Shadow flicker is the name given to a phenomenon caused when the sun is behind the turbine blades as it rises or sets, casting a moving shadow over a small opening in a building such as a window, creating a flickering effect within the building.
The ‘Wind Energy Development Guidelines for Planning Authorities’ (Department of the Environment, Heritage and Local Government, 2006) set out limits for the control of shadow flicker from wind energy developments to prevent any nuisance and to prevent any impacts on health. Current guidance limits allow shadow flicker to 30 minutes per day for a maximum of 30 hours per year. The Lyre Wind Farm has been designed to utilise advancements in turbine technology to ensure that the effect of shadow flicker is eliminated and will not affect any inhabited properties.
The Department of Housing, Planning and Local Government (DHPLG) published “Draft Revised Wind Energy Development Guidelines” in December 2019 and these draft guidelines were under public consultation until 19th February 2020. The draft guidelines take account of a previous “Targeted Review” consultation undertaken in by the DHPLG 2013 and subsequent detailed engagement between the relevant Government Departments culminating in a “Preferred Draft Approach” , which was announced in June 2017 to inform and advance the conclusion of the review.
The design of the proposed development at Lyrenacarriga has taken account of the 2017 “Preferred Draft Approach” and has also taken account of the provisions of the 2019 “Draft Revised Wind Energy Development Guidelines”. At time of writing, the 2019 Draft Revised Wind Energy Development Guidelines are not yet in force may be subject to further change on foot of completion of the public consultation process, so the relevant guidelines remain those published in 2006.
Should the revised Wind Energy Development Guidelines be finalised in advance of a planning decision being made on the proposed development, with current shadow flicker thresholds being amended, if necessary, the proposed development can comply with any revised shadow flicker requirements by implementing mitigation by design (as detailed in the EIAR) through turbine selection and use of the flexible built-in turbine control systems.