Ventilation in pressurized rooms can be defined as the rate of airflow through a room to remove and dilute air contaminants. The application sets supply and extract airflow rates to satisfy ventilation requirements. In a positive pressure room the ventilation rate equals supply flow. In a negative room, it equals extract flow. The pressurized room application has three options for ventilation control:
- Minimum ventilation collaborates with the room pressure control application for ventilation purposes. The ventilation rate is selected from a set of configured values based on room operating mode and HVAC plant mode.
- Minimum ventilation and demand-controlled ventilation DCV collaborates with the room pressure control application for ventilation and/or room air quality control purposes. The current ventilation rate for a room is selected from a set of configured values based on room operating mode, HVAC plant mode and measured CO2 concentration. The minimum flow depends on occupancy. The DCV function can be disabled according to occupancy.
- Minimum ventilation and external demand-controlled ventilation DCV collaborates with the room pressurization application for ventilation and/or room air quality control purposes. The current ventilation rate for a room is based on occupancy and a DCV signal generated by a separate controller, device or system (by others) and written to an object in this application function. The minimum flow depends on occupancy. The DCV function can be disabled according to occupancy.
The pressurized room application configures a minimum supply air flow in the temperature control dead zone. The function can be configured individually for all room operating modes.
Description | Name | Default value |
|---|---|---|
Minimum room ventilation for comfort This is the ventilation rate needed in the room during Comfort mode. The value must come from the ventilation engineer’s specifications. It may be specified as the "occupied ventilation rate" or as the only ventilation rate for the room. | RVntMinCmf | 0 |
Minimum room ventilation for pre-comfort | RVntMinPcf | 0 |
Minimum room ventilation for economy | RVntMinEco | 0 |
Minimum room ventilation for protection If Protection is not specified, the value for Economy might be used. | RVntMinPrt | 0 |
Air quality control for minimum ventilation and demand-controlled ventilation DCV
The application can be used for air quality control. The room must have an air quality sensor. The application automatically enables air quality control as soon as an air quality sensor is configured.
Air quality setpoints can be configured or disabled separately for each room operating mode.
The maximum air volume flows for a VAV actuator can be configured for each air terminal. The sequence diagram illustrates an example of possible relationships between air flow levels for the various HVAC functions. When the flow needed for ventilation is more than the flow needed for heating or cooling, the ventilation requirement takes effect.
Description | Name | Default value |
|---|---|---|
Supply air VAV maximum air flow for ventilation | VavSuAflMaxVnt | 100 [m3/h] |
Volume flow
setpoints
| ||||
| VAV volume flow |
| TR | Room temperature |
SpH | Effective heating setpoint |
| SpC | Effective cooling setpoint |
VavSuAirFlMaxH | Maximum air volume flow heating |
| VavSuAirFlMaxC | Maximum air volume flow cooling |
VavSuAirFlMinH | Minimum air volume flow heating |
| VavSuAirFlMinC | Minimum air volume flow cooling |
VavSuAflMinVnt | Minimum air volume flow for ventilation |
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Figure: Volume flow setpoints