Draft National Wind Farm Development Guidelines - July 2010

as the actual limit, rather than the conservative limit. As described above, most
regulations, including the German regulations, have eliminated this ‘loop-hole’ by
specifying limits for actual and modelled.
As with international approaches, it is still desirable to allow proponents a mitigation
strategy for receptors where modelling shows more than 30 hr/yr. Mitigation may either be
via scheduling or an approved calculation method to account for clouds. In this case, a
lower threshold should apply. 10 hr/yr is recommended as the threshold. Although this is
slightly higher than the German limit, it is consistent with a number of other jurisdictions and,
reflects the less conservative approach of current Australian practices.
Vegetation, topography and development can block shadows at certain locations
Vegetation, topography and other developments (buildings, factories, etc.) that block
sunlight at times when shadow flicker occurs effectively eliminate that shadow flicker. In
Effects of topography (page 161) it is recommended that topography be included as part
of the modelling; however, vegetation and development are not, by default included.
These obstructions may be included on a case-by-case basis as a means to mitigate
shadow flicker. However, it is not straightforward to include such obstructions in
commercial models, and extracting the relevant details from the model to do the
calculations externally is also difficult and time-consuming.
To maintain transparency and simplicity, it is recommended that this approach only be
allowed where the obstruction completely blocks the view, from the receptor, of a turbine
that is contributing to shadow flicker (photomontages or other means should be provided
to demonstrate this). In this case all hours of shadow flicker attributable to that turbine may
be discounted.
Draft National Wind Farm Development Guidelines – 2 July 2010 Page 163