A focus on air quality: Data centre feasibility studies and site selection

This sixth article in our Data Centre Thought Leadership Series outlines the challenges to consider in data centre site selection and feasibility studies, with a specific spotlight on air quality considerations. It serves as a follow-on article from ‘Data centre site selection and feasibility studies’ which can be accessed below, along with the other articles in this series.

Whilst data centres seek to both decarbonise and secure alternative power supplies, onsite back-up power in the form of combustion-driven generators is still likely to be the default choice in the immediate future, until a reliable non-combustion alternative is established. As such, air quality impacts will remain a potential constraint requiring consideration in any data centre feasibility study.

Air quality has moved up the agenda in public consciousness over the last decade and as such feeds into ‘not in my back yard’ (NIMBY) objections to planning applications. Whilst data centres may have been used to a relatively easy ride through the planning process, they are increasingly encountering opposition. Both a 96MW development in Abbot’s Langley, Hertfordshire and a 140MW campus at the Court Lane Industrial Estate, Buckinghamshire were rejected in the last few years by planning authorities and went to appeal. [1] Recently in the press, Digital Reef have faced opposition from residents and environmental campaigners at their Havering site.[2] This further emphasises the importance of robust feasibility assessments to mitigate against an environmental impact coming to the fore in the latter part of the project cycle and derailing a project.

Any feasibility assessment should consider the routine testing of the generators as well as unlikely grid outage scenarios. Whether the generators run on diesel or more sustainable hydro-treated vegetable oil (HVO), they still result in combustion emissions, with the most impactful being nitrogen oxides. Nitrogen oxides are subject to air quality standards for both human health as well as ecosystems and it is the latter that could well present feasibility issues. As data centres seek power supply and space availability, they are increasingly likely to be pushed to green belt and the new ‘grey belt’,[1] and this means greater likelihood of being in proximity to internationally or nationally protected ecological sites.

An air quality feasibility checklist should include presence of Air Quality Management Areas, proximity of other data centres (to consider cumulative effects of a cluster), sensitive human exposure locations, and protected ecological sites. Early assessment can help identify any potential constraining factors and what mitigation (HVO, selective catalytic reduction, or an alternative non-combustion form of back-up power) may need to be considered in the design process. The environmental regulators’ approach to data centres is now starting to crystalise with some formalised publications, however the majority of the fine detail remains in informal guidance notes and in permitting decision documents. For this reason, the feasibility assessment should draw upon experienced consultants and not just rely on a ‘check list’ approach.

In summary, the consideration of air quality impact forms a key part of any data centre site feasibility study, due to its potential constraints on a project. This is down to the complex mix of growing nimby-ism, the potential for data centre sites to be pushed on to the green/grey belt, and evolving regulatory guidelines. Conducting an in-depth feasibility study including air quality impact is therefore integral to decision making for data centre site selection.

How SLR can help

At SLR we’ve been working with data centre clients for more than 15 years on planning and permitting applications. We’ve supported industry associations and are frequently in discussion with the Environment Agency on technical matters of assessment.

If you need support with your project, we have the experience to provide it. Get in touch with our specialists.

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References

1. https://www.datacenterdynamics.com/en/news/london-data-center-campus-havering-hydrogen-fuel-cell/

2. https://www.datacenterdynamics.com/en/analysis/london-data-center-market-2025-uk-angela-rayner/