Data Centres, Climate Obligations, And Mathematical Argument Limitations

In Doyle & Ors v An Coimisiún Pleanála (No. 3), the High Court (Court) dismissed a judicial review challenge to planning permission for a hyper-scale data centre near Ennis, Co. Clare.

The applicants (two environmental NGOs and three individuals) challenged An Coimisiún Pleanála's (Commission) decision to permit six two-storey data centre buildings on a 60-hectare site, with a 120MW gas-powered energy centre and associated substation infrastructure.

This was the third instalment in the Doyle litigation. Module I addressed a bat roost issue and was dismissed. The second judgment in Module I dealt with costs.

Module II, heard in March 2026, tackled the climate grounds. What makes this judgment significant is the Court's detailed application of the Supreme Court's framework in Coolglass v An Coimisiún Pleanála [2026] IESC 5 to an emissions-causing development for the first time at the High Court level. The applicants lost on every ground.

The Coolglass Framework in Practice

Section 15 of the Climate Action and Low Carbon Development Act 2015 (as amended) requires relevant bodies, including An Coimisiún Pleanála, to perform their functions in a manner consistent with, amongst other things, the relevant Climate Action Plan, the national climate objective, and the objective of mitigating greenhouse gas emissions. The Supreme Court in Coolglass clarified that this creates a legal standard enforceable by courts, not a mere procedural checklist.

Humphreys J in Doyle distilled the practical implications. The test is whether the decision falls within the spectrum of possible outcomes that could be said to be consistent, insofar as is practicable, with section 15. It is not a traffic light system. A planning authority is entitled to start with a presumption that compliance with the development plan will itself satisfy the section 15 duty. Where the development plan has been adopted consistently with climate objectives and the site is identified for a particular use, that presumption carries real weight.

This anchors the section 15 analysis in the existing planning framework. Consistency is assessed as a spectrum, conditioned by practicability, viewed through the lens of what was before the decision-maker at the time.

Sectoral Ceilings, Carbon Budgets, and the ETS

The applicants contended that the Commission was required to establish the remaining emissions headroom within the relevant sectoral ceiling, calculate the project's emissions, reconcile the two, and refuse permission if the threshold was exceeded. The Court rejected this.

The Commission and the developer argued that carbon budgets and sectoral emissions ceilings are tools of national governance, not statutory caps directed at individual planning authorities or projects.

The Court noted a basic problem with the applicants' contention in this regard – carbon budgets and sectoral emissions ceilings are not expressly referred to in section 15(1). In addition, the Commission had, in fact, referred to carbon budgets and sectoral emissions ceilings. Judge Humphreys found that the flexibility within section 15 means that a decision-taker is not mandatorily obliged to quantify the amount of emissions from a development in every case. Ultimately, the Court found the applicants' argument unsustainable because they did not show that the Commission's decision fell outside the lawful range of available options, per Coolglass. Also, the applicants' argument failed to account for the mitigation of effects resulting from the Corporate Power Purchasing Agreements (CPPAs) proposed by the developer.

The Court also addressed the EU Emissions Trading System (ETS). The development's electricity-related emissions fall within the ETS, and the Commission was entitled to consider that regulatory architecture when assessing magnitude and significance. However, the Court acknowledged that ETS participation alone does not automatically demonstrate full consistency with domestic climate obligations – the Commission had other matters in its favour, including the developer's agreement to enter into CPPAs.

Mitigation

On CPPAs, the Court took a practical approach. Although the formal conditions did not contain an explicit CPPA requirement, conditions 1 and 3, which required the development to be carried out in accordance with the submitted documentation, collectively had that effect. The Court added a recital to the order to remove any doubt.

The 2015 Act does not require refusal of developments with gross emissions; the range of options available to a decision-maker includes having regard to net emissions after mitigation, conditions, and offsets.

However, Judge Humphreys sounded a note of caution, stating that it is "not immediately obvious as a general principle why projects creating net GHGs should be allowed to use the sky as an open sewer for free". This sentence highlights the need for developers to give the carbon impact of a proposed development detailed treatment in its application documents, taking into account risks of carbon leakage, sufficiently identifying the baseline scenario as regards carbon-generating projects which the project may replace, risks of rebound effects and induced demand, etc.

Bat Roosts and Derogation Licences

The applicants argued that a derogation licence should have been obtained before consent was granted, relying on the CJEU's decision in Namur-Est (Case C-463/20). The Court rejected this argument.

On the facts, the Court found that a single Leisler's bat observed in March 2022 was almost certainly not going to remain at the same location. The applicants had not shown that the need for a derogation licence was probable rather than merely possible.

Practical Takeaways

Our key takeaways from the Court's decision are as follows:

1. The Court's judgment confirms that section 15 of the Climate Action and Low Carbon Development Act 2015 (as amended) does not preclude the Commission from granting planning permission for a development that generates substantial GHG emissions.
2. Compliance with section 15 is not a simple mathematical exercise. The question is whether the planning authority's decision falls within a range of outcomes that are consistent with climate objectives, assessed through the lens of practicability and the material before the authority. This highlights the need for developers to give climate impacts detailed treatment in planning application documents, taking into account the relevant climate plans, policies and objectives referred to in section 15.
3. The developer's commitment to CPPAs was a relevant mitigation factor. Even though the planning conditions did not contain a standalone condition requiring CPPAs, the Court found that they effectively incorporated CPPA obligations.

This is the most detailed judicial treatment to date of how section 15 operates in the context of a major development that causes emissions. It is essential reading for anyone involved in any emissions generating development or climate-related planning challenge in Ireland.

Contributed by Emma Louise Nolan

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