Environmental Impact Assessment

Environmental Impact AssessmentAs a part of an environmental impact assessment, it is important to analyse the potential impact of the planned wind turbine park on each individual neighbour.

The approval of a wind park might be delayed due to local opposition, often caused by simple lack of information supplied to the neighbours of the coming project. This can easily lead to unfounded or exaggerated fear of the impact the wind park will have.

The environmental impact of the wind farm is calculated with the program windPRO. For noise calculation, several types of models can be applied depending on the country/local demands.

The results will be presented in a report including the following details for each neighbour:

  1. Noise impact caused by the wind park based on a certain calculation standard.
  2. Number of shadow flickering hours during a year and on “the worst day”.
  3. Number of wind turbines visible from the house.
  4. Photomontage showing the wind park seen from the house.

The results of the calculation are listed and compared against the legislation and demands (if in force) of the local government/community, and a simple explanation of the various nuisances the neighbour may suffer are given.

The neighbour can, thus, get an overview of the project and of its impact on his/her premises. This is an ideal way of informing the neighbours of a project of how they may be affected individually.


EMD has a long and robust experience in assessing the environmental impact of wind turbines.

Noise impact assessments are done using the DECIBEL module of our windPRO software, applying settings relevant to the specific national codes or standards. The analyses include traditional noise regulations as well as the option of low-frequency noise estimations. Even more advanced noise calculations and scenarios can be analyzed and modelled using the dedicated NORD2000 model.

In the case of any nearby existing turbines, these should be added in order to model the cumulative impact. Any neighbours, dwellings or other points of interest (POI’s) can be identified from topographic maps of the area, but, for higher accuracy, the POI’s should be surveyed by a charted surveyor. The local authorities could be consulted in order to determine the classification of sensitivity to noise impact for each individual POI.

Typical deliverables from these calculations are reports of noise impact at the position of the individual POI’s as well as noise maps (noise contour isolines or rasters).

Shadow Flickering

The flickering of the turbine rotor’s shadow is a serious and often underestimated nuisance to neighbours of a wind farm.

EMD can assess and document the shadow flickering impact in terms of hours per year during which a neighbour or an area would be affected by this issue. Also, the maximum duration per day is calculated. Both can be estimated for the worst case (no clouds, WTG always rotating and wind direction “worst case”) or for a statistically expected scenario, based on assumptions on monthly sunshine probability and operating hours of the turbines.

The assessment takes into account the visibility of the turbines and of the sun, as dictated by local terrain conditions and obstacles.

Calculations can be made either for a set of shadow receptors (e.g. windows of a house) or for a user-defined area. Results are presented in the form of calendars of cumulated hours with flicker or – for the area calculation – as isolines of flickering hours.

If the wind turbines exceed the allowed shadow flickering, the calendar can be used to plan the operation of the turbines to eliminate the problem. The cumulative number of curtailment hours can then be used to estimate the relevant production losses.

Visual Impact

The visibility of a wind farm represents a major hindrance to its acceptance by the public and authorizing institutions in many countries.

EMD can assess and document the optical or radar visibility of WTGs from any point in the landscape. The cumulative visual impact of multiple wind farms can also be calculated, as well as a map of non-visibility of WTGs by radars.

The assessment considers the visibility of the turbines as dictated by local terrain conditions and obstacles, such as forests or buildings.


The static visualization of a wind park project – a photomontage – typically includes the following two distinct steps.

First, a site inspection is conducted, during which photos are taken of the development area. The observer positions (photo standpoints) are either determined by the local authorities, such as the community or municipality, or simply chosen from a screening analysis to be as representative as possible, in order to make the landscape in the picture clearly recognizable to the local inhabitants or the authorizing institutions.

Secondly, desk work implements extensive use of the software windPRO, which includes a full-scale feature to calibrate the photos and a catalogue of the visual details of over 800 wind turbines. These facilities will be used to generate a static (or, if needed, an animated) photomontage. This could be done in a variety of ambient daylight conditions, such as bright, normal and reduced visibility conditions. For night conditions, a rendering of the aviation obstruction lights can be performed.

Lastly, EMD can even generate a 3D animation of your proposed layout, complete with a virtual “fly through” of the farm. This can be helpful in allowing landowners or local councils/governments to visualize what the project will be like when it is realized.