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You are here: BAILII >> Databases >> High Court of Ireland Decisions >> Webster & Anor v Meenacloghspar [Wind] Ltd; Shorten & Anor v Meenacloghspar [Wind] Ltd [No.2] (Approved) [2025] IEHC 300 (27 May 2025)
URL: http://www.bailii.org/ie/cases/IEHC/2025/2025IEHC300.html
Cite as: [2025] IEHC 300

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THE HIGH COURT

                                                                                                                         [2025] IEHC 300

     Record Number: 2018 8457P

BETWEEN:

MARGARET WEBSTER AND KEITH ROLLO

                                                                                                                              PLAINTIFFS

AND

 

MEENACLOGHSPAR (WIND) LIMITED

                                                                                                                           DEFENDANTS

 

AND

                                                                                                  

         Record Number: 2018 8458 P

BETWEEN:

ROSS SHORTEN AND JOAN CARTY

                                                                                                                              PLAINTIFFS

AND

 

MEENACLOGHSPAR (WIND) LIMITED

   DEFENDANTS                     

JUDGMENT of Ms. Justice Emily Egan delivered on the 27th day of May, 2025

INDEX

Summary of judgment. 3

Issues arising for determination at module 2. 3

The delineation of the evidence for module 2. 6

Background chronology. 6

Nature of the disputed new evidence. 7

Legal principles regarding the admissibility of new evidence and the re-opening of a court's prior judgment. 9

Application of legal principles in relation to the admissibility of new evidence. 10

Does the new technical specification published by the International Electrotechnical Commission provide a justification for the introduction of the disputed new evidence? 11

Justification advanced in Mr. Carr's report 11

The IEC does not meet the lacuna identified in para. 375. 11

The IEC is not the disputed new evidence. 11

Alternative justification advanced by the defendant in oral legal submissions: substantial differences between the IOA RM analysis and the IEC AM analysis. 13

Conclusion on criterion 1 of Murphy v. Minister for Defence. 14

Is the disputed new evidence admissible qua baseline assessment?. 14

The disputed new evidence would not substantially impact or alter my finding on liability. 16

The IOA RM analysis of the 2017 NF data supports, rather than undermines this court's finding on AM values in the principal judgment 16

The disputed new evidence does not undermine this court's finding on low frequency noise and thump AM   16

The disputed new evidence does not undermine this court's finding on dominance. 17

The defendant's reliance on a combination of WEDG 2006, the IEC and the Phase 2 penalty scheme is misplaced  17

Argument inconsistent with the defendant's position at module 1. 17

Lacuna: WEDG 2006 does not address thump AM.. 17

WEDG 2006 was not drafted with nuisance in mind. 17

WEDG 2006 was not drafted with AM in mind. 18

WEDG 2006 is under review and takes no account of low frequency WTN. 18

WEDG 2006 takes no account of night time background noise levels. 18

S. 28 is not the yardstick of nuisance. 19

WEDG 2006 does not address most of the Defra criteria. 20

The Phase 2 penalty scheme is under review.. 20

The IEC does not apply the Phase 2 penalty scheme. 20

Plaintiffs' further argument: the Carr comparative exercise misapplies the Phase 2 penalty scheme  21

Conclusion in relation to the disputed new evidence and in relation to the application to re-visit the principal judgment. 22

Plaintiffs' evidence. 23

Evidence of Ms. Webster 23

Evidence of Mr. Stigwood, plaintiffs' acoustician. 26

Misinterpretation of the principal judgment 26

Has the 1,600 mode abated the nuisance?. 26

The IEC. 28

Other evidence from Mr Stigwood relevant to the potential abatement orders this court might make  28

Evidence of Mr. Mayer, Mechanical and Automotive engineer 29

Defendant's evidence. 29

Evidence of Mr. Brazil 29

Evidence of Mr. Carr, defendant's acoustician. 29

Figure 5: IOA RM results - 2024 1,600 rear garden 24 hour data. 30

Figure 6: IOA RM results - 2024 1,600 mode rear garden night-time (23:00 to 07:00hrs) data  31

Table 3:  2024 1,600 mode rear garden 23:00 to 04:00hrs data- downwind only. 31

Has the 1,600 mode abated the nuisance? Onus of proof 33

Findings of fact regarding the 1,600 mode. 33

Analysis and findings of fact relevant to the potential abatement orders this court might make  34

Are the plaintiffs entitled to an injunction?. 38

Relevance of the public interest. 40

Crafting the injunction. 41

Windspeeds of  5 m/s to 7m/s inclusive. 43

Windspeeds of  8 m/s. 44

Windspeeds of  9 m/s. 44

Windspeeds of 10 m/s and 11 m/s. 44

Windspeeds of  12 m/s and above. 45

Conclusion. 45

 

Summary of judgment

At the conclusion of Module 1 of this trial, I held that one of the two turbines operated by the defendant ("T2"), caused a nuisance to the plaintiffs during night hours and quiet waking hours ("sensitive periods"). I directed the parties to attempt to agree appropriate mitigation measures to abate the nuisance in advance of module 2. The defendant trialled just one potential mitigation measure: it operated T2 in a lower power mode. This reduces the rotational speed of the turbine blades and marginally reduces WTN.

 

The plaintiffs maintain that this lower power mode has not abated the nuisance and seek an order directing the shutdown of T2 during sensitive periods. The defendant's principal argument is that the WTN does not pose a nuisance even in its "full" power mode and that no mitigation is therefore required. 

 

The defendant sought to adduce new evidence to persuade the court to revisit the finding on liability made at module 1. This new evidence comprises an analysis of the raw noise monitoring data presented to the court by the plaintiffs in the course of module 1. The defendant contends that this shows that, even allowing for amplitude modulation ("AM"), [1] the WTN levels are lower than the noise limit fixed by current Irish planning guidance on wind energy developments (WEDG 2006).

 

I have determined that this new evidence could with reasonable diligence have been obtained for use at module 1. I reject the defendant's argument that a new technical specification on noise measurement techniques provides scientifically robust guidance on what level and nature of WTN causes unacceptable interference with residential amenity. I also conclude that the defendant's new evidence does not comprise a useful or complete baseline assessment for the purposes of crafting abatement measures. I further find that, even if admitted, the defendant's new evidence would not substantially impact or alter my finding on liability. I therefore decline to admit this evidence or to revisit my finding on liability. 

As such, I have not found it necessary to decide whether the plaintiffs are correct in their argument that the new evidence does not in fact show that night time WTN levels are within the noise limits fixed by WEDG 2006, as contended by the defendant. 

 

After reviewing the evidence I find as a fact, on the balance of probabilities, that the lower power mode trialled by the defendant does not ameliorate the nuisance. Applying the principles set out in Shelfer v. City of London Electric Company, I hold that the plaintiffs are entitled to an injunctive remedy.

 

Renewable energy is of benefit to the public, which is of relevance in crafting an injunctive remedy. Therefore, if I can be satisfied that measures short of the complete shutdown of T2 during sensitive periods would abate the nuisance, it is appropriate to fashion a remedy accordingly.

 

I then consider what form of injunction is just in all the circumstances of the case. It seems that the only potential way to abate the nuisance is to reduce noise levels (at relevant windspeeds/wind directions) by a clearly noticeable degree. A 5dB reduction or increase is thought to be an easily noticeable noise differential.  However, to simply order a 5 dB reduction in the WTN would require further extended monitoring and ongoing court supervision. It would also lead to further dispute and continuing  nuisance. I therefore prefer to proceed by restricting the operation mode of T2 provided this can, when necessary, reliably and consistently reduce WTN by 5dB.

 

I am satisfied that it is reasonable to restrict T2 to certain lower operating modes during quiet waking hours at certain wind speeds and wind directions. However, this would not be an acceptable solution during night hours. This is partly because I am not satisfied that the noise level reductions which are predicted to occur by altering the power mode of the turbine can be reliably and consistently achieved at night. It is also because constant sudden changes to the WTN at night, as the wind rises and falls, would have a jarring effect, disturb sleep and thus cause ongoing nuisance. I therefore order the shut down of T2 at night for windspeeds of 5m/s to 11 m/s inclusive in those wind directions associated with high AM values and thump AM.

Issues arising for determination at module 2

1. On 14th July 2022, O'Moore J. directed a modular trial of this nuisance action. Module 1 was to determine the issue of liability for nuisance. If required, module 2 would then determine the appropriate remedy and quantum of damages for nuisance.


2.  The trial of Module 1 concluded on 6th November 2023. By judgment of 8th March 2024 ("the principal judgment"), I held that one of the two turbines operated by the defendant ("T2"), caused a nuisance to the plaintiffs during night hours and quiet waking hours ("sensitive periods"). Although a "narrow judgment call", I decided that the wind turbine noise ("WTN") could be tolerated during other times.

3. I was satisfied that, on the majority of the audio recordings, the WTN is the only noise that one can consistently hear. It was also clear from the audio recordings that the WTN displayed the particular intrusive characteristics complained of by the plaintiffs such as "erraticism, impulsivity, excessive AM values and thump AM". [2] I was also satisfied that the clear and unavoidable conclusion from the audio recordings taken by the plaintiffs' experts was that their external and internal soundscape was dominated by the WTN. In all likelihood, this dominance arose from a combination of the level of exceedance of the WTN over background noise levels, its high AM values, its comparatively low spectral frequency and its other attention drawing characteristics. [3]

4. I found that two features in particular contributed towards this dominance rendering the WTN an unreasonable interference: first, frequent and sustained periods of AM values widely acknowledged to be associated with high levels of annoyance and second, thump AM which, together with its associated vibration, was the most intrusive quality of the WTN.

5. In the principal judgment, I determined that the dominance of the WTN which was evident on the majority of the audio recordings was not a constant state of affairs. On the contrary, the nature of WTN is that periods of adverse impact are likely to be intermittent. However, I accepted that adverse impact occurs commonly, persists for sustained periods, and would be particularly evident at night. 

6. Liability having been determined, remedy and quantum of damages would require to be adjudicated in module 2.

7. In the principal judgment, I found that due to the complex range of interrelated causative factors, [4] identifying the conditions under which unreasonable adverse impact arises and devising mitigation measures would be an iterative exercise. As noted by the defendant's expert, Mr. Carr, mitigation of WTN is often a process of trial and error. This is best approached on site and not in a courtroom. A court order is an unsuitably blunt instrument with which to tailor a remedy to address WTN nuisance without unnecessarily inhibiting the operation of T2.  In light of the social utility of renewable energy, I would not order the shutdown of T2, even just at sensitive periods, if a more tailored solution could ameliorate the nuisance. I therefore directed the parties to engage in mediation in an attempt to agree appropriate mitigation measures to abate the nuisance in advance of module 2.


8. The mitigation exercise subsequently ran from 15th July to 30th September 2024. The defendant trialled just one potential mitigation measure. T2, which was manufactured by Enercon, normally operates in Enercon mode 2,300 KW ("the 2300 mode"). The defendant trialled Enercon mode 1,600 KW (" the 1,600 mode") . This operation mode reduces the speed of the rotors at higher wind speeds, with the aim of lowering WTN levels which potentially reduces power output by up to 30%. The defendant collected noise monitoring data on foot of this trial ("the 2024 1,600 mode data"). It did not carry out any further monitoring of the WTN in the 2,300 mode, to provide a baseline for mitigation measures or to investigate the conditions under which adverse impact occurs. It did not implement a period of turbine shutdown to assess background noise levels.

9. The plaintiffs maintained that the 1,600 mode does not abate the nuisance. The defendant disagreed. Both remedy and quantum of damages therefore required to be determined in module 2. In respect of remedy, the defendant submitted at case-management hearings, that the plaintiffs ought to be confined to damages in lieu of an injunction ("damages in lieu"). If the court held for the defendant on this issue, then it would be necessary to assess damages for both past and future nuisance. The court was informed that, if it ordered damages in lieu, Ms. Webster intended to leave Hill House ("HH") and would then seek the costs of alternative accommodation ("the accommodation claim") as part of her claim to damages for future nuisance.  Irrespective of the merits or de-merits of the accommodation claim, its adjudication would add to the duration and costs of the hearing of module 2. [5] On the other hand, the accommodation claim would not arise at all should the court decide to grant an injunction restraining future WTN nuisance (rather than confining the plaintiffs to damages in lieu for such future WTN nuisance). [6] I therefore determined that module 2 ought to be subdivided into two parts. The first part of module 2 would determine whether the plaintiffs ought to be confined to damages in lieu for future WTN nuisance or whether future WTN nuisance should be abated by injunction (and the precise terms of any such injunction). If the plaintiff were to be confined to damages in lieu, the second part of module 2 would then assess damages for both past and future WTN nuisance. If on the other hand, future WTN was to be restrained by injunction, then the second part of module 2 would assess damages for past WTN nuisance only.  


10. Accordingly, the issues for determination in this judgment are whether the plaintiffs ought to be confined to damages in lieu or whether the nuisance should be abated by injunction and, in the latter instance, whether this court should order turbine shut down or some other form of restricted operation. The assessment of damages for WTN nuisance does not presently arise.


11. Because they maintain that the mitigation mode has not resulted in an abatement of the nuisance, the plaintiffs seek an order directing the shutdown of T2 during sensitive periods. The defendant's position is somewhat hard to discern. Its original argument, subject to its right to appeal, was that restricting T2 to the 1,600 mode during sensitive times fully abated the nuisance. Now, however, the defendant's principal argument is that the WTN does not pose a nuisance to the plaintiffs even in the 2,300 mode and that no mitigation is therefore required. 


12. The defendant has always reserved its right to appeal this court's finding on liability in module 1. There is nothing controversial about this. Such appeal should, in accordance with established principles, proceed on the evidence presented to the court in the course of module 1.


13. However, rather than confining itself to the matters falling for determination in module 2, the defendant has sought to adduce new evidence on the issue of liability, to which the plaintiffs take objection. The defendant also argues that, on the basis of this new evidence, I should revisit my finding on liability made at module 1. The plaintiff resists the re-opening of the principal judgment.



14. As same is in dispute, it is first necessary to delineate the evidence which I will admit in module 2 and to decide whether this court will re-visit its principal judgment.

The delineation of the evidence for module 2

Background chronology


15.         In preparation for module 2, the parties exchanged expert reports and statements of evidence.  A substantial part of Mr. Carr's report and statement is devoted to demonstrating that, in the 2,300 mode, total operational noise levels [7] do not cause a nuisance to the plaintiffs and that there is no requirement for noise mitigation (save where the context otherwise requires, I will refer to this as "the disputed new evidence").  The parties' reports and statements were furnished to the court several weeks before the hearing of module 2.  On considering same, I listed the matter for mention. I queried the basis upon which the defendant sought to adduce the disputed new evidence given that, subject to an argument that the plaintiffs should be confined to damages in lieu, module 2 was confined to determining what abatement measures ought to be ordered to obviate the WTN nuisance. I indicated that the court did not propose to have regard to evidence which did not pertain to these issues.


16. No application was made by the defendant for leave to adduce the disputed new evidence. Nor, prior to the hearing of module 2, was any application made by the plaintiffs to redact or exclude same. On day 1 of module 2, I requested legal submissions from the parties on the admissibility of the disputed new evidence. Unfortunately, neither party appeared ready to address this issue at that time. I therefore took up the evidence of Mr. Brazil, the director of the defendant company. In his direct evidence, Mr. Brazil referred to part of the disputed new evidence. Before commencing his cross examination, counsel for the plaintiffs applied to exclude the disputed new evidence. I directed the plaintiffs to identify the precise portions of Mr. Carr's report and statement to which they took objection and to notify same to the defendant overnight.  I directed that, in the first instance, the parties should explore whether redaction of any portion of Mr. Carr's report and statement could be agreed.


17. When the matter resumed the next morning, the parties informed me that no agreement had been reached on redaction. I therefore proceeded to hear legal submissions on the admissibility of the disputed new evidence.


18. At the conclusion of the legal submissions, I ruled that certain portions of the disputed new evidence could not, on any conceivable basis, fall within the scope and rationale of the defendant's argument for admissibility.  I therefore ordered the redaction of limited portions of Mr. Carr's report.


19.   I determined that, in light of a particular argument advanced by counsel for the defendant (which I will explain at para. 55 et seq. below), it was necessary to hear expert evidence before reaching a conclusion on the admissibility of the bulk of the disputed new evidence.  I therefore received Mr. Carr's report and statement (save for the limited portions already redacted) on a de bene esse basis and deferred my final ruling on admissibility to this judgment.  I now set out this court's ruling on admissibility.

 

Nature of the disputed new evidence


20. In order to understand the court's ruling on admissibility, it is necessary to describe the disputed new evidence in some detail. It comprises Mr. Carr's new analysis of the raw noise monitoring data presented to the court by the plaintiffs in the course of module 1. The raw data consists of external audio recorded by Ms. Sarah Large in 2017 at Nettlefield, which was at that time owned by Mr. Shorten and Ms. Carty ("the 2017 NF data").


21. The defendant has now carried out what Mr. Carr terms an "AM assessment" of the 2017 NF data. An "AM assessment" can be explained as follows: older planning guidelines such as The Wind Energy Development Guidelines 2006, issued by the Department of the Environment, Heritage and Local Government in December, 2006 ("WEDG 2006"), make no express allowance for AM. However, in 2014, as the impact of AM came to be appreciated, the Institute of Acoustics ("the IOA") developed a method for measuring AM, the Reference Method ("the IOA RM"). [8]  Although the IOA RM sets out the methodology for calculating AM values, it does not set a limit of acceptability for AM values, either for planning or for nuisance purposes.  In 2016, a Report, commissioned by the Department for Business, Energy & Industrial Strategy  ("the Phase 2 Report") recommended that AM controls at the planning and development stage were best achieved by means of a suitable penalty scheme, whereby increasing levels of AM would attract a decibel penalty ("AM penalty"), which would be added to the relevant WTN levels for the purposes of fixing decibel limits and testing compliance therewith. The Phase 2 Report suggests the following AM penalties:

·         For AM with a peak to trough level of less than 3dB: no AM penalty

·         For AM with a peak to trough level of 3dB to 10dB: a sliding scale of AM penalties ranging from 3dB to 5dB

·         For AM with a peak to trough of equal to or greater than 10dB: a 5dB AM penalty


22.         The Phase 2 penalty scheme has not been adopted in either Great Britian or Ireland. However,  the Draft Revised Wind Energy Development Guidelines, published by the Department of Housing, Local Government and Heritage in December 2019 ("draft  WEDG 2019") does utilise it. Although draft WEDG 2019 has since been withdrawn, the methodology it employs, as opposed to the detailed noise limits therein, is still instructive.


23.         The disputed new evidence is a new analysis of the 2017 NF data consisting of the following steps:

2017 NF data: calculation of noise levels by windspeed


24. Mr. Carr analyses the raw data gathered by Ms. Large and tabulates total operational noise levels by windspeed.

2017 NF data: calculation of AM value in accordance with the IOA RM


25. Mr. Carr has measured AM values per windspeed in accordance with the IOA RM ("Carr's IOA RM analysis").

2017 NF data: calculation of AM penalty in accordance with the Phase 2 Report


26. Mr. Carr has calculated the applicable AM penalty per windspeed in accordance with the Phase 2 Report [9] and presented same on a series of spiderweb graphs. [10]

2017 NF data: add AM penalty to the calculated noise level per windspeed


27. Mr. Carr has calculated and tabulated total operational noise levels plus AM penalties ("the penalised noise level") per windspeed.

2017 NF data: comparison of the penalised noise level per windspeed with WEDG 2006


28. Mr. Carr has then compared the penalised noise level per windspeed with the fixed night time limit in WEDG 2006, which he contends is 43dB. [11]

2017 NF data: Mr. Carr's conclusions


29. Mr. Carr concludes that the penalised noise levels in the 2,300 mode are lower than the WEDG 2006 noise limit and that nuisance is thereby excluded. I will refer to this entire analysis as "the Carr comparative exercise". I should say that Mr. Carr has carried out precisely the same analysis of the WTN in the 1,600 mode and has reached a similar conclusion: the penalised noise levels in the 1,600 mode are lower than the WEDG 2006 noise limit and nuisance is thereby also excluded.

Legal principles regarding the admissibility of new evidence and the re-opening of a court's prior judgment


30.         The defendant cites Greenwich Project Holdings Ltd v. Con Cronin [2021] IEHC 145 in which  Hyland J. observed that where an application is made to revisit a judgment, the court must decide if there are strong reasons for so doing. The defendant argues that strong reasons exist in this case, and that, accordingly I should admit the disputed new evidence and revisit my finding on liability. In oral argument, counsel for the defendant invoked the following principles identified by Finlay C.J. in Murphy v. Minister for Defence [1991] 2 IR 161:

"1. The evidence sought to be adduced must have been in existence at the time of the trial and must have been such that it could not have been obtained with reasonable diligence for use at the trial;

2.    The evidence must be such that if given it would probably have an important influence on the result of the case, though it need not be decisive;

3.    The evidence must be such as is presumably to be believed or, in other words, it must be apparently credible, though it need not be incontrovertible."


31. These principles were developed in the context of the admission of new evidence on appeal. However, in Re McInerney Homes Ltd [2011] IEHC 25, Clarke J. (as he then was), applied them to a case in which judgment had been delivered, but final orders had yet to be made. Clarke J. held that the test for the admission of new evidence in such circumstances should be at least as exacting as the test applying at the appeal stage. This was approved by the Supreme Court on appeal [2011] IESC 31.


32. In Inland Fisheries Ireland v. O'Baoill [2015] IESC 45, the Supreme Court applied the above principles to an application to admit new evidence in a modular trial. Clarke J. acknowledged that, in a modular trial, no formal issue of res judicata arises out of the findings of an earlier module. Nevertheless, formal findings of the court on a specific issue determined in an earlier module should only be reopened in exceptional circumstances. It would defeat the purpose of a modular trial if a party could easily and for little good reason, seek to reopen matters already determined, when the court came to consider later modules. Whilst the court has room for manoeuvre to do justice between the parties, it should not, without good and strong reason, enable any finding to be revisited in a subsequent module. In essence therefore, a modular trial remains in being until all modules are concluded and there is no formal jurisdictional barrier to allowing new evidence in to reopen a point already decided. However, this is a jurisdiction to be exercised sparingly.


33. Costello J. (as she then was) also considered when it might be appropriate to admit new materials to re-open a judgment in Hinde v. Pentire Property Finance Designated Activity Company & Kavanagh [2018] IEHC 575. [12] Costello J. observed that the test to re-open a judgment contains two elements, namely:

·         The new materials would probably have an important influence on the result of the case and be credible.

·         Such new evidence will not ordinarily be permitted to be relied on, if it could, with reasonable diligence, have been put before the trial court.


34. More recently, in Bailey v. Commissioner of An Garda Siochana [2018] IECA 63, the Court of Appeal confirmed that a court of first instance has jurisdiction to revisit an issue decided in a written judgment. The test is whether the court is satisfied that there are " exceptional circumstances" or "strong reasons", which warrant it doing so.

Application of legal principles in relation to the admissibility of new evidence


35. The parties' oral legal submissions focussed primarily on Murphy criterion 1, whether the evidence sought to be adduced could with reasonable diligence have been obtained for use at the trial.


36. During the course of module 1, both Ms. Large and Mr. Stigwood gave extensive direct evidence presenting and commenting upon, inter alia, the 2017 NF data.  A substantial number of graphs derived from this data were placed before the court in reports by Ms. Large, running to 150 pages.  Ms. Large also gave oral evidence in relation to the features of the WTN appearing on these graphs. In addition, audio recordings taken from the 2017 NF data were played to the court by Mr. Stigwood (along with audio recordings of other data), who also provided his professional opinion in relation to the features of the WTN. Both Ms. Large and Mr. Stigwood were subject to lengthy cross examination. 


37. Having considered the expert reports, the audio recordings, the evidence emerging from the direct and cross examination of Ms. Large, Mr. Stigwood, Mr. Carr and Mr. O'Reilly, together with all of the factual evidence in the case, the court accepted Ms. Large's opinion (and much of Mr. Stigwood's opinion) as to the intrusive features of the WTN and delivered judgment on that basis. The defendant may not belatedly challenge the evidence and opinion of Ms. Large (and Mr. Stigwood) by ex post facto analysis of the data she presented.


38. The 2017 NF data was furnished to the defendant in advance of the trial of module 1. It had every opportunity to comment upon this data, to advance a contrary analysis thereof and to challenge the opinions of the plaintiffs' experts in relation thereto. Further, although the defendant had ample opportunity to conduct the IOA RM analysis of the 2017 NF data now sought to be adduced, it carried out no analysis of its own of this data for the purposes of module 1. Indeed, I was extremely surprised that it did not do so. The defendant also had every opportunity to subject the 2017 NF data to the Carr comparative exercise now sought to be adduced. Furthermore, the defendant elected not to perform an IOA RM analysis on any of the data gathered by its own expert in Module 1, Mr. O'Reilly.


39. On this basis it could not possibly be said that the disputed new evidence "could not have been obtained with reasonable diligence for use at the trial?"

Does the new technical specification published by the International Electrotechnical Commission provide a justification for the introduction of the disputed new evidence?

Justification advanced in Mr. Carr's report


40. It is common case that the defendant could have put an IOA RM assessment of either the 2017 NF data or its own data before the court at module 1. Permitting the introduction of new evidence at module 2 simply because the relevant matters were not advanced at module 1 would be a recipe for procedural chaos. In apparent reply to this objection, Mr. Carr's report cites para. 375 of the principal judgment as follows:

"I should say that this court would place very considerable weight upon up-to-date, scientifically robust planning guidelines on wind energy developments which advised on the particular decibel level at which WTN, when combined with AM of a particular nature, is considered an acceptable interference with amenity. If responsive to the particular aspect of the noise complained of, such guidance would be highly persuasive in a nuisance action. A plaintiff who sought to argue that such guidance did not represent a reliable - if not a wholly reliable - indicator of what is objectively reasonable would, in my view, bear a heavy onus. However, no such guidance currently exists; planning guidance in this jurisdiction (and elsewhere) can fairly be described as flux and cannot identify the line of acceptability."


41. Mr. Carr's report states since the date of the principal judgment, an important new IEC technical specification has been published (IECTS 61400-11-2:2024, acoustic noise measurement techniques, measurement of wind turbine sound characteristics in receptor position) ("the IEC"). The defendant argues that the IEC was not in existence and could not have been obtained with reasonable diligence for the use at the trial. Essentially, therefore, the defendant argues that the IEC is new evidence emerging since the trial and, further, that it meets the lacuna identified in para. 375 of the principal judgment. I will take these points in reverse order.

 

The IEC does not meet the lacuna identified in para. 375


42. The IEC does not constitute "scientifically robust planning guidelines on wind energy developments which [advise] on the particular decibel level at which WTN, when combined with AM of a particular nature, is considered an acceptable interference with amenity" in the sense contemplated by para. 375 of the principal judgment.  


43. The IEC does not dictate or even recommend any regulatory metrics. Rather, it provides guidance on how best to isolate WTN for comparison with local regulation. It also provides guidance for the quantification of the impact of the sound characteristics of the WTN, such as AM values, again for comparison with local regulation.   The IEC does not delineate what level of noise or what AM values are acceptable in terms of interference with amenity. The proposition that the IEC is responsive to the lacunae identified at para. 375 is entirely erroneous.

 

The IEC is not the disputed new evidence


44. It is well established that where the new evidence tendered is in respect of matters occurring after the judgment from which an appeal is brought, no special leave is required. If the evidence was not in fact "in existence at the time of the trial", then the failure to adduce it is not attributable to any omission on the part of the party seeking to introduce it. The power of the court to receive such evidence is discretionary. The interests of justice may require its admission, particularly if it would have an important influence on the result of the case.


45.  In the present case, however, this does not assist the defendant. Although the IEC post-dates the principal judgment, the disputed new evidence sought to be adduced is not the IEC per se. The disputed new evidence is Mr. Carr's IOA RM analysis of the 2017 NF data and his ensuing comparative exercise. The IEC is merely the vehicle through which the defendant seeks to introduce this evidence.


46. The fact that the IEC had not been published prior to the hearing of module 1 cannot reasonably justify or explain the defendant's failure to carry out, and to tender to the court, an IOA RM analysis and the ensuing comparative exercise at that time. The IEC cannot justify the defendant's 13th hour attempt, after judgment has been handed down against it, to attempt to plug this very obvious lacuna in its proofs.


47. In order to link the disputed new evidence to the IEC, Mr. Carr explains that the IEC "implements" the IOA RM "for quantifying AM". He observes that the IEC identifies the IOA RM as the chosen AM assessment method. The argument appears to be that the IEC represents best practice in the measurement and assessment of WTN and that its endorsement of the IOA RM is a new development legitimising the late admission of the disputed new evidence.


48. However, endorsement of the IOA RM is nothing new. As observed in the principal judgment, draft WEDG 2019 also identified the IOA RM as the most robust methodology for measuring AM, as did the ETSU Review of 2023. In the principal judgment, I fully accepted that the IOA RM was a robust methodology. [13] The further endorsement of the IOA RM by the IEC neither explains why the IOA RM analysis of the 2017 NF data was not presented at module 1, nor justifies its admission now.


49. Mr. Carr emphasises that the IEC is specific to WTN. However, this is irrelevant as the IOA RM was also WTN specific. He also points out that the IEC defines AM as including both swish and thump AM. This was also the case in respect of IOA RM. There is little new here to justify the admission of the disputed new evidence.


50. Despite suggestions to the contrary in legal argument and in aspects of Mr. Carr's oral evidence, the IEC is not an international standard. It is a technical specification. Para. 3.1.5 of the 'ISO/IEC Directives, Part 2', Principles and rules for the structure and drafting of ISO and IEC documents (9th edn, 2021), defines a technical specification as being one in respect of which there is a future possibility of agreement on an international standard but for which at present:

·                     the required support for approval as an international standard cannot be obtained,

·                     there is doubt on whether consensus can be achieved,

·                     the subject matter is still under technical development, or

·                     there is another reason precluding immediate publication as an international standard.


51. Mr. Stigwood also gave evidence that the IEC has not yet been adopted by the relevant Irish or European authorities. No evidence to the contrary was presented by the defendant.


52. Furthermore, the relevant sections of the IEC dealing with the assessment of AM are said to be "informative", rather than "normative". Whilst a normative element of a document provides rules or guidelines, an informative element is merely intended to assist the understanding or the use of the document or to provide contextual information about its content, background or relationship with other documents. This also undermines the weight to be attached to this aspect of the IEC.


53. The IEC is not therefore a transformative piece of evidence sweeping away the defendant's omission to present the disputed new evidence. The position is all the more stark in light of the defendant's trenchant criticism at module 1 of Mr. Stigwood's failure to carry out a formal IOA RM assessment. Despite contending that the IOA RM was a robust methodology, and indeed that it was the exclusive methodology for assessing WTN AM, [14] the defendant did not carry out such an analysis. As it would stretch credulity to suggest that it had not occurred to the defendant to do so, its failure to carry out (or if carried out, to present) an IOA RM analysis at module 1, can only be seen as a deliberate decision.


54. In short, the report of Mr. Carr and its accompanying statement reveal no argument that the IOA analysis of the 2017 NF data (and the entire Carr comparative exercise) could not, with reasonable diligence have been adduced at module 1.

 

Alternative justification advanced by the defendant in oral legal submissions: substantial differences between the IOA RM analysis and the IEC AM analysis


55. In legal argument on day 2, the defendant introduced the concept of separate and defined IEC analysis of AM ("IEC AM analysis"). Counsel argued forcefully that there are material and substantial differences between the IOA RM analysis and the IEC AM analysis. When compared with the IOA RM analysis, the IEC AM analysis was "a different standard that reaches a different result", such that Mr. Carr's IEC AM analysis is in fact new evidence that could not with reasonable diligence have been adduced at module 1. [15]


56. This was a surprising submission because Mr. Carr's report and statement did not refer to any significant or material differences between the two methodologies and their results.  On the contrary, Mr. Carr's written evidence depicts the IEC as endorsing the IOA RM.


57. The nature and relevance of the apparent distinction between the IOA RM and IEC AM methodologies (and their results) appeared to me to be highly technical. In legal argument, counsel frankly conceded that he did not fully understand it. As such, I was persuaded that I could not rule on admissibility on the basis of legal argument alone. I therefore decided to receive the disputed evidence de benne esse so I could hear expert evidence before ruling on the admissibility of the disputed new evidence.


58. When Mr. Carr came to give evidence it became apparent that any difference between the two methodologies could not possibly justify the admission of the disputed new evidence. Mr. Carr explained that for technical reasons which it is not necessary to detail here, the IOA RM has the capacity to miss low frequency AM, and that this issue had been remedied in the IEC AM assessment methodology. [16] [17]


59. This potential under-estimation of low frequency AM neither explains nor justifies the defendant's failure to present an IOA RM analysis at module 1. Indeed, such rationale is entirely contrary to the defendant's committed position throughout module 1. This was that the IOA RM analysis was not just a reliable methodology to assess AM, including thump AM, but that it was the only acceptable methodology. The defendant offered no qualification to its support of the IOA RM and never allowed for the possibility that it could miss thump AM. Nor, as I recall, did the plaintiffs' experts dwell on this issue; and I did not refer to it at all in reaching my findings at module 1.


60.  In addition, far from producing materially different results, Mr. Carr's evidence at module 2 was that one could expect the results of the two assessments to be broadly similar, albeit that the IEC AM assessment was "more conservative" than the IOA RM, because it took full account of thump AM.


61. Therefore, whilst I accept that there are some differences between the IOA RM and the IEC AM analysis, these are not of particular relevance to the issues that were before the court in module 1 (or indeed those arising in the present module) and in no way explain the defendant's failure to perform and present an IOA RM analysis at the appropriate time.

Conclusion on criterion 1 of Murphy v. Minister for Defence


62. With any diligence, the disputed new evidence could have been adduced at module 1. I am driven to conclude that the defendant has seized upon the IEC as a contrivance to, as it sees it, mend its hand. The IEC does not set a new standard for nuisance. It is a measurement methodology which is still in development. It has not yet been adopted in Ireland. The IOA RM analysis and the IEC AM analysis are not substantially different. Any distinctions between the two are of no real relevance to the issues arising in this case.  The IEC cannot possibly justify the defendant in now presenting an analysis of data that was furnished to it in 2022.


63. As O'Donnell J. (as he then was) observed in Emerald Meats v. Minister for Agriculture [2012] IESC 48, a trial is not a laboratory experiment where one element can be substituted, all other elements maintained and a different outcome obtained. There are very few cases in which the losing side does not regret that different witnesses were not called, different evidence given or different points made in cross examination or submission. There are few cases which in hindsight could not be rerun with different witnesses, evidence, arguments or advocates. But to consider that such a course is in the interests of justice is to engage in the delusion that endless litigation is a desirable, rather than a tormented state. The court has made its decision on the evidence advanced over 51 days. The defendant may reasonably dispute the merits of this court's conclusion; but it cannot doubt that it is the conclusion. In short, the Murphy criteria do not permit the admission of the disputed new evidence.

Is the disputed new evidence admissible qua baseline assessment?


64. The defendant also submits that the purpose of collecting the disputed new evidence was not to challenge this court's findings at module 1, but to establish a baseline to guide potential mitigation strategies.


65. I fully accept that a mitigation strategy is best devised on foot of complete and reliable baseline data. However, if the defendant had wished to carry out a baseline assessment then it should have gathered data directed to that purpose, rather than re-interring the plaintiffs' 2017 NF data.


66. I am not satisfied, as a matter of fact, that the IOA RM analysis (and the ensuing Carr comparative exercise) was a bone fide baseline assessment. The defendant's evidence on this issue is inconsistent. In closing argument, counsel for the plaintiffs directed the court to evidence suggesting that the defendant only analysed the 2017 NF data after the 1,600 mode mitigation trial had been completed. The defendant did not reply at all to this aspect of the plaintiffs' closing submissions.


67. If the disputed new evidence was, as the defendant contends, gathered to guide the mitigation trial, then why did it not inform that mitigation? Surely a mitigation programme guided by the disputed new evidence would have focussed on reducing noise levels at windspeeds associated with the highest AM values. Yet the defendant designed a mitigation programme which did precisely the opposite; the 1,600 mode produces no reduction whatsoever in WTN at the windspeeds when AM values are highest.


68. More importantly, the disputed new evidence does not comprise a useful or complete baseline assessment. As it presents only total operational noise, it does not actually inform one on WTN levels. The disputed new evidence does not include an assessment of background noise levels in what is clearly a very quiet and sheltered rural area. It does not assist on the question of whether this is a "low noise environment" within the meaning of WEDG 2006. [18] No data or analysis whatsoever is presented on the important issues of emergence of the WTN over background noise or low frequency noise/thump AM (even though the IEC treats of both). As will become apparent, the lack of evidence on background wind noise levels and its efficacy in masking WTN at different windspeeds is a critical omission. The disputed new evidence does not even present AM values in the manner required by either the IOA RM or the IEC. Instead of presenting AM values, it rather presents AM penalties only.


69. A "baseline" is a starting point to be used for comparison. It will only be of value if it comprehensively presents the relevant data points. Here, the defendant has cherry-picked from the IEC and has presented only one suite of data (AM penalties and total operational noise levels), whilst omitting other important data, which one would expect in any valid baseline study.


70. Furthermore, whilst the disputed new evidence does present AM penalties in the 2,300 mode at a range of wind directions and windspeeds, the same information can be gleaned from the 2024 1,600 mode data. This is because it is common case that the turbine's operational mode does not alter AM values. Nor does the operational mode impact upon spectral frequency, thump AM, erraticism or impulsivity. [19] Therefore, any findings of fact that I may make in relation to these WTN characteristics in relation to the 1,600 mode apply equally to the 2,300 mode. Analysis of the 2017 NF data does not assist one's understanding of these features of the WTN.


71. I conclude that the evidence already put before the court at module 1, the 2024 1,600 mode data and the totality of the other evidence from module 2, are sufficient for the court to determine the issues at hand. I therefore decline to admit the disputed new evidence and will admit Mr. Carr's report and statement and Mr. Brazil's statement in redacted form only. Essentially whilst I admit the data pertaining to the 2024 1,600 mode, I exclude the 2017 NF data. 


72. However, lest I am wrong in any of my above analysis, I will now explain for completeness why the disputed new evidence (if admitted) would not have an important influence on the result of the case. In other words, even if admitted the disputed new evidence would not substantially impact or alter my findings on liability at module 1.

The disputed new evidence would not substantially impact or alter my finding on liability

The IOA RM analysis of the 2017 NF data supports, rather than undermines this court's finding on AM values in the principal judgment


73. The IOA RM analysis of the 2017 NF data, which I have decided to exclude supports, rather than undermines, this court's finding of regular and sustained periods of typical AM values at a level widely acknowledged to be associated with high levels of annoyance. This finding in the principal judgment had three components. 


74. As a first component, I accepted Ms. Large's evidence that on foot of her 2017 monitoring, AM values significantly in excess of 5 dB are a substantial feature of the WTN. I found that the time-domain graphs revealed a common thread of AM values in excess of 5 or 6 dB and that they also showed that AM values of 10 dB are frequently present, both externally and internally. Indeed, this was not disputed by the defendant. Although the disputed new evidence does not comply with the IEC reporting requirements for AM assessment, it is nonetheless common case that at night in the downwind direction  average AM values at windspeeds between 4m/s and 8m/s are between 6.5 and 10dB. Clearly, there will be periods when AM values are lower than this. However, there will also be periods when AM values are higher. Indeed, the prevalence of AM average penalty points of 4-5 dB on the spiderweb graphs, demonstrates that AM values of 10 dB occur regularly .


75. As a second component, I accepted Ms. Large's evidence that AM values of 5 dB and above, if audible at a sufficient level are capable of amounting to an unreasonable impact. This finding is in no way impacted by the disputed new evidence.


76. As a third component, this court's findings of fact that the WTN AM was "audible at a sufficient level" was based, inter alia, on its own experience of the audio recordings. I found that on the majority of the audio recordings, both internal and external, the WTN is the only noise that one can consistently identify. Its nature is such that it constantly draws one's attention and it was not masked by other ambient noise. This finding of fact was also based on the oral evidence of the plaintiffs themselves in relation to their experience of the WTN and on the direct evidence of their experts, none of which was undermined in cross examination. I fail to see how the disputed new evidence should incline this court to revisit any of this. In short, the evidence sought to be admitted would not have an important influence on the court's findings as to the nature and impact of the AM values.

 

The disputed new evidence does not undermine this court's finding on low frequency noise and thump AM


77. The principal judgment finds that there is a significant audible lower frequency component to the WTN. This is both heard and felt as a vibration or sense of pressure. This also manifests as thump AM which I found was the "most intrusive" element of the WTN. This finding was based on the audio recordings, the evidence of the plaintiffs and the expert evidence of Ms. Large in particular (which in this respect was essentially uncontradicted by Mr. Carr's testimony).


78. The disputed new evidence does not even address, still less undermine this finding. The defendant carried out no analysis of low frequency sound at module 1. This remains the position.


79. It is common case, that neither the IOA RM nor the IEC AM analysis differentiate between swish and thump AM. Although thump AM is widely acknowledged to be more annoying and intrusive than swish AM, these methodologies assign the same value to both forms of AM. This may be a perfectly good starting point from a regulatory perspective but it does not provide a complete answer to a nuisance claim in which thump AM is the most intrusive element.

 

The disputed new evidence does not undermine this court's finding on dominance

80. Para. 510 of the principal judgment, concludes that the dominance of the WTN is most likely due to a combination of high AM values, low frequency AM, the emergence of the WTN over low background noise levels ("emergence") and to its other intrusive features such as erraticism, impulsivity, unpredictability, etc. At module 1, the defendant declined to carry out or present any reliable analysis of background noise levels, emergence or of the other intrusive features just discussed. That omission persists.

 

The defendant's reliance on a combination of WEDG 2006, the IEC and the Phase 2 penalty scheme is misplaced


81. The defendant's "Eureka moment" is that the Carr comparative exercise shows that penalised noise levels in the 2,300 mode do not exceed "the 43dB limit level in the WEDG 2006". This is said to foreclose WTN nuisance in the 2,300 mode (and a fortiori in the 1,600 mode).


82. To develop this a little further, the defendant points to several passages in the principal judgment. These are to the effect that WEDG 2006 is not the determinant of nuisance because it is not a yardstick, objective or otherwise, against which to assess what particular AM values or what particular degree of thump AM is objectively reasonable. The defendant argues that the Carr comparative exercise now accounts for these deficits in WEDG 2006, because it penalises AM values. The Carr comparative exercise is said to supply the missing yardstick.


83. There are, to put it mildly, difficulties with this approach.

 

Argument inconsistent with the defendant's position at module 1

84. First the argument that such comparative exercise is the determinant of nuisance, is entirely inconsistent with the case presented by the defendant at module 1, which was that the 2004 planning permission was a wholly reliable indicator of what was objectively reasonable at this locality.

 

Lacuna: WEDG 2006 does not address thump AM

85. Second, even within its own four corners, the Carr comparative exercise contains a serious lacuna. It addresses only one of the two omissions just discussed. It addresses only the failure of WEDG 2006 to account for AM values. It does not address the second omission, the failure to take account of the added intrusion of thump AM.

 

WEDG 2006 was not drafted with nuisance in mind


86. Third, the principal judgment does not state that were it not for these two specific omissions, the WEDG 2006 noise limits (with which, for the sake of argument, the principal judgment accepted the WTN complied), would be the determinant of nuisance.  WEDG 2006 was not drafted with nuisance in mind.

 

WEDG 2006 was not drafted with AM in mind

87. Fourth, WEDG 2006 was also not drafted with AM in mind. The IOA RM and Phase 2 Reports, postdate WEDG 2006 by a decade. The IEC, upon which the defendant now places reliance, postdates WEDG 2006 by almost two decades. There is no logic in bolting penalties for AM developed 10 to 20 years later onto the noise limits set out in WEDG 2006. Indeed, this is clear from the IEC itself, which states that any adjustments to noise limits "are typically defined in local regulation" (emphasis added). WEDG 2006 does not define, or even contemplate, adjustments to noise limits by reference to AM values. WEDG 2006 is an entirely different methodology. WEDG 2006 is a round hole into which the defendant seeks to force a square peg, the Phase 2 penalties scheme.

 

WEDG 2006 is under review and takes no account of low frequency WTN


88. Fifth, if the Phase 2 penalty scheme is to be bolted on to any methodology as the determinant of nuisance, then why logically should that methodology be WEDG 2006? The defendant's answer to this question appears to be: WEDG 2006 is still relied upon in the planning and development of windfarms. I accept that s. 28 of the Planning and Development Act 2000 continues to require planning authorities and An Bord Pleanála to have regard to ministerial guidelines such as WEDG 2006. However, that does not imbue WEDG 2006 with talismanic significance for the purposes of a nuisance assessment.


89. WEDG 2006 is currently under review. There is evidently a range of potential methodologies that the Government might adopt to replace it for planning and development purposes. There is no reason to assume that new Guidelines will ape the "flat" night time noise limit of 43 dB (whether including AM penalties or not). Still less can one assume that new Guidelines will apply this noise limit irrespective of the frequency of the WTN or of background noise levels.  Indeed, I would have thought that this is unlikely.


90. There is therefore no reason why this court should accept that a "flat" night time noise limit of 43 dB (whether including AM penalties or not) is the determinant of nuisance. The principal judgment observes that the current direction of travel in wind energy planning guidance ("the modern planning approach") is towards setting decibel limits, combined with a penalty for character such as AM. I accept that the Carr comparative exercise, which combines WTN levels and AM penalties, reflects this aspect of the modern planning approach. However, the principal judgment goes on to observe that the modern planning approach incorporates limits on low frequency noise.  For example, unlike WEDG 2006, draft WEDG 2019 limits low frequency noise. This important criterion is absent from the Carr comparative exercise.

 

WEDG 2006 takes no account of night time background noise levels  


91. Sixth, the modern planning approach in publications such as draft WEDG 2019, is to take background noise levels into account in setting WTN limits. Draft WEDG 2019, notes that the principle of a 5 dB emergence has been regarded as good practice for many years.


92. WEDG 2006 appears to consider that WTN should assessed by reference to background noise levels. It provides:

 "Noise impact should be assessed by reference to the nature and character of noise sensitive locations.... Noise limits...should reflect the variation in both turbine source noise and background noise with wind speed."


93. Ultimately, however WEDG 2006 appears to allow the planning authority to select a higher WTN day time noise limit of up to 45dB if considered appropriate [20] (save in "low noise environments"). It also imposes a "flat" 43dB noise limit at night, regardless of background noise levels.


94. By contrast, draft WEDG 2019 generally limited WTN to 5 dB above background noise levels at night time as well as during the day time (irrespective of whether the windfarm is in a low noise environment). In a typical quiet rural site this would tend to limit night time WTN to levels below 43 dB for low to moderate windspeeds. However, this modern planning approach is not reflected in the defendant's comparative exercise.


95. In short, the Carr comparative exercise translates AM values into an estimated decibel level for regulatory purposes but ignores all other important characteristics of the WTN such as low frequency noise, emergence over background noise and the time of occurrence of the AM. I am not convinced that such a methodology remotely accords with the modern planning approach or with best practice in the assessment of WTN nuisance.

 

S. 28 is not the yardstick of nuisance


96. Seventh, the defendant relies on Nagle v. An Bord Pleanála [2024] IEHC 603 ("Nagle") as endorsing WEDG 2006  for all purposes, including nuisance assessment. I cannot see how Nagle greatly assists the defendant. It is true that Humphreys J. held that WEDG 2006 remains the relevant ministerial  guideline for the purposes of s. 28. However, he also stated in the course of his judgment [21] at paras. 99-101, that a planning permission granted in accordance with WEDG 2006 would not be immune to a nuisance action by virtue of that fact.


97. I agree with Humphreys J., Planning guidelines, such as WEDG 2006 (and individual planning permissions) predict that, as regulated, WTN will not be an unwarranted intrusion on amenity. However, that prediction may transpire to be incorrect in a given location. This may be because the WTN displays unanticipated characteristics such as substantial low frequency noise or thump AM. It may be because low background noise at a sheltered location such as this has not been fully considered in the noise limits set. The WTN nuisance in this case is attributable to a combination of factors, only some of which have been assessed by the comparative exercise now undertaken by the defendant. Although I repeat that a plaintiff who asserts nuisance will bear a heavy burden if the WTN is in accordance with up to date and robust planning guidelines, which are responsive to the relevant WTN characteristics complained of, none presently exist, and the Carr comparative exercise is a world away from meeting that lacuna.

 

WEDG 2006 does not address most of the Defra criteria


98. Eighth, the defendant argues that because neither this court nor the plaintiffs have identified a specific WTN decibel limit (whether combined with AM penalties or otherwise) as marking the boundary of nuisance, it had "no option" but to devise a comparative  exercise which applies the "flat" night time limit of  43 dB set out in WEDG 2006.


99. As stated in the principal judgment a robust assessment of a WTN nuisance complaint cannot be conducted without reference to factors such as those discussed in the Defra methodology. [22]  In all its evidence in the course of module 1, the defendant addressed only three of the ten criteria derived from Defra ("the Defra criteria") [23]: the level of WTN, the time of day or night when the WTN occurs and, to a limited extent, the sensitivity of the complainant.  The disputed new evidence partially addresses one of the ten Defra criteria, the "type of noise", by presenting average AM penalties.  However, this evidence does not address other important aspects of the noise "type" such as variability, regularity and predictability of the noise. Further, the defendant has not considered at all the following seven important Defra criteria: whether any aggravating characteristics are present in the WTN (the spectral content of the WTN and whether thump AM is present); the characteristics of the neighbourhood where the WTN occurs; the exceedance of WTN over background noise;  the impact of the WTN on basic needs such as sleep;  how easily the WTN can be avoided; what measures could reduce or modify the WTN; and finally the duration and how often the WTN occurs.

 

The Phase 2 penalty scheme is under review

100. Ninth, Mr. Stigwood's uncontradicted evidence at module 2 is that the Phase 2  penalty scheme, which is an essential component of the Carr comparative analysis, is currently under review. In particular, consideration is being given to injecting an element to reflect modulation frequency -in the sense of the rapidity-of the AM. This could be relevant at higher speeds of rotation when AM values are lower but when AM is likely to occur with greater frequency. Mr. Carr himself drew the court's attention to clause 4.5.30 of the Phase 2 Report which includes the statement that "This method is by necessity an interim recommendation based on the available evidence to date..." Insofar, therefore, as the defendant relies upon the Phase 2 penalty scheme, it is under review, which lessens its evidential weight.

 

The IEC does not apply the Phase 2 penalty scheme

101. Tenth, the IEC itself does not, as the defendant suggests, propose that the Phase 2 penalty scheme is applied to the local regulatory limit (in this instance, WEDG 2006). The Phase 2 penalty scheme is only an example of a potential local penalty scheme. Therefore, the importance attached by the defendant to the Phase 2 penalty scheme is not, on greater scrutiny, borne out.

Plaintiffs' further argument: the Carr comparative exercise misapplies the Phase 2 penalty scheme


102. I will finally deal with a "fall back" argument advanced by the plaintiffs' acoustic expert Mr. Stigwood.  He argues that the defendant has misapplied the Phase 2 penalty scheme. This would mean that, even if I had admitted the disputed new evidence, it does not in fact show that the penalised WTN levels are lower than the WEDG 2006 noise limit.


103. To explain, Mr. Carr's comparative exercise purports to calculate penalties under the Phase 2 penalty scheme and then compare the penalised noise to the 43 dB "flat" night time limit under WEDG 2006. Mr. Stigwood observes that the Phase 2 penalty scheme fundamentally differs to WEDG 2006 in its approach to night time noise limits. This is particularly relevant in low noise environments. In low noise environments, WEDG 2006 limits day time noise to 35-40 dB. However, this lower limit is not translated across to night time limits, which are set at a "flat" 43 dB, irrespective of background noise levels. In a low noise environment, therefore the WEDG 2006 night time limit is higher than the WEDG day time limit.


104. By contrast the Phase 2 Report recognises that noise limits which are generally higher at night time than during the day, "raise the question about whether...noise limits... which are generally higher at night,  accord with current Government policies to avoid, significant adverse noise impacts, and mitigate or minimise adverse impacts." . Therefore, if day time noise limits are lower than night time limits, the Phase 2 penalty scheme effectively applies the lower day time noise limit at night by the application of additional penalties.


105. Mr. Stigwood's opinion has always been that, absent the WTN, Ballyduff is a low noise environment and that the WEDG 2006 day time noise limit is 35-40 dB. As the WEDG 2006 night time noise limit of 43 dB is higher than this, the Phase 2 penalty scheme would apply the lower of these two limits at night. On this methodology, the WTN would exceed the relevant night time noise limit.


106. The defendant does not dispute that, correctly interpreted, the Phase 2 penalty report imposes an additional penalty "if, and only if, the numerical limit for night-time is set higher than that for daytime". However, it argues that this does not result in any change to the night-time noise limit in this case. This is because the defendant contends that Ballyduff is not a low noise environment. As such the night-time limit of 43 dB is lower, not higher, than the daytime limit of 45 dB and no additional penalties apply.


107. The defendant asserts that the court concluded that Ballyduff was not a low noise environment in the principal judgment. This is incorrect. Background noise levels were a live issue in module 1, which I considered at paras. 512-528 in particular. At para. 512, I expressly noted that the absence of background noise data meant that I could not assess whether this is a low noise environment within the meaning of WEDG 2006. Therefore, as the plaintiffs contended that nuisance arose inter alia by virtue of the fact that Ballyduff was a low noise environment, and thus bore the burden of proof on that issue, I held that I could not be so satisfied on the balance of probabilities.


108. For the purposes of module 1, I therefore assumed for the sake of argument that Ballyduff was not a low noise environment. [24] I accepted arguendo that the WEDG 2006 day time limit was up to 45 dB and that the night time limit was 43dB. On that assumption, I was satisfied that the noise limits in the planning permission and the WTN itself, were in accordance with WEDG 2006. The key point however, was that compliance with the WEDG 2006 limits did not delineate the parameters of WTN nuisance in this particular case.  Irrespective therefore of whether or not Ballyduff was a low noise environment, compliance with WEDG 2006 was not determinative.


109. In summary, whether or not Ballyduff was a low noise environment was a live issue at module 1 which I did not have to decide, but which I assumed arguendo would fall in the defendant's favour. In doing so, however, I emphasised that there was no compelling evidence which would permit me to make a finding one way or the other on the issue. This remains the case.


110. At module 1, I determined that the onus of demonstrating nuisance remained at all times on the plaintiff. However, the onus of proof in substantiating its positive defence, which at that time was that the WTN complied with its planning permission, was on the defendant. We are now at a different stage of the litigation at which the defendant must surely substantiate its positive defence, which is now that on the application of the Phase 2 penalty scheme, the WTN complies with the relevant WEDG 2006 night time limit. I am satisfied the Phase 2 penalty scheme, properly interpreted, applies higher night time penalties to low noise environments. A strong argument can therefore be made that the onus of proof on this issue is now reversed and that the defendant bears the burden of proving that Ballyduff is not a low noise environment. Indeed, this would be entirely logical as only the defendant can reliably assess background noise levels which requires turbine shut down.  As the defendant has not even attempted to investigate background noise, it is hard to see how this burden could have been discharged. This would tend to suggest that the defendant has not discharged the burden placed upon it of demonstrating compliance with the Phase 2 Report/WEDG 2006 night time noise limits, as properly interpreted.


111. Having said that, I accept that the defendant's argument that low background noise was not a live issue in module 2. It was not addressed in module 2 in either parties' expert reports. The argument arises from a single observation in Mr. Stigwood's oral evidence, which I accept the defendant did not anticipate. Although I afforded the defendant an opportunity to recall Mr. Carr to deal with this issue, I accept that by that stage, it was far too late for either side to present background noise data to the court. The low background noise issue remains incompletely explored in evidence and undetermined by the court.  In these unusual circumstances, irrespective of the onus of proof, I am persuaded that it would be unfair to the defendant to hold against it on this specific point.


112.  I will therefore decline to place any reliance on Mr. Stigwood's low noise environment argument. It is, in any event, entirely unnecessary to do so. Even if one fully ignores this argument, the analysis outlined at paras. 73 to 101 above admits of only one conclusion: even if I had admitted the disputed new evidence, this would not disturb this court's finding on liability in module 1.  

Conclusion in relation to the disputed new evidence and in relation to the application to re-visit the principal judgment.


113. The defendant's written legal submissions cite the Supreme Court decision in Re McInerney Homes Ltd. in which O'Donnell J. (as he then was) expressed the view that the jurisdiction to reopen a judgment arises where a trial judge has proceeded on the basis of a particular assumption of fact which has transpired to be incorrect. In such circumstances, it could be said that the hearing, and indeed the judgment, had proceeded almost on the basis of a common mistake and that justice requires that the matter should be reconsidered. The defendant submits that there is "strong reason to re-visit the judgment" because new evidence has come to light (in the form of the IEC AM analysis of the 2017 NF data) which establishes that T2 is operating below the threshold set out in WEDG 2006.


114. However, this demonstrates no incorrect assumption of fact or common mistake in the hearing of module 1 or in the principal judgment. In the principal judgment, I assumed arguendo that the WTN noise levels did comply with the WEDG 2006 noise limits, but nonetheless found as a fact that WTN nuisance was proven on the evidence.


115. At para. 31 of their submissions, the plaintiffs state:

"What the Defendant says provides the full answer to the Plaintiffs' complaints and the test of acceptability for nuisance in Ireland is an unadopted measurement methodology linked to a proposed 2016 UK penalty scheme (itself apparently under revision) judged  against an averaged overall decibel limit in a 2006 planning guidance."


116. I cannot disagree with that characterisation. In G v. A Judge of the District Court [2023] IEHC 386 [25]  Simons J.  noted that a judge asked to review their own judgment should have regard to the fact that, on most occasions, the appropriate avenue of redress for a person aggrieved by a judgment is to exercise their right of appeal. The parties to litigation are entitled to assume that, absent an appeal, a written judgment which has been approved by the judge and has been published, is conclusive. In the present case, the defendant has provided no credible basis for the court to exercise its rare and exceptional jurisdiction to revisit its prior judgment. Regrettably, the defendant's approach has served only to add an additional layer of delay, costs and judicial decision making to already protracted proceedings.


117. I will now turn to the proper business of module 2: the assessment of the mitigation measures trialled by the defendant and the appropriate remedy.


118. I will first set out the evidence of the parties. Although the defendant's witnesses gave evidence before the plaintiffs' witnesses, this judgment will be better understood if I reverse this order.

Plaintiffs' evidence

Evidence of Ms. Webster


119. Ms. Webster continues to live alone at HH since Mr. Rollo, co-owner of the house and her former partner, left in March 2021. On foot of the principal judgment, the plaintiffs' solicitors wrote to the defendant on 15th March 2024, proposing arrangements for mediation and asking whether, pending mediation, the defendant would mitigate the noise nuisance in response to the court's findings. The defendant did not agree to any mitigatory measures pending mediation.


120. A mediation agreement was signed on 27th June 2024, [26] which provided that the defendant would implement "an iterative process of trial and error to achieve a restricted operation of T2 so that its operation does not give rise to excessive AM and WTN". The defendant would trial different modes during the mitigation period of July to September 2024. The precise design of the trial was a matter for the defendant and not the plaintiff. The plaintiffs agreed that the defendant could place noise monitoring equipment "on their land" at HH and that Ms. Webster would keep a noise diary to record the impact of the noise. It was also noted that the plaintiffs may want to place noise monitoring equipment externally and/or internally at HH and that any raw data from the plaintiffs' noise monitoring equipment would be exchanged simultaneously with the defendant's raw data.


121. The defendant's acoustic expert, Mr. Carr, placed noise monitoring equipment in the front and rear gardens of HH. In addition, Mr. Daniel Baker, Acoustic Consultant, was engaged to undertake outdoor and indoor monitoring on behalf of the plaintiff. External monitoring was carried out in the rear garden and internal monitoring was carried out in the same ground floor back bedroom as previously.


122. Ms. Webster's evidence was that the noise from the turbines was unchanged over the two month mitigation trial period. It remained most intrusive in the evenings and at night time. There was no noticeable change in the AM or in the WTN levels. Ms. Webster continues to find it difficult to enjoy her time at HH and her sleep remains disturbed. Ms. Webster's evidence was that seven and half years after her first complaint to Mr. Brazil, she continues to suffer intrusive, dominant and unreasonable WTN, which has all of the features previously found to exist by the court: "The noise rises and falls, it's not a single instance like a car passing where it passes very quickly or a dog barking even. It's unpredictable. The intensity,... rises and falls. It can be quite thumpy, then it can go quiet, then it can go up and down and so on and so on."


123. Aside from the fact that she views the nuisance as remaining unabated, three features of Ms. Webster's evidence bear emphasiss.


124. First, Ms. Webster is stressed and worried about the wind turbine. She has been worn down by the WTN and finds it increasingly difficult to stay in the house. She is understandably disappointed by the approach to the mitigation process in which the defendant trialled only one different operating mode as part of what was intended to be a "trial and error exercise".


125. I formed the impression that Ms. Webster's disappointment and frustration, justifiable though they may be, now impact her perception and tolerance levels of the WTN. An obvious example of this is Ms. Webster's approach to the issue of audibility of the WTN inside HH. During module 1, Ms. Webster was cross-examined as to whether she equated nuisance with mere audibility internally. The thrust of Ms. Webster's answers was that it was not audibility alone that disturbed her concentration, relaxation and enjoyment and caused her difficulty falling asleep. Rather, it was audibility, combined with low frequency impacts, such as vibration and a sense of pressure. Ms. Webster also relayed being woken "bolt upright" from her sleep by the WTN, which clearly implies a higher level of noise than mere audibility.  I believe that there has been hardening in Ms. Webster's position. She now takes the view that if the turbine is audible at all indoors it is thereby a nuisance. I cannot agree.  One cannot equate audibility, even internally, with nuisance.


126. Second, in cross-examination, counsel for the defendant laid great emphasis upon para. 70 of this court's judgment reciting Ms. Webster's evidence. I stated "what primarily disturbs Ms. Webster's relaxation and sleep is when the turbine is turning "full tilt"". The defendant relied upon Ms. Webster's use of the phrase "full tilt" in two ways;  first it suggests that it is inconsistent with Mr. Stigwood's findings at module 2, that the worst noise intrusion occurs at moderate to higher windspeeds (but not at the highest windspeeds). Second, the defendant maintains that the phrase "full tilt" led it to assume that mitigation was only required at the highest windspeeds, leading it to select the 1,600 mode (which only limits rotational speeds and noise at windspeeds above 7.8 m/s) for the trial and error process.


127. This was an entirely unreasonable position for the defendant to adopt. Ms Webster's use of the phrase "full tilt" cannot justify the defendant's conclusion that the WTN is not a nuisance at windspeeds below the maximum.  Ms. Webster's complaints of intrusive WTN usually occur at night when she is in bed and is clearly not counting turbine blade rotations. Rather, her sense that the turbine is turning fast will be a general impression gained from the rhythm of the noise in her room. Even during the day, Ms. Webster would be unable to count the turbine rotations with the naked eye.


128. In any event, the defendant fails to distinguish between the court's recital of Ms. Webster's evidence at para. 70 and the court's findings. The court did not find that the WTN was most intrusive, still less that it was only intrusive, when the turbine was turning at its very fastest level. Rather, I concluded at para. 631 that whilst this would potentially need to be revisited in module 2, it was likely that the worst features of the WTN were associated with at least "moderately higher speeds of rotation". Similarly, at para. 590, I found that "at moderate to high speeds of rotation" the impact of the WTN far exceeds masking levels and is the primary noise experienced in the environment.


129.  This court's reference to moderate to high windspeeds was based in part on my finding that the WTN at the time of my site visit to the plaintiffs' houses did not give rise to nuisance. Nuisance therefore arises at windspeeds greater than 3.8 m/s to 4.8 m/s. It follows that my reference to moderate to high windspeeds may be interpreted as windspeeds above 5m/s in any event. In addition, the evidence at module 1 was that the turbine reaches its maximum speed of rotation at 9 m/s and that, beyond that, the WTN does not increase with rising wind speeds. Further, at very high windspeeds background wind noise progressively increases masking the WTN.  These factors in themselves imply that any assumption that the greatest problems occur at the very highest windspeeds is misplaced. I also found that the WTN was more intrusive at night time, when ambient background levels are low and stable atmospheric conditions both enhance sound propagation and render high AM values and thump AM more prevalent.


130. Third, Ms. Webster states that on 12th July 2024, the defendant's solicitors wrote to request that audio recording equipment to be placed in her personal bedroom which she would be required to turn on and off in order to record the noise. Ms. Webster states that she was surprised to receive this additional request as it was not part of the mediation agreement which had been signed two weeks earlier. Ms. Webster considered this an intrusive and unnecessary request and did not agree to it.


131. Ms. Webster states that the defendant could have used five other bedrooms in her home for monitoring. There is a dispute between the parties as to whether or not the defendant was willing to carry out monitoring in one of the other bedrooms in the house as a proxy for Ms. Webster's bedroom and, if so, whether she was willing to permit this. The defendant's position is that Ms. Webster refused any internal monitoring. The plaintiffs' position is that internal monitoring was not ruled out, provided it was not in Ms. Webster's bedroom. One way or another, internal monitoring was not agreed at mediation and the plaintiffs were evidently not prepared to depart from the terms of the detailed mediation agreement.


132. It may have been more constructive had Ms. Webster responded to the defendant's letter of 12th July 2024, with a formal counter offer of noise monitoring in another bedroom. However, I attribute any inflexibility to Ms. Webster's increasing frustration over the defendant's general response to her complaints, no doubt copper fastened by its attempt to depart from the monitoring procedures agreed at mediation. In any event, this is largely by the by. The lack of internal monitoring by the defendant in Ms. Webster's bedroom does not prevent this court from deciding the issues which fall for resolution in this module.

 

Evidence of Mr. Stigwood, plaintiffs' acoustician

Misinterpretation of the principal judgment


133. Parts of Mr. Stigwood's module 2 report suggest that he interpreted the principal judgment as holding that the mere presence of high AM values and/or thump AM is sufficient to establish nuisance.


134. Much of Mr. Stigwood's module 2 report focuses on demonstrating high AM values and thump AM, without analysing how these features correlate with overall WTN levels. As a result, in much of the data that Mr. Stigwood presents, AM levels are high (and thump AM is present), but overall noise levels are quite low, particularly when compared to the data previously gathered by Ms. Large.


135. The defendant disputes Mr. Stigwood's interpretation of the principal judgment. I agree with the defendant on this point. This court's conclusion was not that the mere presence of high AM values and thump AM constitutes nuisance. Rather, high AM values are liable to create nuisance if audible at a sufficient level. Similarly, thump AM is liable to constitute nuisance if within the audible range; or if giving rise to unacceptable vibration and pressure (always bearing in mind that low frequency noise can annoy at lower levels). Thus, I found that thump AM, which is both heard and felt, as vibration or as a sense of pressure, was the most intrusive feature of the WTN.


136. However, Mr. Stigwood's testimony did not suffer from this frailty. He accepted that high AM values and thump AM are not per se evidence of nuisance. Overall noise levels must also be taken into account. This is consistent with the court's findings, and with the evidence of Mr. Stigwood and Ms. Large (upon whose testimony the court placed particular emphasis) in module 1.

 

Has the 1,600 mode abated the nuisance?


137. Mr. Stigwood's analysis of the WTN in the 1,600 mode is set out in a lengthy report running to almost 100 pages containing almost 100 different time-domain graphs and other graphs. His evidence is that the 1,600 mode, does not result in the abatement or improvement of the nuisance. Intrusive AM continues externally and internally, [27] including at nighttime, in the evenings and weekends.


138. Mr. Stigwood states that, in the 1,600 mode, high AM values are measured on the time-domain graphs and on the application of the IOA RM. Several of these time-domain graphs showed AM values of 10 dB, the highest possible value using the IOA RM. IOA RM analysis shows that high AM values are associated with at least moderately high speeds of rotation (as opposed to the highest rotational speeds).  AM values are highest at windspeeds between 5.1 and 8.7 m/s, and are maximal at 7m/s approximately.


139. Unconstrained, maximum T2 rotations are in the order of 22 or 23 rotations per minute. The 1,600 mode caps turbine rotations at 18.6 revolutions per minute. It does not therefore "kick in" until revolutions have reached that speed and only starts to have an effect when windspeeds are in excess of 8 m/s.


140. When visiting HH during the mitigation trial, Mr. Stigwood experienced erratic, dominant and impulsive WTN externally and internally. He correlated his experience (and that of Ms. Webster) with the raw data noise collected and with the SCADA data, and found that same concurred.


141. By listening to the WTN and correlating it with the spectrograph, Mr. Stigwood  concluded that thump AM is dominant for substantial periods and is particularly prominent internally. In Mr. Stigwood's opinion, thump AM remains the primary cause of nuisance even in the 1,600 mode. This thump AM is worst under conditions of meteorological stability, which most often occurs at windspeeds below those at which the cap applies.


142. Mr. Stigwood summarises his view on the 1,600 mode as follows: "in a short few words, the cap has not stopped the AM and its exceedance over the background, its dominance, its erraticism, its intermittency, the impulsive character, all those elements within it, its excessive AM values, it hasn't stopped any of those. So the cap has not prevented these occurring. They have continued to occur."


143. Mr. Stigwood's uncontradicted evidence is that Mr. Carr's 2024 1,600 mode noise monitoring data demonstrates noise levels 2 to 3 dB lower than his own data. This must be taken into account in interpreting Table 3.   


144. Unlike Mr. Carr, Mr. Stigwood presents a full IOA RM analysis of the WTN during the mitigation mode. Although this provides the court with some of the important data omitted from Mr. Carr's reporting, as Mr. Stigwood uses Mr. Carr's 2024 raw noise data for this IOA RM analysis, the data set is necessarily incomplete for the reasons just explained.


145. Fortunately, it is not necessary to grapple with the minutiae of this analysis in order to determine whether or not the 1,600 mode has abated the nuisance. This is because two things are common case: First, AM values and thump AM  are not impacted per se by the 1,600 mode (or in all likelihood by any of the operation modes). Second, the impact of the 1,600 mode is to reduce WTN by a maximum of 2.1 dB at windspeeds of 9 m/s and above. At windspeeds of 3 m/s and 4 m/s, the 1,600 mode brings about no change in WTN noise levels. At 5 m/s, it actually increases WTN by slightly less than a decibel. At 6 m/s, 7 m/s and 8 m/s the 1600 mode is estimated to reduce WTN by between .8 and 1.2 dB.


146. It is common case that, from the perspective of one listening to the WTN,  a noise level change of 3 dB is on the boundary of perception and that a change of 2.1 dB is either barely perceptible or imperceptible. Therefore, as the 1,600 mode has effected no improvement in AM values or thump AM and has merely reduced noise levels to an effectively imperceptible degree, it could not be expected to ameliorate the nuisance to an appreciable extent.

 

The IEC


147. Mr. Stigwood was unimpressed by the defendant's use of the IEC which he said had not been adopted in Ireland. He disagreed with the proposition that the IEC represented a significant change in the assessment of thump AM. The only way to differentiate between swish and thump AM is to look at the spectrum data. Mr. Stigwood was also critical of the defendant's failure to apply Appendix C of the IEC, which deals with low frequency noise evaluation.

 

Other evidence from Mr. Stigwood relevant to the potential abatement orders this court might make


148. Mr. Stigwood's view is that it is not for the plaintiffs to suggest mitigation measures for the wind turbine. However, in most cases of intrusive AM, turbine shut down at sensitive times is required.


149. Mr. Stigwood criticised the defendant for seizing upon Ms. Webster's comment that the turbine most disturbed her when it was spinning "full tilt" and then trialling a cap that only kicked in at the highest windspeeds. In his view, the blades rotate quickly at windspeeds of 6 m/s and up. Mr. Stigwood states that an observer would not visually perceive a difference between rotational speeds at, say 6 m/s and 9m/s. Both could in his view fairly be described as "full tilt." It is preposterous to expect an observer to reliably discriminate between turbine rotational speeds of 16.33 revolutions per minute (RPM) at windspeeds of approximately 6m/s and 18.59 RPM at windspeeds of approximately 9m/s. As there are three blades, the difference in blade passing frequency between these two windspeeds will not be apparent to the naked eye. I agree.


150. The defendant relies upon data from the turbine manufacturer, Enercon, which predicts likely reductions in WTN at different windspeeds in a range of different operational modes ("the Enercon prediction data"). Mr. Stigwood notes that the predicted noise level reductions are averaged out over all wind directions. The predicted reductions cannot therefore be assured in any particular wind direction. Further, the predictions are based on measurements taken very close to wind turbines in unstable meteorological conditions. In Mr. Stigwood's view, the predicted noise level reductions may not therefore be achieved, particularly at night when meteorological conditions are stable and wind shear is high. On the other hand, Mr. Stigwood appears to accept that the 2024 1,600 mode noise monitoring does demonstrate WTN level reduction in the broad range predicated by Enercon (when averaged over 24 hours and in all wind directions).


151. The most adverse impact of the WTN occurs when rotations are moderate to high, which he defined as windspeeds of above 6 or 7 m/s. High AM values and thump AM virtually disappear at very high windspeeds, which he defined at above 12 m/s. At windspeeds above 12m/s, WTN is a rumbling type of noise with very little character which is less intrusive, particularly in the presence of other masking noises, such as wind noise. The exception would be when there are extremely stable atmospheric conditions.


152. Generally wind direction can make a big difference to AM and WTN levels. However, Mr. Stigwood stated this was not necessarily the case on Mr. Carr's spiderweb graphs, particularly in crosswind conditions.


153. Mr. Stigwood acknowledges that restricting the operation of T2 to its lowest power mode of 1,000 KW ("the 1,000 mode") could potentially provide a noticeable difference to overall sound levels. However, this may not ameliorate intrusive AM. I have some difficulty with this. The ETSU Review, notes a strong association between the annoyance posed by AM and the absolute sound level of the WTN. In my view, therefore, it is generally safe to assume that a noticeable reduction in  noise levels will have an appreciable beneficial impact. This is of relevance in crafting fair and proportionate injunctive orders.

 

Evidence of Mr. Mayer, Mechanical and Automotive engineer


154. Mr. Mayer who operates as a Wind Energy Consultant advising on the execution of wind development, states that noise mitigation is well established in the wind industry due to complaints of noise nuisance caused by technical failure, inadequate distance, or irregularities in wind flow. Mr. Mayer considers that the mitigation exercise undertaken by the defendant was a poorly structured process and lacked the required professionalism and expert input.  The adoption of a single alternative mode for T2 during a two month period is inadequate. Mitigation ought continue for at least six months.


155. Mr. Mayer criticised Mr. Brazil's failure to consult in detail with Enercon prior to commencing the mitigation process.  If this court's judgment had been discussed with Enercon, it could have devised a tailored and effective mitigation process. The turbine can be programmed to trigger a wide range of noise reduction modes to mitigate specific noise generating constellations of wind speed and wind direction whenever they appear.


156. In addition to offering different operating modes, further mitigation could have been achieved by modalities such as trailing edge serrations, blade feathering and other mechanical or electrical interventions.

Defendant's evidence

Evidence of Mr. Brazil


157. Mr. Brazil's evidence was that the new IEC was applied to the 2017 NF data to obtain a thorough description of the sound characteristics of the WTN when operating in the 2,300 mode with a view to this data providing a starting point for mitigation purposes. In his oral evidence, Mr. Brazil referred to Mr. Carr's spiderweb graphs as derived from the 2017 NF data but not to any further data and in particular not to the Carr comparative exercise.


158. Mr. Brazil gave evidence that "there is  meaningful [noise] reductions in my opinion". He did not, however explain how he had reached this conclusion.

 

Evidence of Mr. Carr, defendant's acoustician


159. The primary purpose of Mr. Carr's report and statement was to set out his comparative exercise which he contends shows that there is no nuisance in either the 2,300 mode or the 1,600 mode and that no mitigation is required.


160. Mr. Carr carried out an AM assessment of the 2017 NF data and the 2024 1,600 mode data. He sets out the results in several graphs. As I have decided to admit only the 2024 1,600 mode data, only those graphs are relevant. Further, it is not disputed that the noise levels for the front garden are elevated as compared to the rear garden due to external sounds, I will focus on the rear garden 2024 1,600 mode data.


161. I reproduce below figures 5 and 6 of Mr. Carr's report. These are the spiderweb graphs analysing the rear garden 2024 1,600 mode data pursuant to IOA RM/IEC. Figure 5 presents results for the rear garden on a 24 hour "all data" basis and figure 6 presents the results for nighttime. [28]These graphs set out derived AM penalties rather than AM values per 10 minute segment, as would generally be required. Figures 5 and 6 shows a significant number of AM penalties of 4 to 5 dB, indicating AM values between 6.5 dB and 10dB and AM values above 10 dB, respectively. I also reproduce Table 3 which sets out the comparative exercise for the rear garden 2024 1,600 data at night time [29] in the downwind direction only.

Figure 5: IOA RM results - 2024 1,600 rear garden 24 hour data  

Figure 6: IOA RM results - 2024 1,600 mode rear garden night-time (23:00 to 07:00hrs) data

 

Table 3  2024 1,600 mode rear garden 23:00 to 04:00hrs data- downwind only

 

Wind Speed m/s

Total measured noise level LA90,dB

Total measured noise level LA90,dB + AM Penalty

Difference (dB)

4

25

29

4

5

30

34

4

6

34

38

4

7

36

40

4

8

37

41

4

9

38

41

3

10

38

41

3

11

38

41

3

12

39

41

2

 


162. Mr. Stigwood did not quibble with the penalties derived by Mr. Carr or with Table 3. For this reason, I will accept that, save for a potential underestimation of sound levels by 2 or 3 dB, the data summarised at Table 3 is accurate. Table 3 shows that AM values are at their highest at windspeeds of 4 to 8 m/s. AM values drop at windspeeds of 9m/s to 11 m/s and drop again at windspeeds of 12 m/s. The acoustic experts therefore agree that AM values are highest at windspeeds below the level at which the cap becomes fully operational.


163. Mr. Carr states that the downwind sector, [30] when the wind is blowing from the turbine to the receptor location, generates the loudest noise. He contends that the crosswind and upwind sectors produce lower levels of WTN at HH. He does not however present any data which would inform the court as to noise levels in the crosswind and upwind sectors.


164. This is an unfortunate and significant omission from the defendant's perspective. It means that the court can only apply the broadest discrimination between different wind directions in setting abatement measures. [31]


165. Mr. Carr's evidence is that having examined Ms. Webster's diary entries and Mr. Stigwood's report, there is no obvious pattern to any specific wind speed or direction that can be correlated with the AM complaints set out in the noise diaries.


166. In cross examination, Mr. Carr did not agree that, rather than looking at averages, nuisance is concerned with the minute by minute experience of the plaintiffs. He denied that this experience is better illustrated on the time-domain graphs than by the averages presented in his reports. He agreed however that the IOA RM cannot tell one what the noise sounds like and that it does not differentiate between swish and thump AM.


167. Mr. Carr accepted that his report omits important data which the IEC requires to be reported, such as average 10 minute AM values and the percentage of 3dB modulation depths, 6dB modulation depths and 9 dB modulation depths in the data presented. Mr. Carr's data informs the court only of average AM penalties per windspeed. I cannot know what makes up those averages. The penalty averages may be the mean of very high and very low AM penalties over 10 minute periods or they may represent the most commonly occurring penalty. This omitted information would be highly relevant in determining the specific circumstances under which high AM values may give rise to nuisance at HH. Although the defendant argues that Mr. Stigwood's "compliant" IOA RM analysis fills this lacuna, the lacuna is entirely unsatisfactory in the first place.


168. Both experts are agreed that because the IEC essentially adopts the IOA RM methodology, very high AM values would not be reflected in the data unless present for more than 50% of any particular 10 minute block.  This inexorably means that a greater number of short, intermittent episodes of high AM values will be experienced on site than are reflected in Mr. Carr's analysis. His data is liable to significantly under-represent Ms. Webster's lived experience of high AM values on a day to day basis.


169. Mr. Carr maintains that the average modulation depth for the mitigation period was approximately 3 or 4dB. This may well be correct. However, this is an average for all windspeeds and all wind directions. Even leaving aside low frequency/thump AM, emergence, etc, this in no way forecloses nuisance at times when AM values are greater than this, which the evidence shows is a common and regular occurrence.


170. Mr. Carr's opinion on whether the 1,600 mode has abated the nuisance is so inconsistent as to be meaningless. He accepted that reducing the power mode does not reduce AM values or thump AM per se and that effective abatement can only be achieved through overall noise reduction. He then supported the defendant's contention that the maximum noise reduction of  2.1 dB effected by the 1,600  mode was "significant" and not "negligible". However, he also accepted that, from the point of view of one listening to the WTN (a "receiver"),  a noise level reduction of 3 dB would be on the very boundary of perception. I cannot reconcile these two positions and nor, I suspect, can Mr. Carr.

Has the 1,600 mode abated the nuisance? Onus of proof


171. As the defendant submits, the burden of proof in relation to nuisance rests with the plaintiffs. In Hanrahan v. Merck Sharp and Dohme (Ireland) Ltd [1988] ILRM 629, the Supreme Court found that it "would be contrary to authority" to require the defendants to disprove that the plaintiffs had suffered the mischief complained of or that same was caused by emissions from its factory. In the present case, this burden has already been discharged in relation to the 2,300 mode and the court has ruled on liability.


172. There is a dispute between the parties as to who bears the onus of proof on the question of whether the 1,600 mode has abated the nuisance. The plaintiffs maintain that the onus of proof is on the defendant and the defendant maintains that the contrary is the case. I accept the plaintiffs' submission on this point. The plaintiffs have proved, on the balance of probabilities, that the WTN is a nuisance. It is not necessary for them to prove this again and again for each adjustment to the turbine that the defendant might choose to make. Rather, the onus is on the defendant to prove that the adjustment that it proposes, the 1,600 mode, abates the nuisance.

Findings of fact regarding the 1,600 mode  


173. In the principal judgment I was satisfied that:  

1.    The WTN is a nuisance at night [32] and during the quiet waking hours. [33]

2.    Adverse impact occurs at windspeeds in excess of those which prevailed at the time of the court's visit (i.e. at windspeeds in excess of 5m/s).

3.    Albeit that it would potentially require to be re-visited in module 2, it is likely that the worst features of high AM values and thump AM are associated with at least moderately higher speeds of rotation when WTN levels are sufficient to bring these characteristics to the fore.


174. On the basis of the evidence adduced at module 2, I now make the following findings of fact:

1.    Table 3 shows that in the 1,600 mode, average night time downwind AM penalties at windspeeds between 4 and 8 m/s are 4 dB. Average night time downwind AM values are therefore between approximately 6.5 and 10 dBs. However, these penalties are averaged over several weeks. In any event, the IOA RM only captures those high AM values which are present for more than 50% of any 10 minute period. I am therefore satisfied that there are also regular periods of higher AM values at these windspeeds.

2.    In the 1,600 mode, average night time downwind AM penalties at windspeeds of  between 9 m/s and 11 m/s are 3dB. Average night time downwind AM values are therefore  between 3 dB and approximately 6.5 dB. However, by the same logic, I find that there are also regular periods of higher AM values at these windspeeds.

3.    Thump AM continues to be a regular feature in the 1,600 mode. This has been confirmed by spectrograph analysis.

4.    In the 1,600 mode, erraticism, impulsivity, unpredictability and dominance continue as before.

5.    I find on the balance of probabilities that, in the 1,600 mode, the WTN continues to disturb Ms. Webster's concentration, relaxation, enjoyment of her home and sleep to an unreasonable extent.


175. As will be evident, it is not even necessary to rely on the onus of proof to conclude that the 1,600 mode does not abate the nuisance. It is common case that, from a receiver's point of view,  a noise level change of 3 dB is on the boundary of perception and that a change of 2.1 dB is barely perceptible or imperceptible. It is also common case that the 1,600 mode has effected no change to AM values, thump AM and other intrusive features such as erraticism, impulsivity, unpredictability, etc. A maximum reduction in WTN of 2.1 dB will not abate WTN nuisance arising from high AM values, thump AM, erraticism, impulsivity and unpredictability, which together dominate the plaintiffs' noise environment.


176. I therefore find as a fact, on the balance of probabilities, that the 1,600 mode does not ameliorate the nuisance to any appreciable extent. The defendant suggests that it had insufficient time for the mitigation exercise. Its written submissions note that on 2nd July 2024, prior to the trial and error process commencing, senior counsel for the plaintiffs applied for a hearing date for module 2. The defendant now submits that, despite objections raised by its counsel, who argued that more time was required, this court directed a November 2024 hearing date. This is a mischaracterisation of what occurred on 2nd July 2024. The mediation agreement, which was before the court on 2nd July 2024, specifies that the mitigation exercise terminate by September 2024. The defendant did not request the plaintiffs or the court to extend the mitigation period for the purposes of trialling other potential turbine modes. Rather, counsel contended that as the mitigation exercise would not be completed until September 2024,  the defendant would not be ready for the trial of module 2 until the New Year of 2025. This, I regarded as being an excessive delay.

Analysis and findings of fact relevant to the potential abatement orders this court might make


177. Citing Lanigan. v Barry [2016] 1 IR 656 ("Lanigan"), the defendant argues that there are insufficient findings of fact in the principal judgment to determine the appropriate form of injunction. This requires some explanation.  In Lanigan, the High Court had determined that a significant increase in activity at a motor racing circuit since its grant of planning permission amounted to a material change of use, meriting an injunction pursuant to s. 160 of the Planning and Development Act 2000. The trial judge also found that the motor racing circuit caused a noise nuisance to the plaintiff's neighboring stud farm also meriting an injunction. The trial judge  granted an injunction on both grounds significantly restricting the operation of the motor circuit. The injunction was principally focused on bringing the situation back to that authorised by the planning permission as interpreted by the trial judge. On appeal, it was contended that the injunction was excessive. The Supreme Court found that the trial judge had failed to have regard to the fact that some of the intensification, held to be a material change of use, was immune from enforcement as same was statute barred. As such, the s. 160 injunction could not stand. Further, because the High Court's injunction for nuisance was simply a reproduction of the planning injunction, it was also set aside. The Supreme Court also held that it could not determine the precise form of planning injunction to be granted in the absence of clear findings of fact regarding the level of use before and after the expiry of the enforcement limitation period. Likewise, in respect of the case in nuisance, the Supreme Court determined that there were insufficient findings of fact to allow it to craft an appropriate injunction designed to do justice in all of the circumstances.


178. In remitting the matter to the High Court, Clarke J. stated at para. 48: 

 "While the findings of fact sufficient to establish that there is a nuisance cannot, therefore, be disturbed, there are, in my view, insufficient findings of fact to allow this court to craft an appropriate form of injunction designed to do justice in all the circumstances pertaining to the nuisance claim. That is not to say that some form of injunction will not, almost inevitably, follow in order to deal with the established nuisance. However, this court does not have sufficient definitive findings of fact to enable a decision to be made as to the precise form in which any such injunction should be imposed."


179. The key point is that this lacuna arose because the trial judge had formulated the injunctive relief for nuisance largely by reference to the planning permission. There were therefore few findings of fact which could inform the appropriate injunction to grant solely in respect of nuisance.


180. The present case is distinguishable. This court has determined on the basis of extensive findings of fact that the WTN poses a nuisance to the plaintiffs at specific times of the day and night and has explained why. It stands to reason that the conditions giving rise to nuisance such as moderate to high windspeeds, stable atmospheric conditions and high windshear will occur on an intermittent basis, albeit regularly and for sustained periods during these sensitive periods. When such conditions occur, nuisance arises in the manner already described.


181. The defendant submits that "it is not open or appropriate for this court to determine the precise form of injunction that should be granted in the absence of definitive findings of fact as to where the threshold for nuisance lies, or when and under what circumstances the nuisance occurs". Effectively, it argues that before granting an injunction, the court must (1) prescribe the precise combination of WTN decibel level and AM value that amounts to WTN nuisance and (2) must determine the precise combination of wind speed, wind direction and metrological conditions that render the Ballyduff WTN liable to cause a nuisance.  I disagree.


182. The defendant's approach is simplistic and reductive of this court's findings at module 1. The WTN nuisance is not a product only of the WTN decibel level and its AM values. All of the "Defra factors" considered in the principal judgment are crucial to the assessment. It is neither necessary, nor indeed even possible, for this court to adjudicate upon the scientific and acoustic causes of the WTN nuisance in this case, particularly not to the level of detail insisted upon by the defendant. Naturally, WTN nuisance caused by the interaction of the blades with the atmosphere and the environment will not be constant. It will wax and wane. Nor will the impact be wholly consistent at a given windspeed and wind direction.


183. In short, because the existence and cause of the WTN nuisance in this case is multifactorial, this court cannot prescribe the precise combination of WTN decibel level and AM values at which it is or is not a nuisance. Still less can it determine the precise combination of wind speed, wind direction and metrological conditions that render the Ballyduff WTN liable to cause a nuisance.


184. However, I can and have determined that, as presently operated the WTN causes a nuisance to the plaintiffs on a regular basis, for sustained periods of time, many of which correspond with the most sensitive times of the day.


185. The defendant must bear the onus of proof in demonstrating that the WTN does not give rise to a nuisance at particular windspeeds or in particular wind directions. It is for the defendant to bring forward evidence on foot of which I can carve out particular windspeeds or particular wind directions as being unlikely, on the balance of probabilities, to cause nuisance. In so far as there is insufficient evidence to carve out particular windspeeds or particular wind directions, it is also for the defendant to bring forward evidence to demonstrate that particular mitigation measures, such as a specified reduced power mode, will reliably and consistently abate the WTN nuisance and that shut down is not necessary at those particular windspeeds or particular wind directions. Insofar as the defendant has not brought forward such evidence, the court will make such findings of fact as are open to it on foot of the other evidence in the case.  


186. Bearing all of the above in mind, and on the basis of the evidence of both parties adduced at module 1 and module 2, I now make the following findings of fact of relevance to potential abatement orders:

1.    The WTN is most intrusive at moderate to high windspeeds of 5m/s to 8 m/s. I draw this conclusion for a number of reasons. First, as explained at para. 129 above, the WTN does not pose a nuisance at windspeeds below 5m/s. Although high AM values and even thump AM may occur at these low windspeeds, the WTN level is low enough that such features are not liable to annoy. In the second place, Mr. Carr's 2024 1,600 mode data shows that at night time, windspeeds of 5 m/s to 8 m/s are associated with the highest AM values which is widely recognised to be intrusive if audible at a sufficient level. As it is common case that the 1,600 mode has effected no change to AM values (or indeed to thump AM, erraticism, impulsivity, unpredictability, etc), this conclusion applies equally to the 2,300 mode. In the third place, thump AM is more likely to be noticeable when combined with these high AM values. Fourth, thump AM is more prevalent under conditions of meteorological stability, which most often occur at windspeeds below 8 m/s. Fifth, at these windspeeds, background masking levels in the form of wind noise will be low when compared to higher windspeeds. I therefore find that the WTN gives rise to nuisance at windspeeds of 5m/s to 8m/s and that this occurs intermittently but commonly, and for sustained periods, throughout quiet waking hours and at night.

2.    At windspeeds of 9m/s, high AM values and thump AM also occur intermittently but regularly and for sustained periods. I accept that this causes a nuisance during quiet waking hours and at night. I draw this conclusion for a number of reasons. First, Mr. Carr's Table 3 shows that at a windspeed of 9m/s, average downwind night time AM penalties are 3 dB. At 9m/s average AM values are thus between 3 and 6.5 dB.  Second, in light of the limitations of averaging and given that the IOA RM analysis will not reliably capture erratic or intermittent high AM values, I find that there are also regular and sustained periods of higher AM values at windspeeds of 9m/s. Third, I accept Mr Stigwood's evidence that thump AM regularly accompanies these high AM values. Fourth, I find stable atmospheric conditions, which occur most frequently at night, further exacerbate WTN nuisance. Fifth, I accept Mr. Stigwood's uncontradicted evidence that modern thinking now considers that high AM values and thump AM are more likely to disturb sleep when occurring with rapidity, which is a feature of higher rotational blade speeds caused by higher windspeeds, such as 9m/s. Overall, at a windspeed of 9m/s,  high  AM values and thump AM, causing vibration and pressure, occur with frequency and rapidity (in the sense just described). There features combine with the emergence of the WTN over background noise, and its erraticism, impulsivity and unpredictability, to dominate the sound environment on an intermittent but regular basis.

3.    Table 3 presents average AM penalties of 3 dB at windspeeds of 10 m/s and 11 m/s in the 1,600 mode. As it is accepted that the 1,600 mode has not impacted AM values (or thump AM), the same AM values should broadly apply to the 2,300 mode. [34] Therefore, at windspeeds of 10 m/s and 11 m/s average AM values are between 3 and 6.5 dB.  Thump AM regularly accompanies these  high AM values. Although, at these higher windspeeds of 10 m/s and 11 m/s, AM and thump AM will be less intrusive due to the masking effect of wind noise, in very stable atmospheric conditions, sleep will still be disturbed. This, in turn, is due to at least three factors: the rapidity of blade rotation, the  fact that thump AM will be more prevalent internally than externally and the fact that masking wind noise will be less effective internally than externally.  I therefore find that the WTN is liable to give rise to nuisance in the form of sleep disturbance at night and in the early morning on an intermittent but regular basis at windspeeds of 10 m/s and 11 m/s. On the other hand, I do not find nuisance is likely to arise during quiet waking hours at windspeeds of 10m/s and 11 m/s.

4.    At the very highest windspeeds (which Mr. Stigwood puts at 12m/s and above), high AM values, thump AM and the other features of the WTN will be even less common. Masking wind noise will be of considerable benefit at windspeeds of 12m/s and above.  However, WTN nuisance will still arise, albeit on a fairly intermittent basis in very stable atmospheric conditions at night and in the early morning. I do not find that nuisance is likely to arise quiet waking hours at windspeeds of 12m/s and above.

5.    Figure 5 shows that in the 1,600 mode,  high day time AM values (i.e. AM values which would attract penalties of 3 to 5 dB) occur in all wind directions bar the 135 to 180 degree sector. Figure 6 shows that in the 1,600 mode, high night time AM values occur in all wind directions bar the 90 to 180 degree sector. This applies equally to the 2,300 mode.

6.    Other than as indicated at point 6 above, high AM values can occur in all wind directions.

7.    Despite the limitations of averaging and accepting that the IOA RM will not capture high AM values if present for even as much as 49% of a particular 10 minute period, it is reasonable to conclude that if figures 5 and 6 show virtually no high AM values in a given wind direction, then same are unlikely to be a substantial or regular feature of the WTN in that particular wind direction.

8.    As Mr. Stigwood's evidence was that thump AM accompanies high AM values, I also conclude that, when AM values are low, thump AM is unlikely to cause a nuisance.

9.    The features giving rise to WTN nuisance in this case go well beyond mere high AM values. However, I am satisfied that where the data shows no (or virtually no) high AM values in a particular wind direction, then nuisance can on the balance of probabilities be excluded in that wind direction. As such, I am satisfied that nuisance does not occur, in the 1600 mode, the 2,300 mode or in any other operational mode during quiet waking hours in the 135 to 180 wind direction or during the night in the 90 to 180 wind direction.


10.  Although noise levels are generally likely to be lower in crosswind and more particularly upwind directions, the defendant has not provided any evidence on which I could determine how much lower WTN levels might be.


11.  I find that, although there is clearly a margin of error, the noise level reductions that Enercon predicts for different operational modes should be broadly achievable during the day. However, due to stable meteorological conditions, such an outcome is uncertain at night. In the absence of evidence to verify that these predictions can  consistently be achieved at night, I cannot be so satisfied.

Are the plaintiffs entitled to an injunction?


187. The plaintiffs submit that the appropriate remedy is an injunction restraining the operation of T2 such that it does not cause noise nuisance at HH. 


188. In Lawrence v. Fen Tigers Ltd [2014] 2 All ER 622 at para.121, Lord Neuberger stated that once nuisance has been established "the prima facie position is that an injunction should be granted, so the legal burden is on the defendant to show why it should not".  Likewise, in Patterson v. Murphy [1978] ILRM 85, Costello J. stated that when an infringement of the plaintiffs' rights and further threatened infringement have been established, the plaintiffs are prima facie entitled to an injunction of which they will only be deprived of "in very exceptional circumstances". He then stated, echoing Shelfer v. City of London Electric Company [1895] l Ch 287, as follows:

"If the injury to the plaintiffs' rights is small, and is one capable of being estimated in money, and is one which can be adequately compensated by a small money payment, and if the case is one in which it would be oppressive to the defendant to grant an injunction, then these are circumstances in which damages in lieu of an injunction may be granted.

The conduct of the plaintiff may be such as to disentitle him to an injunction.  The conduct of the defendant may be such as to disentitle him from seeking the substitution of damages for an injunction.

The mere fact that a wrong-doer is able and willing to pay for the injury he has inflicted is not a ground for substituting damages."


189. Although it is maintaining the position that there is mitigation at 1600 mode wind speeds, it appears that the defendant is now offering no suggestion of mitigation to the court. Rather, it adopts the primary position that mitigation is not required because nuisance is not established. It appears to contemplate no further adjustment to T2 unless mandated by the court. It also maintains that the plaintiffs ought to be confined to damages in lieu on the application of the Shelfer principles. It is clear that the nuisance will therefore continue if not interrupted by an order of this court.


190. The plaintiffs contend that their injury is not "small" or capable of being compensated by a "small" award.  The defendant contends that damages are "easily quantifiable at this point". However, perhaps because quantum of damages is not for determination in this judgment, it goes no further than that and does not actually submit that such damages would be "small".


191. I am satisfied that the injury to the plaintiffs is not "small" in the sense described above by Costello J. Ms. Webster and Mr. Rollo's home life has been very seriously impacted by the nuisance and Mr. Rollo now lives away from their home.  The noise seriously intrudes on Ms. Webster's enjoyment of her home; she is deprived of the healthy and comfortable enjoyment of her home and her sleep is disrupted. 


192. As regards the conduct of the parties, the defendant submits that it has at all times acted in good faith in the hope of resolving the dispute between the parties.  The plaintiffs maintain that the defendant's conduct was cynical in the extreme because:

·         The defendant did not engage in any serious effort at mitigation, but rather used the opportunity presented to it by the court to adduce new evidence to dispute this court's finding on liability.

·         Despite only reducing nuisance by a level now acknowledged to be barely perceptible or imperceptible from a receiver's point of view, the defendant maintained that the 1,600 mode had abated the nuisance. Mr. Brazil gave evidence to this effect. The defendant robustly cross-examined Ms. Webster on this premise.  Only at the conclusion of the hearing was it apparently conceded that the mitigation had "not changed anything appreciable" .


193. I agree that aspects of the defendant's conduct are unimpressive. However, I interpret this behaviour as indicative of the defendant's deeply entrenched positions rather than as "conduct which disentitles [it] from seeking the substitution of damages for an injunction".


194. The defendant cites the following passage from Lawrence & Anor v. Fen Tigers Ltd & Ors [2014] 2 All ER 622, in which Lord Neuberger stated, inter alia, as follows:  

 "I would cautiously (in the light of the fact that each case turns on its facts) approve the observations of Lord MacNaghten in Colls [1904] AC 179, 193, where he said:

... if there is really a question as to whether the obstruction is legal or not, and if the defendant has acted fairly and not in an unneighbourly spirit, I am disposed to think that the Court ought to incline to damages rather than to an injunction.."

... If, as I suspect, Lord MacNaghten was simply suggesting that, if there was no prejudice to a claimant other than the bare fact of an interference with her rights, and there was no other ground for granting an injunction, I agree with him."


195. These considerations cannot avail the defendant. Even if I were convinced that the defendant had "acted fairly and not in an unneighbourly spirit," which I am not, the WTN nuisance in this case involves far more than an intrusion on a bare legal right. It has, for a period of seven years, utterly deprived the plaintiffs of the enjoyment of their property.


196. The defendant submits that the potential financial implications render an injunction oppressive and disproportionate. Such a submission requires substantiation by evidence. The defendant failed to adduce any evidence to assist the court in understanding the financial implications of operating in a lower power mode or of turbine shut down at sensitive periods.


197. The defendant has failed to respond to the plaintiffs' legitimate complaints for many years. Ultimately, in response to this court's principal judgment, it has implemented a "mitigation strategy" that, had any thought been given to the matter, was always bound to fail.


198. I am also satisfied that this degree of intrusion on a family home may not fairly be compensated by monetary compensation alone. In Patterson v. Murphy, Costello J. indicated that "the mere fact that a wrongdoer is able and willing to pay for the injury he has inflicted is not a ground for substituting damages". To confine the plaintiffs to damages in lieu would be to permit substantial WTN nuisance   to continue for many more years. This would not do justice between the parties.  On the basis of my findings of fact above, and applying the Shelfer principles, the plaintiffs have made out an entitlement to an injunctive remedy.

Relevance of the public interest


199. The plaintiffs do not seek an order shutting down the turbines completely, but rather an order shutting down T2 during quiet waking hours and night hours.  They submit that such an injunction would not be overly oppressive.


200. The defendant argues that, in considering what remedy to award, I ought to place weight upon the public interest in clean renewable energy. The plaintiffs do not accept that the public interest is of particular relevance to the matters falling for adjudication. They observe that the public interest is not referenced in the Shelfer principles. However, as noted by Lord Legatt in Fearn and others v. Board of Trustees of the Tate Gallery [2023] UKSC 4, ("Fearn"), there had been a move away from "the strict criteria derived from of Shelfer". Ultimately, departure from the Shelfer principles, on grounds of public interest or otherwise, is to be determined by the courts on a case by case basis.


201. The plaintiffs also refer to Bellew v. Cement Ltd [1948] IR 61 in which Maguire C.J. found (at p. 64) that the court was "not entitled to take the public convenience into consideration when dealing with the rights of private parties". However, I note that, in the same case, Black J. took a different view and held that although public convenience cannot affect the right of a private individual to a remedy for nuisance, it can be considered in determining which remedies should be granted. Furthermore, in Patterson v. Murphy, Costello J. acknowledged (pp. 99-100) that the public interest was to be taken into consideration (albeit that he found that none arose in the case before him).  


202. In my principal judgment I stated:

"Although a plaintiff who establishes nuisance has a prima facie right to an injunction such that the defendant bears the legal burden of demonstrating that damages rather than an injunction is an appropriate remedy, the public interest must inevitably be a factor in the court's assessment of an appropriate remedy. At the very least it means that a generalised injunction ought not to be granted where a tailored injunction more suitable to the particular interference held to constitute nuisance is warranted."


203. The plaintiffs concede that this passage is consistent with Fearn in which it was held that whilst public interest considerations are not relevant to liability in nuisance cases, they might be relevant to remedy. 


204. I accept therefore that property rights may need to be balanced with the activity of the defendant, where that activity is in the public interest.  On the other hand, because it is widely recognised that WTN may unreasonably interfere with the amenity of local residents, there is also a public interest in acknowledging and constructively addressing such problems at a national and an individual level. Devising appropriate measures to avoid WTN nuisance at the planning and development stage is clearly of critical importance to the achievement of the State's aim of substantially increasing renewable energy. However, it is also critically important that turbine operators engage constructively with genuine WTN nuisance complaints and devise appropriate abatement measures. I accept Mr. Mayer's view that acoustic experts, engineers and turbine manufacturers such as Enercon, would have a wealth of experience in such matters that the defendant could have leveraged, had it chosen to do so. It was within the defendant's purview to propose a strategy that would abate the nuisance, whilst preserving power generation as much as possible


205. The defendant's argument of public interest based on loss of the environmental benefit of renewable energy is made in the most general terms only. No specific evidence has been provided as to how much of the power produced by T2 at night is actually deployed to the national grid.


206. Notwithstanding, it cannot be denied that that restricting the power output from T2 will inevitably reduce the renewable energy it produces. Accordingly, if I can be satisfied on the balance of probabilities, that measures short of the complete shutdown of T2 during quiet waking hours and night hours would abate the nuisance, then I will fashion a remedy in those terms. Ultimately, for the reasons set out below, I am so satisfied and this court's injunction is crafted accordingly.

Crafting the injunction


207. In Lanigan, Clarke J. stated, that where nuisance is established, the court should adopt whatever remedy appears just in all the circumstances of the case having regard to the need to protect those who suffer by virtue of the nuisance to whatever extent might be considered just and reasonable. He emphasised that planning permission for an activity does not permit the commission of a civil wrong. The injunctive relief which may be justified for nuisance purposes may, either generally or in a specific respect, go further than that which might be justified on planning grounds. The two jurisdictions are not coextensive.


208. Because WTN nuisance will wax and wane with prevailing meteorological conditions an injunction which either shuts down or restricts the operation of T2 will unavoidably be too broad at certain times and too narrow at others. For this reason,  the parties were encouraged to investigate these issues and to proceed by trial and error. Unfortunately, this was a fruitless endeavor.


209. Before explaining how I have crafted the abatement order, it is necessary to make three  preliminary observations:


210. First, the defendant's position is that that AM values and thump AM cannot be controlled or lessened by any engineering or mechanical alterations to the turbine. I am surprised that the defendant did not investigate the improvements that trailing edge serrations, blade feathering or other mechanical or electrical interventions could bring about in the WTN. I am also surprised it made no effort to investigate the meteorological conditions under which high AM values and thump AM manifest with a view to seeking Enercon's advice on how best to abate the WTN. Be that as it may, that opportunity has now passed.


211. As matters stand therefore, short of turning off T2 at sensitive times, the only potential abatement method is to reduce noise levels (at relevant windspeeds/wind directions) by a clearly noticeable degree. From a receiver's point of view, a reduction of 2.1 dB is barely perceptible or imperceptible . On the other hand, 5dB is thought to be an easily noticeable noise differential, which is why it is commonly used to limit the emergence of WTN over background noise levels. Therefore, all other things being equal (and strictly subject to the point made at para. 214 below), a 5 dB reduction in the WTN at relevant windspeeds/wind directions is likely to abate the nuisance to an appreciable extent at the windspeeds/wind directions concerned.


212. Second, I am convinced that to simply order a 5 dB reduction in the WTN would be fraught with difficultly. Such an approach would first require the assessment of background noise levels in order to isolate the WTN and discern its level at each relevant windspeeds/wind direction. This would involve extended noise monitoring. It would then be necessary to devise and trial a bespoke turbine mode to achieve the required noise level reduction at each relevant windspeed/wind direction. This is turn would require further extended monitoring to verify the noise reduction. As a matter of certainty, this would lead to further dispute and to ongoing nuisance whilst the matter is regularised. This would be entirely unjust to the plaintiffs who have long awaited a fair resolution to their complaints.


213. An order requiring a 5 dB reduction in WTN (at relevant windspeeds/wind directions) would not therefore be sufficiently clear or enforceable and would require ongoing court supervision. Instead of ordering a 5 dB reduction in WTN, I prefer to approach nuisance abatement during quiet waking hours by restricting T2 to an appropriate Enercon operating mode, provided that this is predicted by Enercon to achieve a 5dB reduction in WTN noise level at relevant windspeeds. I am of the view that, with some margin of error, this is a reasonable and fair approach to mitigation during quiet waking hours. At night time however, I accept that, for the reasons outlined by Mr. Stigwood, [35] the predicted WTN reductions are unlikely to be reliably and consistently achieved. Accordingly, I am not  be satisfied that restricting T2 by operation mode only would be effective at night. Therefore, save at very high windspeeds (i.e. at 12 m/s and above), restricting T2 by operation mode only would not be a reasonable or fair approach to mitigation during night hours.


214. Third, Ms. Webster gave evidence at module 1 that what often disturbs her sleep is a sudden change in the WTN, rather than the absolute loudness or quality of the WTN at a given time.  Sudden changes in windfarm noise occur as a result of high AM values, changes in the spectral content of the WTN and as a result of its erraticism, impulsivity and unpredictability. Sudden changes in the WTN would also of course occur if the turbines were to be continually switched on and off as windspeeds rise and fall. I am therefore satisfied on the balance of probabilities, that continually switching on and off the turbine with each increase or decrease in windspeed would in itself be jarring, disturb sleep and cause nuisance at night. Therefore, this should be avoided in crafting the abatement order. On the other hand, even if such jarring effect is likely to be somewhat annoying and distracting during quiet waking hours, I find that it can reasonably be tolerated and would not in itself amount to nuisance.


215. I have determined that nuisance is established but also that the public interest requires that the operation of T2 should be restricted no more than is necessary. On the basis of the findings of fact made at para. 186, I must now determine what precise operation modes ought to be directed per windspeed/wind direction in order to abate the nuisance at sensitive times and then tailor an injunction accordingly.

 

Windspeeds of  5 m/s to 7m/s inclusive


216. For reasons already set out, I find that the WTN is most intrusive at windspeeds of 5 m/s to 8 m/s inclusive. In line with the starting point identified at para. 211 above, and subject once again to the concern expressed at paras. 212 - 214 above, I have in the first instance considered a 5 dB noise reduction at windspeeds of 5 m/s to 8 m/s can be achieved by directing a change in the operating mode of T2.  If so, this could potentially provide an effective mitigation strategy during quiet waking hours.


217. However, a 5dB reduction in noise levels at windspeeds of 5 m/s to and 7 m/s is not predicted to occur on any of operating modes presented by the defendant to the court. Even the lowest power mode, the 1,000 mode is only predicted to affect a maximum noise level reduction of 4.1 dB (at windspeeds of 7m/s only). As I am satisfied (a) that windspeeds 5 m/s to 8m/s are those of greatest adverse impact and (b) that a clearly noticeable detection in noise levels cannot be secured by adopting one of the operating modes presented, shutdown of T2 at night at windspeed of 5m/s to 7 m/s is required.


218. As regards, wind direction, some reduction in overall noise levels probably occurs in wind directions other than directly downwind. However, Mr. Carr has not addressed this in any detail in his evidence in module 2. Therefore, even if I were satisfied that some variation were appropriate in other wind directions,  I am in the dark as to what that might be. This is regrettable; but it is the inexorable result of the manner in which the defendant has chosen to litigate module 2.  On the other hand, I am satisfied that T2 does not cause WTN nuisance at any windspeed during quiet waking hours in the 135 to 180 wind direction or at night in the 90 to 180 wind direction. I am satisfied, on the balance of probabilities, that it is not necessary to order turbine shut down (or indeed other abatement measures) at any windspeed during quiet waking hours in the 135 to 180 wind direction or at night in the 90 to 180 wind direction.


219. Accordingly, I order shut down of T2 at windspeeds of 5m/s to 7 m/s during quiet waking hours for all wind directions save in the 135 to 180 wind direction. No restriction is necessary during quiet waking hours in the 135 to 180 wind direction. At night time, I order shut down of T2 at windspeeds of 5m/s to 7 m/s for all wind directions save in the 90 to 180 wind direction. This same wind direction limitation applies seriatim below.  

Windspeeds of  8 m/s


220. At 8m/s, the 1,000 mode predicts an average reduction in WTN of almost 6 dB. Although this precise reduction may not be consistently achieved, I am nonetheless of the view that this measure will sufficiently abate the nuisance during quiet waking hours. I will therefore restrict T2 to the 1,000 mode during quiet waking hours at a windspeed of 8 m/s.


221. However, the position is different at night. Due to stable meteorological conditions, I am not satisfied that this deduction can be reliably or consistently achieved at night across all of the relevant wind directions between 180 and 90. As sleep disturbance is, and has always been the primary complaint , it is essential that any night time abatement measure is clear, certain in its effectiveness and enforceable.  If not, a requirement for further court supervision would be inevitable.  I am also satisfied that the sudden commencement and cessation of WTN as the wind increases and drops above and below 8m/s would have a jarring effect liable to disturb sleep. I therefore find that, due to a combination of high AM values, thump AM and this jarring effect, permitting the commencement of operation of T2 as the wind reaches 8m/s would cause a continuing nuisance at night. Accordingly, I order that T2 remain shut down at night at a windspeed of 8m/s.

 

Windspeeds of  9 m/s


222. AM values drop somewhat at 9 m/s. However, I have found that, due to a combination of relatively high AM values and thump AM, both of which are likely to occur with increasing frequency (in the sense of rapidity at this high windspeed) the WTN poses a nuisance at this windspeed.  


223. I order that during quiet waking hours the turbine shall operate in the 1,200 mode at windspeeds of 9m/s. This is predicted to bring about an average 3.6 dB noise level reduction. Although this reduction is somewhat less than 5dB, I am satisfied that when balanced with the higher background masking noise levels which winds of 9m/s will provide this will sufficiently abate the nuisance during quiet waking hours.  I will therefore restrict T2 to the 1,200 mode during quiet waking hours.


224. At night, the points made at para. 221 above apply with equal force. Although the masking background noise level from the wind will be higher at 9m/s, the defendant has provided no detail in this regard. No evidence has been put before me upon which I could be satisfied either that the predicted noise level reduction can be consistently and reliably achieved in stable atmospheric conditions at night or that that background wind noise would mask the jarring effect of the sudden and unpredictable commencement and cessation of operation as the wind rises to and falls below 9m/s. Accordingly, I order that T2 remain shut down at night at a windspeed of 9m/s.

 

Windspeeds of 10 m/s and 11 m/s


225. Table 3 shows that AM values at windspeeds of 10 m/s and 11m/s are on average the same as at 9m/s. Whilst, it is common case masking wind noise will increase at these higher windspeeds, I have no specific data as to the extent of this increase. In stable atmospheric conditions, high AM values and thump AM are liable to disturb sleep at night and thus cause a nuisance.


226. I have carefully considered whether to permit the turbine to operate at night at these windspeeds in a reduced power mode. However, I am once again constrained by a lack of evidence as to the reliability of the predicted noise level reductions at night. I am also constrained by a lack of evidence as to the efficacy of background wind noise in masking either the WTN or the jarring effect of a sudden and unpredictable commencement and cessation of operation of T2. Without such evidence, I cannot be satisfied that operation in a lower power mode will abate the nuisance. If I were to craft a mitigation order without such evidence, it would in reality be little better than a guess. I will therefore continue to order the shut down of T2 at night at windspeeds of 10 m/s and 11 m/s.


227. By contrast, stable atmospheric conditions are unusual in the day time. In any event, the primary concern at higher windspeeds was of sleep disturbance. As such, I am satisfied that it is not necessary to restrict the operation of T2 at windspeeds of 10m/s and 11 m/s during quite waking periods.

 

Windspeeds of  12 m/s and above


228. At night time I will order that T2 operate in the 1,200 KW mode at windspeeds of 12 m/s and above. This is predicated to reduce WTN by between 3 and 4 dB. Even if this noise reduction is not consistently achieved over all relevant wind directions, I am satisfied that wind noise will mask turbine noise to a large extent and that this measure will abate the nuisance. I impose no restriction on the operation of T2 at windspeeds of 12 m/s and above during quiet waking hours.

 

Conclusion

229. I close by once more regretting the defendant's failure to engage constructively with the mitigation process. It trialled only one entirely ineffectual mitigation mode and instead devoted itself to disproving nuisance. The defendant therefore failed to adduce important evidence such as properly presented AM values, WTN levels in different wind directions, background noise levels/masking noise levels or verification of the WTN level reductions in the Enercon prediction data. Had it done so, then it would probably have been open to me to devise more nuanced abatement measures inuring to the benefit of the defendant and the public.  Instead, having caused a nuisance for seven years, the defendant has squandered its opportunity to partake in any meaningful way in the design of fair, proportionate and effective abatement measures. Any difficulties that the defendant may encounter on foot of this court's order are entirely self-inflicted



[1] In brief, AM refers to periodic variation in WTN levels.

 

[2] See para. 576 et seq. of the principal judgment.

[3] The meaning of each of these concepts discussed is explained in the principal judgment. In brief, AM refers to periodic variation in WTN noise levels. AM values are a measurement of the peak to trough differential in such noise levels. When, as here, the WTN is of lower frequency, AM will manifest as a "thump" rather than a "swish".

[4] Such as windspeed, wind direction, meteorological conditions and time of day.

[5] It appears that both parties intended to call a combination of expert valuers, architects, estate agents and quantity surveyors to deal with the accommodation claim.

[6] Although, of course, damages for past WTN nuisance would need to be assessed regardless.

[7] Total operational noise comprises the WTN and the background noise

[8] This methodology is explained at para 194 et seq. of the principal judgement

[9] The plaintiffs dispute that the Phase 2 Report has been properly applied. See paras. 102-112 below.

[10] One can see the equivalent spiderweb graphs in respect of the 2024 1,600 mode data at para. 161 below.

[11] One can see the equivalent table in respect of the 2024 1,600 mode data at p. 32 below.

[12] Cited with approval by the Court of Appeal in Gaultier v. The Registrar of Companies [2025] IECA 58.

[13] Albeit that I did not accept that it conveys the impact of AM for the listener, which Mr. Carr now concedes.

[14] In my principal judgment, I fully accepted that the IOA RM was a robust assessment method but not that it was the exclusive AM assessment method for the purposes of WTN nuisance.

[15] Although not advanced as such in submissions, this also effectively amounts to a further argument that the disputed new evidence was not "in existence at the time of the trial".

[16] This apparently profound innovation was not referred to, even in passing, in Mr. Carr's report.

  [17] Mr. Stigwood's witness statement states that there are some "important variations" as between the IEC and the IOA RM. However, the point being made is that the IEC directs the measurement and reporting of an extensive range of data that was not presented in Mr. Carr's IEC AM analysis. Mr. Stigwood did not accept that there are significant variations as between the two methodologies in the sense argued by counsel for the defendant.

[18] A low noise environment is one where background noise levels are less than 30dBA

[19] Thus, the only change in the WTN brought about by altering its operation from the 2,300 mode to the 1,600 mode is to reduce WTN by a maximum of 2.1 dB at windspeeds of 9 m/s and above.

[20] As interpreted by the defendant, WEDG 2006 does not limit WTN by reference to background sound levels save in low noise environments where the limit is 35-40 dB. See para. 188 of the principal judgment where I accept this interpretation of WEDG 2006.

[21] Referring in passing to this court's principal judgment.

[22] This methodology was developed by the Department for Environment, Food and Rural Affairs for the assessment of statutory WTN nuisance complaints. The criteria outlined are similar to the criteria applied to such complaints by the Environmental Protection Agency.

[23] These are set out at para. 385 of the principal judgment.

[24] See paras. 190, 192, 221, 276, 365 and 512 - 518 of the principal judgment.

[25] Cited with approval by the Court of Appeal in Gaultier.

[26] Which it is agreed is to be read together with a letter from the plaintiffs' solicitors on 17th June 2024.

[27] In oral evidence, Mr. Stigwood clarified that the outdoor/indoor noise level differential though an open window would be in the order of 10-12 decibels. For a window open only for ventilation, one would expect a slightly lower differential. This was in accordance with the evidence of both parties at the earlier module that, with a window very slightly open for ventilation purposes, one could assume a 10 dB reduction externally to internally.

 

[28] Mr. Carr restricts this to between the hours of 23.00 and 04.00 to avoid the dawn chorus. However, I prefer to adopt the most conservative approach and to use the spiderweb graph for the entire period of 23.00-07.00 hours.

[29] Mr. Carr restricts this to between the hours of 23.00 and 04.00 am to avoid the dawn chorus.

[30] Downwind would usually be considered within 45 degrees either side of the Ballyduff windfarm turbines.

[31] As to which see para. 218 below.

[32] Between 23.00-07.00 hours on all days.

[33] Between 18.00-23.00 hours all day plus 07.00-18.00 on Sundays and 13.00-18.00 on Saturdays.

 

[34] Part of the he disputed new evidence includes a Table summarising AM penalties in the 2,300 mode. This suggests that AM values are somewhat lower at these high windspeeds in the 2,300 mode than in the 1,600 mode. Neither expert has commented upon this. I will adopt the more conservative approach and assume that AM values are generally as set out in table 3.  

[35] See para. 149 above.

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