Coolglass Windfarm Supreme Court Climate Obligations
Coolglass Windfarm Limited v. An Coimisiún Pleanála
Supreme Court Decision
On 4 February 2026, the Supreme Court issued its judgment in Coolglass Wind Farm Limited v An Coimisiún Pleanála [2026] IESC 5. The decision represents a significant development in Irish environmental, planning and administrative law, having direct relevance to how public bodies must approach their statutory functions in light of Ireland’s climate legislation.
Background
The case concerned an application by Coolglass Windfarm Limited (Coolglass) for planning permission to build a 13-turbine wind farm in Co. Laois. An Bord Pleanála (as it then was) refused the application on the basis of visual concerns which would cause the building of wind farms in the relevant area to contravene the local Laois County Development Plan.
Coolglass challenged the refusal on several grounds, including that An Bord Pleanála had failed to properly discharge its obligations under Ireland’s climate legislation under Section 15(1) of the Climate Action and Low Carbon Development Act 2015 (Section 15(1)) (as amended by the Climate Action and Low Carbon Development (Amendment) Act 2021 (the 2021 Act)).
In January 2025, Justice Humphreys of the High Court delivered judgment in favour of Coolglass and made an order of certiorari, quashing the decision by An Bord Pleanála to refuse to grant planning permission for the wind farm. Justice Humphreys interpreted the duty imposed by Section 15(1) (as amended) as, in practice, requiring planning authorities to “almost always” grant planning permission for renewable energy projects.
Following delivery of the High Court judgment, An Bord Pleanála sought leave to appeal the decision. On 4 February 2026, the Supreme Court delivered a detailed and considered 94-page judgment, rejecting the appeal and upholding the decision of Justice Humphreys, albeit on different and narrower grounds.
Section 15(1) of the Climate Action and Low Carbon Development Act 2015 (as amended)
Section 15(1) places an obligation on public bodies to exercise their functions in favour of climate concerns when making decisions, unless it is objectively impracticable to do so.
The section (as amended) provides that [emphasis added]:
A relevant body shall, in so far as practicable, perform its functions in a manner consistent with:
- the most recent approved climate action plan,
- the most recent approved national long term climate action strategy,
- the most recent approved national adaptation framework and approved sectoral adaptation plans,
- the furtherance of the national climate objective, and
- the objective of mitigating greenhouse gas emissions and adapting to the effects of climate change in the State.
The Relevant Test
While the Supreme Court upheld the facts of Justice Humphreys decision, it found a different interpretation of Section 15(1).
The original text of Section 15(1) merely required relevant bodies to “have regard to” climate objectives. Section 15(1) was amended by the 2021 Act (as highlighted above), strengthening the obligation of relevant bodies and requiring performance of all their functions be consistent with climate objectives so far as is practicable. That obligation is, in principle, enforceable by a court.
The Supreme Court broke the test into two core components.
Firstly, the requirement to act in a manner consistent with climate obligations places a positive obligation on relevant bodies to align their decision making with Ireland’s climate targets. The Court described an obligation to perform a function consistent with certain matters as:
“more than a process obligation. It does not simply dictate what steps must be taken before a function is performed. It is addressed to the outcome, which must be capable of being demonstrated to be consistent with an identified standard”.
Further, the Court noted that this implies there is a “range of possible outcomes” open to relevant bodies that may satisfy the section and “a degree of tolerance in the manner in which this is to be achieved”.
In distinguishing itself from the interpretation of Justice Humphreys, the Court (in the context of planning decisions) determined that the “question of consistency … with the s. 15(1) objectives, is much more complex than a traffic light system of climate friendly (go) (unless impracticable) and climate unfriendly (stop).”
Secondly, the phrase in so far as practicable further qualifies the obligation. The Court noted that the inclusion of this wording meant that it is expected that there may be circumstances where it is not possible to make decisions consistent with climate objectives, where it is not practicable to do so. The concept of practicability comprehends what is practical in the circumstances and appropriate to the requirements of the situation.
Summarising the correct application of the test imposed by Section 15(1), the Supreme Court stated that the section:
“operates as a form of climate sense check, and to ensure that decisions and actions of public sector bodies are all aligned with the climate objectives. The section 15(1) obligation is not more prescriptive than that: first because the objective with which consistency is required, is stated at a level of significant generality; second, because consistency implies a range of possible outcomes; and finally, because even that degree of consistency is not required, if it is impracticable”.
Implications for Public Bodies
The Supreme Court construction of Section 15(1) is a welcome development which will help guide relevant bodies in their decision making. While the Coolglass case concerned the decision of a planning authority, all public bodies must be aware of the obligations placed on them by Section 15(1).
The Court acknowledged that the impact of Section 15(1) will vary depending on the functions of the relevant body, and the matters they are obliged to have regard to, or to implement and also that the section does not expand the existing functions of relevant bodies or create new functions, rather it is the existing functions of relevant bodies that must be performed in a manner consistent with its objectives. It observed that, in the context of individual planning decisions, the section does apply at a granular level, because that is a function of a relevant body, but noted the impact of the section may be less decisive in the field of planning, where considerations of climate change mitigation are already woven into the planning code, than in the case of other relevant bodies.
It is now important for public bodies to familiarise themselves with Ireland’s climate targets, and to understand how their decisions may contribute to or interfere with these targets. The standard requires a good faith effort to identify how the decision can be made in a manner consistent with climate obligations, and to pursue that consistency unless there are genuine reasons as to why it is not practicable.
Section 15(1) does not mandate that climate objectives are deemed more important than other legitimate considerations that public bodies deal with in their decision making. The judgment of the Supreme Court makes it clear that it will not always be possible for climate objectives to be at the forefront of decisions. Indeed, both the High Court and Supreme Court judgments recognised, in the context of the specific planning decision before them, that emission creating developments may be properly permitted. Financial, economic and social factors play a fundamental role in public body decisions, and these factors will sometimes be more important than climate concerns in a given context. Where this is the case, we would suggest that documenting the reasoning for departing from climate considerations in favour of a competing objective is now of paramount importance.
However, relevant bodies should not seek to hide behind the qualification contained in Section 15(1). Where decisions can be made which align with climate considerations, this should be done, unless impracticable to do so. Simply stating that it was not practicable to do so, without legitimate reasoning for it, leaves bodies open to their decisions being scrutinised and even quashed as part of lengthy and expensive court processes.
Practical Guidance
The key takeaway for public bodies regarding this decision is simple: climate obligations cannot be ignored. When faced with a decision or acting within its powers:
- public bodies should make genuine assessments of how the proposed decision aligns with or departs from climate objectives;
- the consideration of climate objectives should be documented and evidenced in a decision-making record;
- where a public body reaches the conclusion that consistency with climate obligations is not practicable, it should have clear reasons for this decision.
Conclusion
The Coolglass decision underscores that Ireland’s climate legislation imposes enforceable obligations on public bodies. The requirement to act consistently with climate objectives ‘insofar as practicable’ is a legal duty which must be discharged in good faith.
Public bodies should ensure that their decision-making processes reflect this duty, and that decisions which depart from climate objectives are supported by legitimate reasons. Failure to do so may expose their decisions to successful legal challenge.
Please contact us if you required assistance and/or guidance in understanding the implications of the Coolglass decision for you. Our experienced team is well positioned to provide comprehensive support.
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