Schwedische Vorschrift 2009 (Englisch)
The Swedish codes 2009 actually represent an evolution of “Ljud från vindkraftverk”, Naturvårdsverket. The latest available version is from April 2010, but the latest modifications are at the time of writing only available from Naturvårdsverkets homepage http://www.naturvardsverket.se/Stod-i-miljoarbetet/Vagledning-amnesvis/Buller/Buller-fran-vindkraft/buller-vindkraft-riktvarden/
This latest version, for ease called Swedish 2009 as the 2009 edition provided some of the most important changes, is generally based on the original “Ljud från vindkraftverk” with the following modifications:
- a. Roughness correction of source noise level has been removed and replaced by the standard 0,05 m wind profile
- b. Revised code for offshore calculations
- c. Option of comparing with ambient noise (masking)
- d. Allowing for Nord2000 calculations
The elimination of the roughness correction greatly simplifies the calculation. Instead of modifying the wind speed at hub height based on a roughness specific wind profile, all calculations now assume a standard IEC profile of 0,05 m, which is used by basically all other national codes. This means that the noise figure in the wind turbine catalogue of windPRO can be used directly without modification. Therefore the selection of roughness length has been removed. This affects both onshore and offshore calculations.
The offshore calculation calculates similar to an onshore calculation out to 1000m from the turbine. From then a revised version of the 2002 code with different dampings are used. The noise is calculated at landfall and from then uses the land code to the dwellings. The formula in the current form is at the time of writing only available from here: http://www.naturvardsverket.se/upload/stod-i-miljoarbetet/vagledning/buller/buller-vindkraft/matning-berakning-vindkraftljud.pdf
In windPRO DECIBEL select Swedish 2009 and select Offshore wind farm. If that option is checked, click the button Edit water areas to select an area object defining the sea. Any purpose of the area object will do. Any location outside the selected area type is considered on land and the boundary of the area marks the coastline.
Masking of noise
From the 2009 version of “Ljud från vindkraftverk” it is possible to compare with masking from ambient noise. Depending on type of surroundings it is possible from table values to estimate the ambient noise at a dwelling. If the difference between ambient noise and calculated noise from turbines is sufficiently small the noise impact at the receptor can be disregarded. The masking element has in general not been implemented in windPRO but it is possible to enter ambient noise in the noise receptor object.
From 2009 the Swedish code allows the use of NORD2000 as an alternative method. NORD2000 is not part of the DECIBEL module, but a module on its own.
Swedish Low frequency noise
The Swedish guideline for low frequency noise as it is described by Naturvårdsverket cannot be calculated with DECIBEL. Instead NORD2000 in windPRO can be used to calculate low frequency noise.