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Generate Radiating Building

The command Generate Building from the context menu can be applied to model a building whose outer walls and the roof are sound radiating.

Entering an Area Source

  • Enter a horizontal area source forming the building’s base.
  • Activate the option „Trans.Loss" on the edit window of the area source.
  • Enter an interior sound pressure level of 100 dB(A) and a transmission loss (weighted sound reduction index) of 30 dB.

Area Source: Emission based on interior level and transmission loss

Generate Building

  • Click on the border of the area source with the right mouse button and select the command Generate Building from the context menu.

Command Generate Building from the context building

  • On the dialog Generate Building enter a height of 8 m and close the dialog by OK.

Note

In addition, the absolute ground height at the houses base and the absorption coefficient can be entered, either as a single number rating or as a referenced spectrum.

Upon closing the dialog by OK CadnaA generates:

  1. a building of the specified height - in this example - of 8 m height,

  2. die respective numbers of vertical area sources for each facade and

  3. a horizontal area source as radiating roof.

The emission relevant parameters for each subsequent source are taken from the first area source entered. The vertical area sources representing the walls are generated at a distance of 0.05 m in front of the building. The horizontal area source representing the roof is generated at the entered building height.

The directivity index K0 for the vertical area sources (i.e. radiating facades) is set automatically to 3 dB, while for the horizontal area source (i.e. radiating roof) no directivity index is taken into account (K0 = 0 dB).

Generate Building: building with 6 corners

Changing Sequence of Layers

On the plan view, the area source representing the roof’s radiation is hidden by the building’s polygon. To change this, open the dialog Layer on the Options menu. The ranking of objects on this dialog determines the sequence when CadnaA draws objects onto the screen. The object being at the top end of the list is drawn first, the one at the bottom is drawn last. So, the building has to be ranked at a higher position in the list of layers than the area source.

  • Open the dialog Layer.
  • Click on „Area Source“ in layer list and keep the left mouse button pressed.
  • Drag with the mouse the „Area Source“ downwards in the list, below the „Building“ and release the mouse button.

Dialog Layer: Dragging the „Areas Source“below the „Building“

  • Click on button „Apply“ and move the dialog apart to see the result more easily.
  • The area source - shown with a hatching - is no drawn above (i.e. after) the building has been drawn.