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Has the environment been properly assessed?

Large data centres usually need an Environmental Impact Assessment before planning permission can be granted. You do not need to be a lawyer to check whether it has been done properly. This page explains what to look for, what to ask, and what to do if information is kept from you.

The short version

  • An Environmental Impact Assessment (EIA) is meant to tell the council, and you, what a development will do to the environment before it is decided.
  • Check three documents on the planning file: the screening opinion, the scoping opinion and the environmental statement.
  • Watch for important topics “scoped out”, old or second-hand assessments, and serious questions left to be “dealt with by condition”.
  • If documents are missing, you have a legal right to environmental information. Ask through WhatDoTheyKnow.

What an EIA is

In Wales the rules are in the Environmental Impact Assessment (Wales) Regulations 2017; England has its own, very similar, regulations.[1][2] They say that for certain kinds of development, planning permission must not be granted until the likely significant effects on the environment have been identified, described and assessed, both direct and indirect, on people and their health, wildlife, land, soil, water, air, climate, landscape and heritage, and the way these affect one another.[3]

The Supreme Court has said the purpose is to ensure that decisions are made “with full knowledge and public awareness of the likely significant environmental consequences”.[4] It is not a vote for or against a scheme. It is about making sure nobody decides in the dark.

The regulations at a glance (Wales)

  • Regulation 2 defines the terms used. When in doubt about a word, check it there first.
  • Regulation 3 is the most important: planning permission must not be granted for EIA development unless an EIA has been carried out.
  • Regulation 4 and Schedule 4 set out what the assessment and the environmental statement must cover. These are the main tests of whether a statement is good enough.
  • Regulations 5 and 6, with Schedules 2 and 3, deal with screening: which projects may need an EIA, and the criteria for deciding.

The Welsh Government publishes its own guidance.[20] The rules in England are similar but not identical, so check which apply.

The four stages, and what to check at each

  1. Screening: does it need an EIA at all?

    The council (or the Welsh Government) gives a screening opinion. A large data centre will usually count as an “urban development project” once it covers more than one hectare, and an on-site power plant over half a hectare is listed separately.[5] Screening and scoping opinions must be placed on the public planning register.[6]

    A request for a screening opinion must come with a plan, a description of the development, and a description of its likely significant effects, including its emissions and its use of water, land and other natural resources.[21] A letter that simply argues that no EIA is needed does not supply that information.

    Check: Is the screening opinion on the file? Does it describe the scheme now proposed, or an earlier, different one? Was the request that led to it complete? If the answer was “no EIA needed”, are the reasons convincing?

  2. Scoping: what will the assessment cover?

    The developer can ask the council for a scoping opinion, which sets out the topics the environmental statement must cover. Topics can be “scoped out” if they are thought unlikely to matter.

    Check: Which topics were scoped out? For a data centre, energy, waste heat, water, noise from back-up generators and climate are rarely unimportant. Was the scoping opinion given for this scheme? In one current Welsh application, the developer’s planning statement says formal scoping “has not been repeated” for a 150 MW data centre, relying on an opinion given in 2022 for ordinary commercial units.[7]

  3. The environmental statement: what does it actually say?

    The environmental statement (ES) is the developer’s report. By law it must include, among other things, the energy the development will use and the natural resources it will consume; an estimate of its emissions “such as water, air, oil and subsoil pollution, noise, vibration, light, heat, radiation”; the reasonable alternatives considered; effects combined with other existing or approved projects; and a non-technical summary written for the public.[8]

    Check: Start with the non-technical summary. Then look for real numbers: peak water use, electricity demand, generator running hours, heat produced. Words such as “to be confirmed at detailed design” or “subject to the eventual operator” are worth questioning.

  4. The decision: did the council reach its own conclusion?

    Before granting permission, the decision-maker must reach a reasoned conclusion on the significant effects, which must be up to date, and must consider whether monitoring should be required.[9]

    Check: Does the officer’s report to committee set out that conclusion clearly, or simply repeat the developer’s summary?

“We will deal with that by condition”

Councils often attach conditions to a permission: for example, that a drainage scheme or a noise plan be approved later. That is normal. What the courts have said is that conditions cannot take the place of the assessment itself.

  • In Gillespie, the Court of Appeal held that where measures to deal with a problem are “not plainly established and not plainly uncontroversial”, the case “calls for an EIA”, and criticised a decision that used a condition “effectively as a surrogate for the EIA process”.[10]
  • In Champion, the Supreme Court accepted that mitigation can sometimes be taken into account, but said that “cases of material doubt should generally be resolved in favour of EIA”, and that where the measures had not been fully identified the case was “an archetypal case for EIA”.[11]
  • In Finch, the Supreme Court held that the assessment must include effects that occur away from the site, if they are effects of the project.[4]

Put simply: if a significant effect is uncertain enough that it has to be worked out later, it should have been assessed first, so that the public could see it and comment on it before the decision. That is our summary of the cases, not legal advice; each case turns on its own facts, and the courts do not always quash a decision even where the process was flawed.[11]

Ask: the planning officer handling the application

“Which of the likely significant environmental effects of this development are proposed to be dealt with by conditions or at reserved-matters stage rather than assessed in the environmental statement; why can they not be assessed now; and will the Council’s reasoned conclusion address them before the application is decided?”

Follow-up: If the reply is unclear, request the officer’s working papers and any correspondence with the developer on the scope of the assessment through WhatDoTheyKnow.

Linking the assessment to the issues on this site

Each of the concerns on this site corresponds to something the environmental statement should address. Use the table to check the file, and follow the links for the questions to ask.

ConcernWhere it belongs in the EIAWhat to look for in the statement
WaterWater; population and human health; natural resources usedNormal and maximum daily water use; what happens in a drought; sewerage capacity; where waste water goes.
Power and the gridEnergy demand; climate; indirect effectsElectricity demand; emissions from generating that electricity; on-site generators and how long they will run; any temporary power plant.
Waste heatEmissions, including heat; alternativesHow much heat will be released, and whether using it for heating or glasshouses was considered.
Chemicals, noise and decommissioningAir, water and soil; human health; major accidents; wasteFuel and chemical storage, including any PFAS in cooling or fire suppression; generator noise and air quality; what happens when the site closes.
Who is affectedPopulation; cumulative effectsWhether people sharing the same reservoir, sewage works or grid were considered, not only near neighbours.
Resilience and clusteringCumulative effects with other projects; major accidentsOther data centres planned nearby, assessed together rather than one at a time.
How decisions are madeAlternatives; the decision itselfWhether other sites and designs were genuinely compared, and whether the council reached its own conclusion.

Some concerns on this site, such as who controls the data or the wider risks of AI, are not environmental effects and usually fall outside an EIA. They can still be raised as planning or policy questions.

If information is not released: your rights

The Aarhus Convention, an international treaty to which the United Kingdom is a party, gives the public three linked rights in environmental matters: to get information, to take part in decisions, and to go to court when those rights are not respected.[12]

The right to information is given effect by the Environmental Information Regulations 2004. Information about a development’s effects on water, air, land, noise or energy is environmental information. A public authority must provide it within 20 working days,[13] must “apply a presumption in favour of disclosure”, and cannot refuse information on emissions on certain commercial or confidentiality grounds.[14] If you are refused, you can ask the authority to reconsider within 40 working days[15] and then complain to the Information Commissioner.[16]

The simplest way to ask is WhatDoTheyKnow. It is free, it sends your request to the right address, and the request and the reply are published, so others can see what has been asked and what has been withheld.[17] Water companies such as Dŵr Cymru also answer environmental information requests.

Example request, via WhatDoTheyKnow, to the council

“Under the Environmental Information Regulations 2004, please provide: (1) the screening opinion and any scoping opinion for application [reference], with the request and supporting information on which each was based; (2) any correspondence with the applicant about whether a new screening or scoping opinion was needed; and (3) the responses of Natural Resources Wales and the water company to the environmental statement.”

Follow-up: If refused, ask for reconsideration within 40 working days, then complain to the Information Commissioner.

If you think the rules have not been followed

  • Write before the decision. Set out the gap plainly to the planning officer and to councillors on the planning committee, and ask for it to be addressed in the officer’s report.
  • Ask the Welsh Government. You can ask Welsh Ministers to consider making a screening direction, or to call in the application to decide it themselves.
  • Take advice quickly if you are thinking of going to court. A challenge to a planning decision must usually be brought within six weeks.[18] In environmental cases covered by the Aarhus Convention, the costs you could be ordered to pay the other side are normally capped at £5,000 for an individual and £10,000 for a group.[19] Planning Aid Wales and environmental law charities can help you find advice.

This page is general information, not legal advice. See the disclaimer.

EIA checklist and example requests (Word)

Sources

  1. The Town and Country Planning (Environmental Impact Assessment) (Wales) Regulations 2017 (SI 2017/567 (W. 136)). https://www.legislation.gov.uk/wsi/2017/567/contents/made
  2. The Town and Country Planning (Environmental Impact Assessment) Regulations 2017 (SI 2017/571), which apply in England. https://www.legislation.gov.uk/uksi/2017/571/contents/made
  3. EIA (Wales) Regulations 2017, regulation 4 (what the assessment must cover). https://www.legislation.gov.uk/wsi/2017/567/regulation/4/made
  4. Supreme Court, R (Finch on behalf of the Weald Action Group) v Surrey County Council [2024] UKSC 20, press summary (judgment 20 June 2024). https://supremecourt.uk/cases/press-summary/uksc-2022-0064
  5. EIA (Wales) Regulations 2017, Schedule 2 (projects that may need EIA, with thresholds). https://www.legislation.gov.uk/wsi/2017/567/schedule/2/made
  6. EIA (Wales) Regulations 2017, regulation 27 (screening and scoping opinions to be placed on the planning register). https://www.legislation.gov.uk/wsi/2017/567/regulation/27/made
  7. Cardiff Council planning register, application 26/00109/HYB (Planning Statement, January 2026, paragraph 2.12; Environmental Statement Volume II, Appendix 1.2, scoping opinion SC/21/00018/MJR). https://www.cardiffidoxcloud.wales/publicaccess/applicationDetails.do?keyVal=T8YL3PECJ8T00&activeTab=documents
  8. EIA (Wales) Regulations 2017, Schedule 4 (what an environmental statement must contain). https://www.legislation.gov.uk/wsi/2017/567/schedule/4/made
  9. EIA (Wales) Regulations 2017, regulation 25 (reasoned conclusion, kept up to date, and monitoring). https://www.legislation.gov.uk/wsi/2017/567/regulation/25/made
  10. Court of Appeal, Gillespie v First Secretary of State [2003] EWCA Civ 400, paragraphs 37-48. https://caselaw.nationalarchives.gov.uk/ewca/civ/2003/400
  11. Supreme Court, R (Champion) v North Norfolk District Council [2015] UKSC 52, paragraphs 45-62. https://caselaw.nationalarchives.gov.uk/uksc/2015/52
  12. UNECE, 'Introduction to the Aarhus Convention'. https://unece.org/environment-policy/public-participation/aarhus-convention/introduction
  13. Environmental Information Regulations 2004, regulation 5 (duty to make environmental information available within 20 working days). https://www.legislation.gov.uk/uksi/2004/3391/regulation/5
  14. Environmental Information Regulations 2004, regulation 12 (presumption in favour of disclosure; information on emissions). https://www.legislation.gov.uk/uksi/2004/3391/regulation/12
  15. Environmental Information Regulations 2004, regulation 11 (asking the authority to reconsider, within 40 working days). https://www.legislation.gov.uk/uksi/2004/3391/regulation/11
  16. Information Commissioner's Office, 'How to access information from a public authority'. https://ico.org.uk/for-the-public/official-information/
  17. WhatDoTheyKnow, free service for making and publishing information requests. https://www.whatdotheyknow.com/
  18. Civil Procedure Rules, Part 54, rule 54.5(5) (six-week time limit for judicial review of planning decisions). https://www.justice.gov.uk/courts/procedure-rules/civil/rules/part54
  19. Civil Procedure Rules, Part 46, rule 46.26 (costs limits in Aarhus Convention claims). https://www.justice.gov.uk/courts/procedure-rules/civil/rules/part-46-costs-special-cases
  20. Welsh Government, 'Environmental impact assessment (EIA) guidance' (December 2025). https://www.gov.wales/environmental-impact-assessment-eia-guidance
  21. EIA (Wales) Regulations 2017, regulation 6 (what a request for a screening opinion must contain). https://www.legislation.gov.uk/wsi/2017/567/regulation/6/made