Expert Report · Mandatory under BImSchG · TA Laerm

Acoustic Emission Prognosis for Wind Turbines

Standard: DIN ISO 9613-2 · Assessment basis: TA Laerm

The acoustic emission prognosis (Schallimmissionsprognose) calculates how loud the planned turbines will be at the nearest residential buildings — predictively, before construction. It is the mandatory noise calculation for every BImSchG permitting procedure and the basis for assessment under the TA Laerm (Technical Instructions on Noise).

What does it contain?

Source data of the turbines: sound power level L_WA in dB(A) from manufacturer measurements per FGW TR 1 / IEC 61400-11, incl. octave spectrum and ±2σ safety margin
Immission points: location and protection status of all relevant residential buildings (general residential area, mixed-use area, village area, etc.)
Propagation calculation per DIN ISO 9613-2 (alternative point-source models of the LAI), accounting for reflection, ground absorption, and weather
Level summation for multiple WTGs and pre-existing noise from other sources
Comparison with TA Laerm thresholds day/night
If thresholds are exceeded: proposed mitigation measures (noise-reduced night mode)

Sound propagation from a wind turbine: noise levels in dB(A) at 300 m, 500 m, 750 m and 1,000 m distance with TA Laerm thresholds

Schematic sound propagation from a WTG — immission levels by distance (guideline values)

Sound power levels compared (guideline values)

Turbine class	L_WA full load	Night mode (typical)
2 MW turbines (legacy)	103–105 dB(A)	99–101 dB(A)
3–4 MW class	104–107 dB(A)	100–103 dB(A)
5–7 MW class	105–109 dB(A)	101–105 dB(A)
Modern low-wind turbines with "quiet mode"	104–106 dB(A)	96–100 dB(A)

What does an acoustic emission prognosis cost?

Guideline value EUR 5,000 – 20,000 for a wind farm with 3–6 turbines. For high complexity (many immission points, high pre-existing noise, development of a mitigation concept) up to EUR 25,000. For repowering projects, the effort is often lower because the geometry of the existing turbines is similar.

Who may prepare the report?

Only measurement bodies accredited under § 29b BImSchG or accredited acoustics engineering firms (DIN EN ISO/IEC 17025). Established providers in the onshore WTG sector include: Deutsche WindGuard, TUeV Sued, ITAP, Woelfel, KOETTER, Mueller-BBM and various regional acoustics offices.

Acoustic emission prognosis for your wind farm

We forward your enquiry to an accredited acoustics engineering firm and obtain a quotation — tailored to turbine count, site, and permitting stage.

Request a quote

Frequently asked questions

What is the difference to a sound protection report?

The sound protection report is the extended document that, in addition to the prognosis, describes a concrete mitigation concept (measures, proof of effectiveness). In practice, both are often delivered in the same document.

How accurate are the prognoses?

Very accurate — real-world measurements typically come in 0.5–2 dB below the prognosis because the model calculates conservatively. Authorities accept DIN ISO 9613-2 without dispute.

What about infrasound?

Infrasound is not covered by standard prognoses under TA Laerm (frequency range > 16 Hz). For low-frequency components (8–100 Hz) there are special reports per DIN 45680, which are rarely required in practice.