow rate";
Buildings.Controls.OBC.CDL.Reals.Sources.Constant neaZer(
final k=1E-4)
"Near zero value";
Buildings.Controls.OBC.CDL.Reals.Max max2
"Avoid devide by zero";
Buildings.Controls.OBC.CDL.Reals.Max max1
"Avoid devide by zero";
equation
connect(absOutAir.y, min1.u1);
connect(min1.y, VEffAbsOutAir_flow);
connect(desOutAir.y, min2.u1);
connect(min2.y, VEffDesOutAir_flow);
connect(VSumZonDesMin_flow, min2.u2);
connect(VSumZonAbsMin_flow, min1.u2);
connect(min1.y, norVOutMin1.u1);
connect(min2.y, norVOutMin.u1);
connect(norVOutMin1.y, effAbsOutAir_normalized);
connect(norVOutMin.y, effDesOutAir_normalized);
connect(uCO2Loo_max, effOutAir.u);
connect(con.y, effOutAir.x1);
connect(con1.y, effOutAir.x2);
connect(gai.y, effOutAir_normalized);
connect(min2.y, effOutAir.f2);
connect(min1.y, effOutAir.f1);
connect(norVOutMin.y, gai.u);
connect(effOutAir.y, norVOutMin2.u1);
connect(norVOutMin2.y, effOutAir_normalized);
connect(VAirOut_flow, norVOut.u1);
connect(norVOut.y, outAir_normalized);
connect(max2.y, norVOutMin1.u2);
connect(neaZer.y, max2.u2);
connect(absOutAir.y, max2.u1);
connect(neaZer.y, max1.u2);
connect(desOutAir.y, max1.u1);
connect(max1.y, norVOutMin.u2);
connect(max1.y, norVOutMin2.u2);
connect(max1.y, norVOut.u2);
end AHU;
Buildings.Controls.OBC.ASHRAE.G36.AHUs.MultiZone.VAV.SetPoints.OutdoorAirFlow.Title24.SumZone
Sum of the zone level setpoints calculation
Information
This sequence sums up zone level minimum outdoor airflow setpoints when complying with California Title 24 ventilation requirements. It is implemented according to Section 5.16.3.2 of ASHRAE Guideline G36, May 2020.
It calculates following values:
-
Sum of the zone absolute minimum outdoor airflow setpoint
VZonAbsMin_flowfor all zones in all zone groups that are in occupied mode. -
Sum of the zone design minimum outdoor airflow setpoint
VZonDesMin_flowfor all zones in all zone groups that are in occupied mode. -
Maximum zone level CO2 control loop signal
yMaxCO2.
See the zone absolute and design minimum outdoor airflow setpoint
VZonAbsMin_flow and VZonDesMin_flow from
Buildings.Controls.OBC.ASHRAE.G36.VentilationZones.Title24.Setpoints for the detailed
description.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Integer | nZon | Total number of serving zones | |
| Integer | nGro | Total number of groups | |
| Integer | zonGroMat[nGro, nZon] | Zone matrix with zone group as row index and zone as column index. It flags which zone is grouped in which zone group | |
| Boolean | have_CO2Sen | True: some zones have CO2 sensor |
Connectors
| Type | Name | Description |
|---|---|---|
| input IntegerInput | uOpeMod[nGro] | Groups operation mode |
| input RealInput | VZonAbsMin_flow[nZon] | Zone absolute minimum outdoor airflow setpoint [m3/s] |
| input RealInput | VZonDesMin_flow[nZon] | Zone design minimum outdoor airflow setpoint [m3/s] |
| input RealInput | uCO2[nZon] | Zone CO2 control loop [1] |
| output RealOutput | VSumZonAbsMin_flow | Sum of the zone absolute minimum outdoor airflow setpoint [m3/s] |
| output RealOutput | VSumZonDesMin_flow | Sum of the zone design minimum outdoor airflow setpoint [m3/s] |
| output RealOutput | yMaxCO2 | Maximum CO2 control loop signal [1] |
Modelica definition
block SumZone "Sum of the zone level setpoints calculation"
parameter Integer nZon
"Total number of serving zones";
parameter Integer nGro
"Total number of groups";
parameter Integer zonGroMat[nGro, nZon]
"Zone matrix with zone group as row index and zone as column index. It flags which zone is grouped in which zone group";
parameter Boolean have_CO2Sen
"True: some zones have CO2 sensor";
Buildings.Controls.OBC.CDL.Interfaces.IntegerInput uOpeMod[nGro]
"Groups operation mode";
Buildings.Controls.OBC.CDL.Interfaces.RealInput VZonAbsMin_flow[nZon](
final min=fill(0,nZon),
final unit=fill("m3/s",nZon),
final quantity=fill("VolumeFlowRate",nZon))
"Zone absolute minimum outdoor airflow setpoint";
Buildings.Controls.OBC.CDL.Interfaces.RealInput VZonDesMin_flow[nZon](
final min=fill(0,nZon),
final unit=fill("m3/s",nZon),
final quantity=fill("VolumeFlowRate",nZon))
"Zone design minimum outdoor airflow setpoint";
Buildings.Controls.OBC.CDL.Interfaces.RealInput uCO2[nZon](
final unit=fill("1",nZon)) if have_CO2Sen
"Zone CO2 control loop";
Buildings.Controls.OBC.CDL.Interfaces.RealOutput VSumZonAbsMin_flow(
final min=0,
final unit="m3/s",
final quantity="VolumeFlowRate")
"Sum of the zone absolute minimum outdoor airflow setpoint";
Buildings.Controls.OBC.CDL.Interfaces.RealOutput VSumZonDesMin_flow(
final min=0,
final unit="m3/s",
final quantity="VolumeFlowRate")
"Sum of the zone design minimum outdoor airflow setpoint";
Buildings.Controls.OBC.CDL.Interfaces.RealOutput yMaxCO2(
final unit="1")
if have_CO2Sen
"Maximum CO2 control loop signal";
Buildings.Controls.OBC.CDL.Reals.MatrixGain groFlo(
final K=zonGroMat)
"Vector of total zone flow of each group";
Buildings.Controls.OBC.CDL.Reals.MatrixGain groFlo1(
final K=zonGroMat)
"Vector of total zone flow of each group";
Buildings.Controls.OBC.CDL.Conversions.BooleanToReal booToRea[nGro]
"Convert boolean to real";
Buildings.Controls.OBC.CDL.Reals.Multiply mul[nGro]
"Find the total flow of zone group";
Buildings.Controls.OBC.CDL.Reals.Multiply mul1[nGro]
"Find the total flow of zone group";
Buildings.Controls.OBC.CDL.Reals.MultiSum mulSum(
final nin=nGro)
"Sum of the zone absolute minimum outdoor airflow setpoint";
Buildings.Controls.OBC.CDL.Reals.MultiSum mulSum1(
final nin=nGro)
"Sum of the zone design minimum outdoor airflow setpoint";
Buildings.Controls.OBC.CDL.Integers.Sources.Constant occMod[nGro](
final k=fill(Buildings.Controls.OBC.ASHRAE.G36.Types.OperationModes.occupied,nGro))
"Occupied mode index";
Buildings.Controls.OBC.CDL.Integers.Equal intEqu1[nGro]
"Check if operation mode is occupied";
Buildings.Controls.OBC.CDL.Reals.MultiMax mulMax(
final nin=nZon) if have_CO2Sen
"Maximum CO2 loop signal";
equation
connect(uOpeMod, intEqu1.u1);
connect(occMod.y, intEqu1.u2);
connect(VZonAbsMin_flow, groFlo.u);
connect(intEqu1.y, booToRea.u);
connect(groFlo.y, mul.u2);
connect(booToRea.y, mul.u1);
connect(booToRea.y, mul1.u1);
connect(groFlo1.y, mul1.u2);
connect(mul.y, mulSum.u);
connect(mul1.y, mulSum1.u);
connect(VZonDesMin_flow, groFlo1.u);
connect(mulSum.y, VSumZonAbsMin_flow);
connect(mulSum1.y, VSumZonDesMin_flow);
connect(uCO2, mulMax.u);
connect(mulMax.y, yMaxCO2);
end SumZone;