Draft National Wind Farm Development Guidelines - July 2010

• The use of recreational facilities by any given individual is typically sporadic and
infrequent, it is very unlikely that the annual exposure of shadow flicker they
experience would come close to the limits designed for residents
• The impact (annoyance) would be relatively minor
Distraction of vehicle drivers
There is a negligible risk associated with distraction of vehicle drivers who experience
shadow flicker, for the following reasons:
• Shadow flicker is little different for a vehicle in motion than the effect of shadows from
trees on the side of the road or high passing vehicles, neither of which represent a
significant risk in terms of road transport.
• In spite of extensive searches, no references to motor vehicle accidents caused by
this phenomenon have been found
It is noted, however, that until wind farms become widespread in Australia they will
represent a novelty that could cause distraction for drivers (regardless of shadow flicker).
Consideration should be given to development of viewing areas for wind farms close to
high volume roads.
Initiation of epileptic seizures
There is a negligible risk of epileptic seizures being caused by conventional horizontal axis
wind turbines, for the following reasons:
• Less than 0.5% of the population are subject to epilepsy at any one time, and of
these, approximately 5% are susceptible to strobing light (Epilepsy Action Australia,
2009).
• Most commonly (96% of the time), those that are susceptible to strobe lighting are
affected by frequencies in excess of 8 Hz and the remainder are affected by
frequencies in excess of 2.5 Hz. Conventional horizontal axis wind turbines cause
shadow flicker at frequencies of around 1 Hz or less.
• Alignment of three or more conventional horizontal axis wind turbines could cause
shadow flicker frequencies in excess of 2.5 Hz; however, this would require a
particularly unlikely turbine configuration.
To summarise, the chance of conventional horizontal axis wind turbines causing an
epileptic seizure for an individual experiencing shadow flicker is less than 1 in 10 million.
There is a possibility that the risk is higher for some types of non-conventional turbine;
however, such turbines are outside the scope of these Guidelines and should be
considered on an individual basis. For the purposes of these Guidelines, a nonconventional
turbine can be considered as one that causes a shadow flicker frequency of
2.5 Hz or greater. This effectively aligns these guidelines with BERR (2008), which
acknowledges the low risk associated with this issue but nevertheless includes a
requirement that the turbine frequency be les than 2.5 Hz.
E.2.3
Related documents and standards
Australian
At the time or writing, planning regulations typically note shadow flicker as an issue that
must be addressed but only two examples provide guidance on how this should be done.
These are the Victorian guidelines (SEAV, 2003), which specify a limit of 30 hr/yr for shadow
flicker, and the South Australian development plan (Department of Planning and Local
Government, August 2002) which suggest that shadows only need be considered out to a
distance of 500 m. Victorian Department of Planning and Community Development also
provides model planning permit conditions which indicate that application of 30hr/year
does not apply to dwellings on the wind farm site; however, this condition is not applied
directly in the guidelines.
Draft National Wind Farm Development Guidelines – 2 July 2010 Page 149