Details on Ventilation
Information on the Ventilation section in the Heat load tab of the room level.
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Ventilation system
In the heat load calculation according to DS 418, the Ventilation System can only be set at project or ventilation zone level. If a supply air and/or exhaust air system has been selected at the corresponding levels, the settings for this can be adjusted here for the specific room.
When a ventilation system is installed for the room, the supply air volume flow must be heated. This can be done in the room or through an air heater. The heat output required for heating is included in the heating load and results from the temperature difference between the room temperature and the temperature after heat recovery (HR). The temperature difference between the supply air temperature and the temperature after the HR determines the heat output for the air heater.
The choice of the system type is decisive, since the extract air temperature is determined as a mixed temperature from all extract air volume flows of the supply and extract air system, which is used for the calculation of the supply air temperature according to the HR. The following figures illustrate the choice of the air handling unit of a room depending on the unit constellation and the possible settings of the system types.
| Extract air system |  |
| Supply and extract air system |  |
Air change rate: Air change rate to be entered manually. The supply air and extract air volume flow are then calculated. If you change supply air or extract air volume flow, the air change rate is adjusted accordingly based on the larger volume flow rate.
Supply air flow rate: Quantity of air that flows into the room via the ventilation system. If you have also specified the extract air volume flow rate, the air change rate is calculated based on the larger volume flow rate. Clicking on 
opens a context menu in which you can choose between the options Reset to value from CAD and Reset to calculated value. Clicking on Reset to value from CAD enters the value that was determined from CAD when the building was created. Clicking on Reset to calculated value calculates the supply air volume flow with the standard air change rate 1.5 and the room volume.
Extract air flow rate: Quantity of air that is discharged from the room via the ventilation system. If you have also specified the supply air volume flow rate, the air change rate is calculated based on the larger volume flow rate. Clicking on opens a context menu in which you can choose between the options Reset to value from CAD and Reset to calculated value. Clicking on Reset to value from CAD enters the value that was determined from CAD when the building was created. Clicking on Reset to calculated value calculates the supply air volume flow with the standard air change rate 1.5 and the room volume.
Supply air temperature after HR: Displays the temperature of the supply air after heat recovery in supply and extract air systems with heat recovery. The Supply air temperature after HR is used for the calculation of ventilation heat loss of the heat load. The coverage of ventilation heat losses by an air heater in relation to the supply air flow rate and Supply air temperature is displayed in the Results tab.
Supply air temperature: The supply air temperature is suggested as follows, depending on the type of ventilation system:
In supply and extract air systems, the supply air temperature is determined according to standards with the heat recovery rate.
The supply air temperature can also be freely entered, the value then appears in bold. Clicking on opens a context menu in which you can choose between the options Reset to value from CAD and Reset to calculated value. Clicking on Reset to value from CAD enters the value that was determined from CAD when the building was created.
Minimum volume flow rate
spec. volume flow through joints: Infiltration through window and door joints. This value is determined automatically based on standards, but can be adjusted. Click 
to reset the value to the automatically determined value.
Air change rate: Quotient of volume flow and inner room volume. The air exchange rate is determined automatically, but can be adjusted. Clicking on for the spec. volumetric flow field sets the automatically determined value again.
spec. volumetric flow: Volume flow by infiltration per square meter of enveloping surface This value is determined automatically, but can be adjusted. Clicking on opens a context menu in which you can choose between the options Reset to value from CAD and Reset to calculated value. Clicking on Reset to value from CAD enters the value that was determined from CAD when the building was created. Click Reset to calculated value to reset the value to the automatically determined value.
Volume flow rate: Inflowing air due to infiltration. This value is determined with the area of the room either from the values Air exchange rate or spec. volumetric flow (if these were specified manually) or from a standard-based specific volumetric flow. The value can be adjusted. Clicking on for the spec. volumetric flow field sets the automatically determined value again.