The House of Commons Environmental Audit Committee opened its inquiry into the environmental impact of UK data centres on 27 February 2026, with a report expected later this year. The inquiry lands at a moment when the sector’s electricity demand trajectory is, in the Secretary of State’s own words, “inherently uncertain” and the policy instinct to constrain what cannot be measured is strong. For operators, this is not a spectator event. It is the forum in which the narrative about UK data centre growth will be set. The terms of reference make clear that the Committee wants to hear a constructive answer.
Those terms of reference explicitly ask what role renewables can play in cutting the sector’s carbon footprint, what emerging technologies can minimise environmental impact, and what opportunities data centres offer to power and heat local communities. Each question has a deliverable answer in 2026. The operators that will shape the Committee’s conclusions are those that can point to what they are already doing.
The most resilient operators are building that answer now, and it takes the form of a sustainability stack: a layered set of measures across both sides of the meter, combining cleaner energy inputs with genuinely useful outputs such as waste heat, grid services and demand flexibility. Each layer is independently valuable. Taken together, they amount to a proposition that changes how a data centre project reads to planners, regulators, host communities and anchor tenants.
Cleaner inputs
Corporate power purchase agreements, past the headline
The distinction between physical and virtual PPAs is well understood by this market. Physical PPAs deliver electrons through a licensed supplier; virtual or synthetic PPAs settle financially against a wholesale reference price and pair the offtaker with the renewable attributes rather than the molecules. Both structures are now mature in the UK data centre context. The more pressing questions for 2026 lie beyond the choice of PPA structure.
The question of whether the PPA brings new generation onto the grid or merely re‐labels existing supply is attracting materially closer scrutiny. Both the Climate Change Committee and the Environmental Audit Committee can be expected to interrogate the practice of purchasing unbundled renewable energy certificates, effectively rebadging existing clean power as additional capacity. Hyperscaler colocation contracts are moving in the same direction, with increasingly prescriptive sustainability flow‐downs that require tenants to demonstrate that their procurement adds megawatts. Operators whose PPA portfolios cannot withstand that test face a growing reputational and commercial exposure.
Tenor matching is the next pressure point. Data centre offtake horizons of 15 to 20 years sit awkwardly against generator appetite, which in the current market rarely extends beyond 10 to 12 years for a fixed‐price commitment. The practical answer is to layer the exposure: a firm initial tenor of 10 years with contractual options such as blend‐and‐extend mechanics or pre‐agreed re‐pricing windows that give both sides a structured route into the back years. Pairing two or three PPAs of staggered vintage, so that re‐contracting risk does not concentrate in a single year, is a further refinement that the more sophisticated offtakers are already adopting.
Separately, any PPA being negotiated this year needs to price in the basis risk introduced by potential zonal pricing reform. Consider a data centre in the South East of England contracting with a Scottish onshore wind farm under a virtual PPA referenced to a single national wholesale price. Under a locational pricing model, that offtaker would be exposed to a persistent spread between a lower Scottish generation zone price and a higher South East demand zone price. If the spread averages £15–20/MWh, a plausible illustrative range on the basis of existing constraint cost patterns, the economics of the PPA change fundamentally. The settlement mechanics need to specify which locational reference applies and allocate the basis differential between the parties. They also need to address the possibility that the reform timetable slips or that the final DESNZ model diverges from current proposals. Contracts that are silent on this risk are storing up a dispute. Operators that can demonstrate genuine additionality, with structures robust enough to survive these market reforms, will read better to regulators and anchor tenants.
Behind‐the‐meter and on‐site generation
Where land permitting allows, on‐site solar paired with battery storage is moving from a marginal contribution to a material one, particularly at sub‐hyperscale sites. Private wire arrangements need to be structured within the supply licence exemption regime under the Electricity (Class Exemptions from the Requirement for a Licence) Order 2001, subject to the applicable thresholds and conditions. Those conditions impose constraints on resale and third‐party supply that are not always appreciated until they bite. For sites where co‐located generation exceeds the applicable threshold for onshore generating stations, the nationally significant infrastructure project regime under the Planning Act 2008 may be engaged, adding a consenting layer that needs to be anticipated at feasibility stage. The contractual interface between on‐site generation, resilience commitments and any Capacity Market participation deserves attention from the outset.
For larger sites, direct connection to a dedicated renewable asset, sometimes via a sleeved PPA or a private wire to a co‐located project, offers a route around the connections queue that has become one of the defining frustrations of UK data centre delivery. The commercial structure must be right and the grid connection agreement must accommodate the arrangement.
Small modular reactors: a 2030s option to structure for now
Nuclear sits at the long end of the input stack. In April 2026, Great British Energy – Nuclear signed a contract with Rolls‐Royce SMR, formally commencing design and procurement work on the UK’s first three small modular reactors at Wylfa on Anglesey. First power is anticipated in the mid‐2030s, subject to regulatory approvals and a final investment decision.
The data centre angle is more direct than is often appreciated. The Autumn 2025 Budget confirmed two AI Growth Zones in Wales with Rolls‐Royce SMR involvement, an explicit governmental pairing of nuclear capacity with digital infrastructure demand. SMR PPAs are not a 2026 procurement option, but for operators planning long‐horizon campuses the structuring work starts now. That means monitoring the Generic Design Assessment timeline, engaging with GBE – Nuclear’s emerging commercial framework for offtake, and understanding the siting and land assembly constraints that will determine which projects reach final investment decision. It also means ensuring that option agreements or heads of terms drafted today are flexible enough to accommodate a technology and regulatory pathway that will evolve materially before first power. The contractual templates being developed now will shape the deals that close at the end of the decade.
Useful outputs
Heat reuse and the new zoning regime
The single most underappreciated UK development in this space is the heat network zoning regime under Part 8 of the Energy Act 2023. Government published its consultation response in January 2026, with implementing regulations expected to be laid in Parliament in spring 2026. The regime is not voluntary. Within a designated zone, certain buildings can be required to connect to a heat network as consumers, and, crucially for data centre operators, large heat sources can be required to connect as suppliers. Government’s own response document names “surplus heat from data centres” among the sources the regime is built to capture. The obligation structure operates in two tiers: planning safeguards take effect at zone designation (Tier 1), with active connection obligations following the competitive appointment of a zone developer (Tier 2). Operators with sites in or near prospective zones need to understand now whether they will be classified as obligated heat sources, because the design and cost implications of that classification are substantial.
Read with the right lens, this regime solves a chronic UK problem. Heat offtake from data centres has been commercially marginal in this country because demand certainty was missing. The experience in Stockholm, Helsinki and Copenhagen, where dense district heating networks make export viable, and the Tallaght district heating scheme in South Dublin, where Amazon’s heat offtake has demonstrated what is possible at scale, show what demand certainty unlocks. Heat network zoning supplies that missing piece by underwriting demand.
The legal workstreams that follow are well understood in outline: heat supply agreements with terms long enough to align with infrastructure lifespans; design integration so that liquid cooling and heat recovery are engineered in at site selection; and planning strategies that anticipate how zone designations will interact with development consents. An operator that builds a facility without heat recovery capability in a location subsequently designated as a heat zone faces either a costly retrofit or a regulatory confrontation. Operators that engage with the Advanced Zoning Programme and the forthcoming designation pipeline early will shape how the regime applies to their assets.
Grid services and demand flexibility
The second output story sits inside the data hall itself. The UPS and battery infrastructure on a typical data centre site, installed for resilience, is in principle capable of participating in NESO’s balancing services markets, including the Dynamic Containment, Dynamic Moderation and Dynamic Regulation suite of frequency response products. From 9 April 2026, NESO’s Demand Flexibility Service expanded to include bi‐directional flexibility, introduced zonal procurement and lowered the eligibility threshold to 0.1 MW, all of which materially improves accessibility for data centre participation.
The honest position, however, is that the gap between theoretical capability and practical deployment remains wide. UPS batteries are specified, warranted and maintained for resilience, not for regular cycling. Repurposing them for frequency response risks accelerated degradation, potential warranty invalidation and a reduction in the autonomy window that underpins every customer SLA on the site. Most OEM warranty terms were not drafted with ancillary service dispatch in mind. Renegotiating them adds cost and complexity that can exceed the revenue opportunity, which, set against colocation rents, is modest. Aggregator arrangements must sit comfortably with N+1 or 2N resilience commitments, and any participation must respect Capacity Market rules and the technical performance requirements of each service. For most operators today, the more realistic route is dedicated behind‐the‐meter battery storage, sized and warranted separately from the resilience plant. The strategic value lies in the regulatory positioning. A data centre that actively supports grid stability strengthens its standing with policymakers, planning authorities and host communities.
Pulling it together
The value of treating these measures as an integrated stack comes from the way the design choices interact. Liquid cooling shapes heat export economics. On‐site generation shapes flexibility revenues. PPA structure shapes how a project reads to its anchor tenant’s sustainability team and to the Environmental Audit Committee. The decisions that lock in or lock out these options are taken early: at site selection, grid application, planning submission and tenant negotiation. The operators that have this stack in motion will be the ones demonstrating what the sector’s growth delivers.
Bird & Bird’s International Data Centre Group works with operators, developers and investors on the energy, projects and regulatory workstreams that sit behind each layer of the sustainability stack. For more information on any of the issues raised in this article, please contact Jenny Murray.
For further information, please contact:
Giuliana Polacco, Partner, Bird & Bird
jenny.murray@twobirds.com
