Commercial and industrial areas shall be planned in a way that the compatibility with adjacent, noise-sensitive areas as required in § 50 of the Federal Immission Control Act is guaranteed by applying § 1 para. 4 of the Federal Land Utilisation Ordinance laying down the possibilities to structure building areas. The "zoning" mentioned in § 50 does not only refer to noise protection clearances but also to measures influencing the locational relation between emitting and affected use in a positive way. In this context the designation possibilities of § 9 para. 1 No. 24 of the Federal Building Code become important. We also would like to point to the shielding effect of high and seamless development on the margins of building areas.

The structuring of commercial areas should therefore be oriented by the principles of optimum noise protection clearances to noise-intensive installations, by the existing measures of shielding and by the principle of noise concentration. The essential principle "noise to noise" leads to a preferably compact arrangement of noise-emitting uses, which can be shielded with less effort than scattered and dispersed operating plants. (But this is exactly what is often required from the structural and urban climatic point of view (aeration)).
 

Sound allocation in commercial areas (§ 1 para. 4 sentence 1 No. 2 of the Federal Land Utilisation Ordinance) 

Immission-oriented and area-related sound power levels (PWL) are defined for a commercial area, which is divided into noise zones, in order to guarantee the adherence to the immission guide values within TA Lärm (Technical Instructions on Noise) at the relevant places of immission inside or outside the plan area.

Undisturbed and loss-free propagation to all sides above the ground into the upper half space (Ds = 2ðr²), i.e. without considering aeration, additional attenuation through the ground and meteorological conditions, directivity, barriers and reflections, is the basis for determining the PWL.
Only those installations and firms are permitted in the individual noise zones (LB, Lärmbereich) of a commercial area whose sound emissions do not exceed the following PWL per m²:

The requirements are considered as fulfilled if the sound power level (L_WA) of an installation or firm does not exceed the permitted sound power level (L_WA,zul) of the installation site/company site. The permitted sound power level is calculated as follows:

L_WA,zul = [IFSF + 10 lg F] dB(A)
with F = area of the total installation site/company site in m²

The requirements are considered as fulfilled if the rating level of the operational noise of an installation or firm (assessed pursuant to TA Lärm) does not exceed the immission allocation (IK, Immissionskontingent) granted for the installation site/company site. The immission allocation is calculated as follows:

IK = [L_WA,zul - 20 lg s - 8] dB(A)
with s = distance from the centre of the installation site/company site to the relevant place of immission in the sphere of influence (Nos. 2.2 and 2.3 of TA Lärm) in m

In the context of partly or completely developed areas, area-related sound power levels are only used as for major alterations or new installations.