Stencil: Zone HVAC Stencil: Grp-VAV Terminal
Type: Air Terminal
Sub Type: VAV_NoReheat
EnergyPlus Object - AirTerminal:SingleDuct:VAV:NoReheat
Variable air volume (VAV) systems control the dry-bulb temperature inside a zone by varying the supply air volume instead of the air temperature. At full cooling the VAV damper is fully open supplying the specified maximum air flow rate. As the cooling load decreases, the damper closes until it reaches the minimum stop specified by the zone minimum air flow fraction.
VAV systems can be used for interior or perimeter zones with a common fan system and air temperature control. The VAV concept may vary according to the VAV box locations and air temperature controls. Heating can be provided if necessary by use of baseboard.
The table shows the properties that are displayed when the component is selected while in diagram mode. The second column shows the selection options available that are dictated by EnergyPlus or it shows the source for the library entries that are displayed in the drop down list.
| Property Name | Value Sources/Options |
|
Name |
Simergy provides unique name (editable) |
|
Availability Schedule Name |
Schedules |
|
Maximum Air Flow Rate |
0-Min; Autosize |
|
Zone Minimum Air Flow Method |
Scheduled, Fixed Flow Rate, Constant |
|
Constant Minimum Air Flow Fraction |
0 to 1; fraction of max air flow rate |
|
Fixed Minimum Air Flow Rate |
0 to 1 |
|
Minimum Air Flow Fraction Schedule Name |
Schedules |
|
Design Specification Outdoor Air Object Name |
SizingParams/HVACDesign/OutdoorAirDesignSpec |
Simergy automatically defines a unique name for each component. This can be changed by the user if desired.
Schedule that this component will operate or is available to operate.
The design maximum volume flow rate (m3/sec) specified for VAV ADU. This is autosizable.
This field is used to select how the program will determine the minimum flow rate to the zone while the system is operating. The minimum flow rate is modeled as a fraction of the maximum flow rate. There are five choices: Constant, FixedFlowRate, Scheduled, Sum and Maximum. If Constant is entered, then the program will use the value for minimum flow fraction entered in the following field. If FixedFlowRate is entered, then the program will use the value for minimum flow rate entered in the field below called Fixed Minimum Air Flow Rate. If Scheduled is entered, then the program will obtain the value for minimum flow fraction from the schedule named in the field below called Minimum Air Flow Fraction Schedule Name. Sum and Maximum are used to either provide the summation of all “entered” inputs or the maximum of all “entered” inputs.
The minimum flow rate to the zone while the system is operating, specified as a fraction of the maximum air flow rate. The minimum zone fraction is normally specified to meet the minimum ventilation requirement for the occupants. This field is only used if the Zone Minimum Air Flow Method field is set to Constant.
The minimum flow rate to the zone while the system is operating, specified as a fixed minimum air flow rate in meters cubed per second. The minimum air flow rate is normally specified to meet the minimum ventilation requirement for the occupants. This field is only used if the Zone Minimum Air Flow Method field is set to FixedFlowRate.
The name of a schedule that determines the value of the minimum air flow fraction. The schedule should contain fractions from 0.0 to 1.0. These values will define the minimum flow rate to the zone while the system is operating, specified as a fraction of the maximum air flow rate. This field is only used if the Zone Minimum Air Flow Method field is set to Scheduled.
This alpha field specifies the name of a DesignSpecification:OutdoorAir object. When this field is used, the terminal unit will increase flow as needed to meet this outdoor air requirement. If Outdoor Air Flow per Person is non-zero, then the outdoor air requirement will be computed based on the current number of occupants in the zone. At no time will the supply air flow rate exceed the value for Maximum Air Flow Rate. If this field is blank, then the terminal unit will not be controlled for outdoor air flow. See documentation for the zone HVAC outdoor air object for further information (Ref DesignSpecification:OutdoorAir).
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