P&K KFA (VDI 3781 part 4)

Parameter

Parameter

The form is used to define global settings for the project.

Project Title

The project title will be included in the output of graphics and reports.

Buildingblocks (Expert Mode)

The directive stipulates in chapter 6.2.2.2 the consideration of closed building groups when determining the recirculation zone of upstream buildings. P&K KFA integrates a general block analysis of the surrounding development.

The program automatically adds to the list of recirculation zones of the upstream buildings the recirculation zones of the virtual block buildings. These blocks will be generated from those buildings in the relevant neighborhood of the exhaust house, which meet the following criteria:

  1. The buildings must exceed a height: Default higher than half the height of the exhaust house.
  2. The distance between buildings must be below a minimum distance: Default less than 4m.

A block is a flat roof building that encloses all the buildings integrated into it. In addition to the recirculation zones of all individual buildings, blocks are also taken into account in the determination of the height of the exhaust gas discharge system.

The two criteria for blocking can be adjusted as follows:

  1. For the minimum height:
    1. Height is not relevant. All surrounding buildings are included
    2. same height as the exhaust house
    3. half height of the exhaust house
    4. third height of the exhaust house
    5. quarter height of the exhaust house
  2. For the maximum building distance: 1m to 15m
Version 2.24

Recirculation zone according guideline

When calculating the recirculation zone, the guideline distinguishes between the route above the discharge building and the route outside the building. In two cases this leads to a discontinuity of the recirculation zone at the edge of upstream buildings.

1. Upstream ridge roofs
Above the building, the recirculation increases to the maximum height H2 and outside the building, the recirculation zone at the edge of the building always starts at the height H2. This then leads to a discontinuity at the edge of the building if the height H2 is only reached outside the building floor plan. Alternatively, P&K KFA offers the option of setting the starting height of the recirculation zone at the edge of the building to the value reached above the edge of the building.

2. Upstream flat roofs
For large flat roofs, the height of the discharge device may be reduced by two conditions formulated in Chapter 6.2.1.2.3. In order to avoid discontinuity at the edge, P&K KFA offers the possibility of also taking these conditions into account for the starting height of the recirculation zone at the edge of the building. Since equation 8 and the double building height refer to the height of the discharge device, both heights are reduced by the value HÜ. To this extent, the recirculation zone lies beneath the discharge device.

Two checkboxes under Inputs/Parameters offer the option of selecting the favoured procedure:

  • Upstream flat roofs in accordance with the guideline (on) or deviating (off)
  • Upstream ridge roofs in accordance with the guideline (on) or deviating (off)

The default is the option that complies with the guideline.

Note: The expert mode can be activated under Preferences.