High Court orders turbine to shut down at certain windspeeds overnight due to sleep disturbance 

The High Court has ordered that a wind turbine in Co Wexford be shut down at night for certain windspeeds due to its potential to disturb sleep.

The turbine will also have to operate on a lower mode during quiet waking hours at certain windspeeds.

Last year, the High Court ruled that one of two wind turbines at Ballyduff Windfarm at Kilcomb, near Enniscorthy, Co Wexford, amounted to an “unreasonable interference” with the enjoyment of two couples’ properties.

This action was taken by Margret Webster and her partner Keith Rollo, whose home is close to the wind farm that has been operational since 2017.

A second action was taken by Ross Shorten and Joan Carty, who owned another property close to the turbines but sold it after commencing their proceedings in 2018.

The wind farm is operated by Meenacloghspar (Wind) Limited.

The cases were the first private nuisance claims from wind turbine noise to run in Ireland or the UK, the judge said.

At the conclusion of module 1 of the trial last year, the High Court deemed that “one of the two turbines caused a nuisance to the plaintiffs during night hours and quiet waking hours”.

The judge, Ms. Justice Emily Egan, then directed the parties involves to “attempt to agree appropriate mitigation measures to abate the nuisance in advance of module 2”.

The Court noted that the defendant trialled just one potential mitigation measure – the operation of the turbine in a lower power mode.

This reduces the rotational speed of the turbine blades and marginally reduces the wind turbine noise.

The plaintiffs said this lower power mode did not mitigate the noise nuisance and sought an order to shutdown the turbine during “sensitive”, quiet waking hours.

The judge agreed that the lower power mode trialled by the defendant “does not ameliorate the nuisance”.

However, the defendant’s claimed that the wind turbine noise did not create a noise nuisance even in its “full” power mode and that no mitigation is required.

The defendant also sought to bring forth new evidence to persuade the Court to review the findings made last year after module 1 of the trial.

It was contended by the defendant that the new evidence showed that the wind turbine noise was lower than the limit currently fixed in Irish planning guidance.

The judge rejected the data provided by the defendant and said it did not provides a “scientifically robust guidance on what level and nature of wind turbine noise causes unacceptable interference with residential amenity”.

She added that the new evidence “does not comprise a useful or complete baseline assessment for the purposes of crafting abatement measures”.

“Even if admitted, the defendant’s new evidence would not substantially impact or alter my finding on liability”, said the judge, who declined to admit the evidence or revisit last year’s findings on liability.

The judge remarked on the benefits of renewable energy but added that the plaintiffs are “entitled to an injunctive remedy”.

The Court ordered that the It seems that noise levels therefore had to be reduced by a “clearly noticeable degree”.

She remarked that five decibel reduction would be an “easily noticeable noise differential”.

The defendant was ordered to implement this noise reduction and to operate on a lower mode “during quiet waking hours at certain wind speeds and wind directions”.

The judge added however that this would not be an acceptable solution during night hours.

The judge said this is partly because she is “not satisfied” that the predicted noise level reductions by lowering the power mode “can be reliably and consistently achieved at night”.

She also noted that “constant sudden changes to the wind turbine noise at night would have a jarring effect, disturb sleep and thus cause ongoing nuisance”.

As a result, the judge ordered the shutdown of the turbine at night for “windspeeds of 5m/s to 11 m/s inclusive in those wind directions associated with high AM values and thump AM”.

AM (Amplitude Modulation) relates to the variance of wind turbine noise, which can cause more annoyance than constant, stable noise of a similar level.

A “high AM value” is a noticeable variation in the sound, often described as a “swish” or a “thump”.