Draft National Wind Farm Development Guidelines - July 2010

A developer should provide a list of annual duration of shadow flicker at any affected
receptor, along with a map showing the annual number of shadow flicker hours at all
locations within the zone of influence. Any subsequent development will then be required
to take this information into consideration in their assessment. The combined impact of all
developments should not exceed the recommended limits. In the case where new
receptors are created between one development and the next, the impact of the first
development(s) on these should be determined from the map provided.
At the time of submission, the application should consider cumulative impacts only from
approved developments (including micro-siting where this is complete and submitted) and
existing wind farms. As the development progresses (say from approval to a micro-sited
layout), it must consider any changes (formally submitted) to the suite of approved and
existing developments, including any new developments that have subsequently been
submitted.
In effect, this defines a maximum shadow flicker time (initially 30 hr/yr) at each residence.
When a Development Application is submitted, or resubmitted, to a planning authority, the
duration of shadow flicker at each residence is reported. This is registered and subtracted
from the maximum shadow flicker time. Subsequent applications will have less ‘available’
shadow flicker time. If there is insufficient ‘available’ shadow flicker time, then an
application wishing to submit an application or change from its current status is responsible
for mitigation of any negative impacts.
E.6 Glossary & acronyms
Intensity The contrast in lighting between alternating shadow and no shadow. When the
Sun is (temporarily) fully obscured by a turbine blade, lighting will vary from full sun to full
shade. When the Sun is (temporarily) partially obscured by a turbine blade, lighting will vary
from full sun to partial shade. The proportion of the Sun that is obscured by the blade is
defined as the intensity.
Blade chord The distance from the trailing edge of the blade to the leading edge of the
blade, typically the longest dimension of the blade cross-section.
Receptor The location, in three dimensional space, at which measurement of shadow
flicker is of interest. In these guidelines, the receptor generally corresponds to a dwelling.
Developer The party who owns the wind farm or the wind farm application.
Impact A potential negative effect of shadow flicker.
Measure The metric (with units) used to quantify an impact.
Micro-siting Small adjustments to turbine position (typically less than 100m) subsequent to
planning approval but prior to construction, usually to account for practical factors
affecting constructability.
Exposure The quantity of an impact at a receptor.
Level The allowable exposure.
Consequence The severity of an impact (quantified as ‘trivial, some nuisance value’,
‘minor, possibility of injury’, ‘major, possibility of fatality’, ‘major, . possible multiple
fatalities’).
Likelihood The probability of an impact occurring (quantified as ‘extremely rare,