Volume flow rates of the rooms –Residential ventilation

1.

Calculate the volume flow rate for external air for the use unit
2. Adapt the volume flow rate for external air for the use unit
3. Adapt supply air volume flow rate for individual rooms

Calculate the volume flow rates which result from the conditions of the use unit.

  1. Activate the tab: Air Flow

  2. Check the requirement for the calculation of Maximum selected::

    Comparison value for determining the extract volume flow rate for the usage unit based on the number of persons and the volume flow rate per person.

    1. Activate the tab: Design Criteria

    2. Check settings in

      Number of people who typically are present in the use unit.

      Necessary external air volume flow rate per person.

    Comparison value for determining the extract volume flow rate for the usage unit based on the room types and their requirements.

    Each room uses a product from the product database. The parameters relevant for ventilation are stored in the product.

    1. Close all dialogs.

    2. Start the function ClosedRoom.
      The cursor appears as a crosshair.

    3. Click in the desired room. The dialog appears.
    4. Select a product. Click .... The product database appears.
    5. Select the desired entry by double clicking .

    The values are stored in the product database.

    Room type (h) Extract volume flow rate in m³/h in the case of nominal ventilation (g,h)
    Utility room 20 (c,d)
    Cellar room (e.g. hobby room) (a,f)
    WC
    Kitchen, kitchenette (b) 40
    Bathroom with/without toilet
    Shower room
    Sauna or fitness room 40 (e)

    (a) Heated and within the thermal envelope.

    (b) Intensive ventilation of windowless rooms: The building authority guideline requires 200 m³/h for windowless kitchens.

    (c) If so required by the ventilation concept of the usage unit, the corridor can also be planned so that it has an extract volume flow rate of 20 m³/h.

    (d) If a room is to be used for drying laundry, e.g. on a drying stand, an extract volume flow rate of 40 m³/h must be planned.

    (e) Alternatively, the volume flow can be determined according to the expected moisture condensation considering aspects of building protection.

    (f) Rooms, the uses of which cause elevated levels of humidity and/or substance concentrations, are handled separately.

    (g) When designing using equation (28), no reduction below 50% of the value in table 16 is permitted.

    (h) Additional rooms, such as storage, dressing or utility rooms, can also be included in the ventilation concept as extract-air rooms by taking into account the use conditions which must be assumed for design purposes (the moisture loads to be expected).

    Comparison value for determining the extract volume flow rate for the usage unit on the basis of its area. The value is calculated automatically. The size of the usage unit determines the method.

    Equation 8 of DIN 1946-6 is applied, whereby the value is set to 20 m²:

    Factor for consideration of the ventilation stage; =1 (nominal ventilation)
    set to 20 m²

    Equation 8 of DIN 1946-6 is applied.

    Factor for consideration of the ventilation stage; =1 (nominal ventilation)
    Area of the usage unit according to DIN 1946-6

    Equation 8 of DIN 1946-6 is applied in adapted form. According to DIN 1946-6, Table 7, Note C, the result is:

    Factor for consideration of the ventilation stage; =1 (nominal ventilation)
    Area of the usage unit according to DIN 1946-6

  3. Check settings in

    Effective air volume flow rate through infiltration, in m³/h

    Setting Effect

    Activates the consideration of infiltration for the calculation of the air volume flow rate in the usage unit. Clicking on Calculate displays the calculated value.

    Volume flow rate coefficient

    A design criterion (room) of the heating load calculation influences this value:

    Combustion air flow ()Closed(Volume flow which is mechanically discharged from a heated room (i) and is not included in the extract volume flow rate (e.g. for combustion air))

    1. Close all dialogs.
    2. Select: Tools Heat Load Calculation (EN 12831-1 2017). The dialog appears.
    3. Select the desired room in the tree structure.
    4. In the Design criteria area, activateAdvanced view

    5. Check settings in

      Volume flow which is mechanically discharged from a heated room (i) and is not included in the extract volume flow rate (e.g. for combustion air)

      According to ClosedDIN 1946-6, Table 9 the result is:

      • = 0.21, if =0
      • = 0.17, if >0 OR Ventilation system= supply air
      Ventilation system Type
      Mechanical ventilation Extract air With no furnace requiring room air 0.21
      With furnace requiring room air (a) 0.17
      Supply air 0.17
      Supply/Extract air Not needed
      Ventilation system to DIN 18017-3 With no furnace requiring room air 0.21
      With furnace requiring room air (a) 0.17
      (a) The reduced eZ ensures that no negative pressure greater than 4 Pa occurs during operation.

    Sum of the volumes of all rooms in this usage unit.

    Air change rate at 50 Pa
    No consideration of infiltration.

  4. Click Calculate. DDScad performs the calculation:

    1. Calculation of the three comparison values from step 2)
    2. Acceptance of the maximum after Maximum selected:,
    3. Subtraction of the value in Infiltration qv.: (step 3).
    4. The result appears as a proposal in Selected extract:.