Shadow flicker

Under certain conditions, moving shadows cast by wind turbine blades can pass over windows in a building. To people within that building, those shadows can appear to flick on and off; this effect is known as ‘shadow flicker’. The moving shadows can also be seen passing across the ground, which can be considered as ‘shadow throw’.

Whilst it is possible to predict periods when shadow flicker could theoretically occur using industry standard software packages, there are no guidelines in the United Kingdom to quantify what levels (if any) are acceptable.

TNEI has experience of conducting shadow flicker assessments for urban and rural wind energy sites across the UK. Our technical consultants use Windfarm, the industry standard software, to assess the potential for shadow flicker and have assessed sites ranging from single turbine developments to multi-turbine wind farms.

The team undertakes assessments for developers and for local Planning Authorities to minimise shadow flicker through good site design, without unduly restricting site capacity. For sites where shadow flicker is anticipated, we can also draft suitable planning conditions and protocols which can be adopted to protect local residents against the impacts of shadow flicker.

TNEI has a good knowledge of technical mitigation measures available and can advise on appropriate planning conditions. We can also provide detailed analysis of potential periods of downtime resulting from shadow flicker management, an essential tool for accurate project revenue calculations.

Our team of specialists also undertake shadow flicker complaint investigations and use our specialist software to identify which turbines are causing the shadow flicker and advise how the impacts can be mitigated. In addition to our desk based assessment work, we can also arrange for specialist monitoring equipment to be deployed to measure the levels of shadow flicker at individual receptor locations and to verify the success of any mitigation measures that are adopted.

If you have any shadow flicker requirements for your project or you have a complaint, contact us to find out how we can help you.