Supreme Court Clarifies Climate Obligations in Planning Decisions

A recent Supreme Court decision has clarified how climate obligations must be applied in planning decisions. The Court confirmed that planning authorities have a legal obligation to ensure that any decision to grant or refuse planning permission is consistent with the climate objectives set out under section 15(1) of the Climate Action and Low Carbon Development Act 2015. Our Planning & Environment team explores the implications of this decision for stakeholders.

What you need to know

• An Coimisiún Pleanála’s appeal of the High Court decision in this case was dismissed.
• The Supreme Court found that the High Court came to the right conclusion but was incorrect in its reasoning.
• A detailed examination of the interpretation of section 15(1) of the Climate Action and Low Carbon Development Act was carried out by the Court.
• Planning authorities have a legal obligation to consider climate objectives.

The Supreme Court gave judgment in Coolglass Wind Farm Limited v An Bord Pleanála[1] on 4 February 2026. It has clarified how climate obligations must be taken into account by planning authorities when making planning decisions. The judgment arose from a challenge to a decision of An Coimisiún Pleanála (the Commission) to refuse planning permission for a wind farm in County Laois. Coolglass Wind Farm Limited (the Developer) was refused planning permission. The refusal was based on the fact that granting permission would contravene the Laois County Development Plan. The Development Plan did not permit wind farms in the area.

The Developer challenged the refusal in the High Court. In doing so, it relied on the climate obligations contained under section 15(1) of the Climate Action and Low Carbon Development Act 2015 as amended by the Climate Action and Low Carbon Development (Amendment) Act 2021 (the Act). The High Court quashed the Commission’s decision. As later described by the Supreme Court, the High Court prescribed a form of ‘decision tree’. This demonstrated a strong disposition in favour of the grant of permission for renewable energy projects. The Commission appealed the High Court decision to the Supreme Court.

The Supreme Court dismissed the appeal, but on significantly narrower grounds than those relied on by the High Court. In doing so, the Court provided important guidance on the interpretation and application of section 15(1) of the Act.

The interpretation of Section 15(1) of the Act

Section15(1) of the Act provides that:

"A relevant body shall, in so far as practicable, perform its functions in a manner consistent with—

(a) the most recent approved climate action plan,

(b) the most recent approved national long term climate action strategy,

(c) the most recent approved national adaptation framework and approved sectoral adaptation plans,

(d) the furtherance of the national climate objective, and

(e) the objective of mitigating greenhouse gas emissions and adapting to the effects of climate change in the State. [emphasis added]"

The Supreme Court examined each element of the provision. It also considered how the provision applies when a "relevant body" exercises a statutory function. This includes deciding whether to grant or refuse planning permission. While the Court agreed with the High Court’s conclusion, it held that the High Court’s reasoning was flawed in key aspects.

"Relevant body"

Section 6 of the Act adopts the definition of a “public body” from the Freedom of Information Act 2014. The Supreme Court described this definition as “very wide indeed”, noting that the Act applies “across the public sector generally”.

The Court confirmed that the Commission and local authorities are “relevant bodies” for the purposes of section 15(1) of the Act.

The Court acknowledged that the impact of section 15 on various public bodies will vary depending on the functions of that body. It will also depend on the matters those bodies are obliged to consider or implement.

"Functions"

Section 15(1) of the Act imposes what the Court described as an “obligation of consistency” which applies to the functions of a relevant body. Importantly, the provision does not expand or create new statutory functions. Relevant bodies may only act within the functions granted to them by statute.

Section 15(1) does not create new functions for relevant bodies. Instead, it requires existing statutory functions to be exercised in a way that is consistent with the climate objectives set out in the Act. As a result, the effect of section 15(1) is confined to the limits of those existing functions.

The Court explained that in the context of planning applications:

• It is a function of the Commission to grant or refuse planning permission, and
• That function does not replace or override the obligations of the Commission under section 15(1).

The Court indicated that section 15(1) of the Act is a “statutory reset”. It explained that the provision reminds all relevant bodies that, when performing their functions, they must do so in a manner consistent with climate objectives, "in so far as practicable".

"Consistent with"

The Court analysed the level of obligation the term “consistent with” placed on relevant bodies carrying out their functions.

The Supreme Court disagreed with the High Court’s interpretation of this phrase. The High Court had treated the obligation as a strict “comply with” obligation. The Supreme Court found this approach was incorrect, noting that an obligation to act consistently is not the same as an obligation to achieve compliance.

The language of “consistent with” was seen by the Supreme Court to:

• Be instructive, and
• Provide a range of outcomes to the relevant body, these outcomes being consistent with the objectives of section 15(1) of the Act.

The existence of more than one outcome is crucial; this creates a lesser obligation than indicated in the High Court. The Supreme Court’s interpretation allows for what they describe as a “degree of tolerance” in the way in which the obligation is met. This means that relevant bodies do not have to comply with the climate objectives under section 15(1) of the Act. Instead, relevant bodies must make their decisions in a manner consistent with climate objectives. That decision will vary widely on a case-by-case basis.

"In so far as practicable”

The Court indicated that the phrase “in so far as practicable” qualifies the entire obligation under section 15(1) of the Act. The Court emphasised that departure from climate objectives is permissible only where there are genuine practical difficulties that make full alignment impracticable. A departure cannot be justified by convenience alone.

The Court contrasted this phrase with:

• “insofar as possible”, a more demanding standard, and
• “reasonable”, a less demanding standard.

It placed “in so far as practicable” somewhere between the two standards.

The Court described this process as a “form of climate sense check” to make sure functions are aligned with climate objectives where possible.

The Court’s interpretation of section 15(1) of the Act creates a legal test. Under this test, any decision of a relevant body must fall within the “spectrum” of outcomes that can be regarded as “consistent” with section 15(1) of the Act. This applies in so far as practicable.

Application to individual planning decisions

The Court indicated that, in individual planning decisions, section 15(1) of the Act will not often be determinative. This position is based on the presumption that climate objectives are already embedded in the planning framework. Planning authorities are generally entitled to proceed on the basis that any strategy or development plan is consistent with those climate objectives.

Where a planning application is made to the Commission and section 15(1) of the Act is relied on in an application, then the Commission should be able to explain why its decision to refuse/grant the permission is consistent “as far as practicable” with climate objectives. The Court described this as a “relatively simple exercise”, but one which must nonetheless be carried out.

Application in Coolglass

Applying its interpretation of section 15(1) of the Act to the facts, the Supreme Court held that:

• The interpretations of section 15(1) of the Act advanced by both the Developer and the Commission were incorrect.
• Although the Developer placed limited emphasis on section 15(1) of the Act in its application, the fact that it was relied on at all required substantive engagement by the Commission.
• The central issue was whether the Commission should grant permission despite the fact that the Development Plan would be contravened, given it has the discretion to do so.
• The Commission’s failure to engage meaningfully with section 15(1) of the Act, coupled with its reliance on the Development Plan contravention as a reason for refusal, meant that the decision was not consistent with its statutory obligation.

The failure to engage with section 15(1) of the Act was “an error of law” on the part of the Commission and was “fatal to the validity of the decision”.

The Court remitted the planning decision to the Commission for reconsideration. It directed the Commission to assess whether it should carry out its function to grant the permission in light of its obligations under section 15(1) of the Act, even if doing so would contravene the Development Plan.

Conclusion

This decision confirms that section 15(1) of the Act is more than a purely procedural requirement. Relevant bodies must meaningfully engage with climate considerations when exercising their statutory functions. They must also ensure that their decisions fall within the spectrum of outcomes that can be viewed as consistent, insofar as practicable, with national climate objectives.

At the same time, the Supreme Court made clear that section 15(1) of the Act does not mandate climate-led decision-making to the exclusion of all other considerations. Climate objectives must be considered and addressed, but they do not automatically override development plans or other statutory requirements.

The judgment will have significant implications for planning authorities, An Coimisiún Pleanála, and numerous statutory bodies across the public sector. Climate considerations are no longer an afterthought: where relied on, they must be substantively and transparently considered and addressed.

For guidance on the implications of this decision, please reach out to a member of our Planning & Environment team.

People also ask

[1] Coolglass Wind Farm Limited v An Bord Pleanála[1] [2026] IESC 5

The content of this article is provided for information purposes only and does not constitute legal or other advice.