CNOSSOS-EU
Calculation acc. to ...
The calculations can be performed according to:
Note
Projects created with CadnaA 2021 MR2 or earlier are opened with calculation method „2015/996 EU without 17534-4 2020“ 17534-4-20. This option is only available when opening earlier projects and ensures a recalculation with the same results.
Lateral Diffraction
Two options are available:
- none: No lateral diffraction considered.
- Point Sources: Lateral diffraction is considered at point sources, but not at line and area sources.
if Distance smaller (m)
This setting defines the distance between source and receiver for which lateral diffraction is taken into account. The default value is 1000 m.
Obstacles within Area Source do not Shield
see ISO 9613 (1996)
Sources in Building/Cylinder do not shield
see ISO 9613 (1996)
Temperature / rel. Humidity
The air attenuation is calculated based on the temperature and the relative humidity according to ISO 9613-1. Intermediate frequency values result from linear interpolation. The temperature specified serves also as the ambient temperature when calculating the exhaust stack’s directivity.
Note
The octave band at center frequency of 31.5 Hz is excluded explicitly from the CNOSSOS-EU calculation model.
Additional Information
Ground Absorption in Source-Region
As an alternative to the calculation of the ground attenuation based on the default ground absorption (see Ground Absorption Tab) and the „ground absorption“ objects (see Ground Absorption Areas), the ground absorption Gs in the source region can alternatively be specified by a string variable CNOSSOS_GS in each source. If present, this value is used (e.g., CNOSSOS_GS = 0.7).