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GLA Waste Heat Strategy

London, UK

º£½ÇÊÓƵ supported the Greater London Authority (GLA) to build a clear overview and understanding of the waste heat opportunities around the capital.

London’s transition to low carbon heat will not be achieved by a single technology. It needs a city‑scale view of supply and demand, a clear picture of where low carbon heat already exists, and practical routes to move that heat to where it is needed most. Working with the GLA through the Local Energy Accelerator, our team assessed London’s largest recoverable waste heat sources and how they could catalyse multi‑borough heat networks.

The Waste Heat Study sits alongside our River Thames Study. Together they illustrate how recovered heat from energy from waste facilities, wastewater treatment works, data centres and other sources, complemented by water source heat pumps on the Thames, could underpin an interconnected heat network for London. The combined studies identify more than 10,000 GWh per year of rejected heat from London’s top waste heat sources. Seven strategic areas emerge from the modelling, together covering 25 boroughs and showing how to serve at least 3,700 GWh per year of demand over time (with opportunities for further expansion).

Over a 40‑year period, the indicative carbon saving is in the order of 40 million tonnes of CO₂ equivalent. These potential pathways could support heat network zoning and local area energy planning, and prioritise waste heat where it is available so that limited river capacity (a further 1,530 GWh/year) can serve dense central districts that lack viable alternatives.

The project mapped London’s largest waste heat sources, identifying over 10,000 GWh/year of recoverable heat potential across 25 boroughs.

We developed seven strategic heat network areas, showing how multi-borough networks could cut 40 million tonnes of COâ‚‚ over 40 years.

Our experts created a robust modelling approach, validated against existing feasibility studies to ensure realistic, actionable outputs.

The team catalysed next steps, supporting the Greater London Authority (GLA) and boroughs to form partnerships and draft outline business cases for delivery.

Challenge

Ambition at the scale of a city the size of London brings complexity. The starting point is data, and while London has rich datasets, they carry uncertainty. Publicly available figures for waste heat and building demand draw on multiple sources, compiled using different methods and at different times. That means headline potentials must be treated as indicative until site‑specific validation confirms temperatures, duty cycles and export capacity.

The team approached this transparently, setting out assumptions, applying gap analyses to avoid double counting, and testing sensitivity where ranges were wide. Even then, some sources, particularly data centres and industrial sites, require early engagement to verify the true exportable heat and the space available for recovery equipment.

Governance is just as important as engineering. Multi‑borough networks cross administrative boundaries and transport corridors, and they intersect with existing and proposed local networks. Aligning delivery models, ownership, tariff structures and phasing requires coordinated leadership between boroughs, the GLA and delivery partners. We explored this in engagement with North London boroughs and our Heat Zoning Delivery Model Assessment work with GLA and London Councils under the Local Energy Accelerator programme.

Solution

First, we mapped and classified waste heat across London by grade. High‑grade sources, such as energy from waste plants, can supply networks without temperature uplift. Low‑grade sources, such as wastewater treatment works and data centres, can be upgraded using heat pumps. These sources are now integrated into the for all to access.

We combined these sources with demand information for buildings from the London Heat Map and development pipelines from the London Datastore, then clustered adjacent loads using a buffered linear heat density method. This identified anchor clusters that merit connection, while the Steiner tree algorithm traced shortest routes along the highways network. We focused on routes that maintained the target linear heat density of 8 MWh per metre or more, then integrated existing and proposed heat networks to avoid duplication and to illustrate how interconnection can grow over time.

The result of the modelling is a set of seven sub-regional areas: North London Waste Authority (NLWA) in the north, Beddington, Royal Docks, Mogden and Twickenham, Hayes and West Drayton, Crossness and South Bermondsey, and OPDC (Old Oak and Park Royal Development Corporation). Taken together they illustrate approximately 487km of primary pipework and around £2.3 billion of indicative capital expenditure for trunk infrastructure and energy centres.

Each area sets out a pragmatic next‑step pathway, from forming cross‑borough working groups to preparing outline business cases and delivery models. In North London we went further, building an initial techno‑economic cash flow model using a Department for Energy Security and Net Zero (DESNZ) template to test routing options and phasing. That work demonstrates a potentially economically viable network with grant support assumptions, and a 98% reduction in operational carbon against a gas boiler counterfactual as the grid decarbonises.

Technical analysis is only half the story. The study process convened the market. At a GLA session at City Hall – the Clean Heat for London event held in June 2025 – more than 120 stakeholders took part, including potential heat providers, network investors and London borough representatives. That conversation immediately improved the evidence base. For example, Cory Riverside indicated materially greater exportable heat capacity than had been assumed at desktop stage, highlighting why engagement can push the opportunity beyond the modelled baseline. In parallel, we advised on how to prioritise waste heat first, then deploy River Thames capacity where periphery sources cannot reach, particularly in boroughs with acute space constraints for plant.

The methodology also embeds social value. By overlaying clusters with areas of high social housing density and NHS estate locations, the routes show how heat networks can help decarbonise public services and reduce fuel poverty risk where heat is most needed. This provides a powerful basis for coordinated investment, and for sequencing phases that deliver early benefits while building the backbone for later expansion and interconnection.

Value

The immediate value to the GLA is a clear picture of London’s waste heat potential and steps to unlock it. The study strengthens the London Heat Map with new waste heat layers, validates alignment with the national zoning model, and provides boroughs with indicative network footprints that can be refined through local area energy planning and future zoning work. For investors and operators it highlights scale. Multi‑borough networks can access diverse, resilient heat portfolios and serve clusters that drive strong linear heat density, which is fundamental to commercial viability.

Crucially, the work has already moved beyond the page. Following the strategic study, the GLA has begun engaging boroughs in each opportunity area to develop workable partnerships. In North London we supported the formation of a cross‑borough approach, including a draft strategic outline case and a memorandum of understanding that sets the terms for collaboration. Elsewhere, pipeline concepts are advancing. Cory Riverside and partners are exploring long‑reach transmission that could extend towards Westminster and the City, illustrating the kind of ambition that a strategic lens unlocks. As data centre policy evolves, our separate project with the GLA also supports siting decisions that weigh electrical, cooling, water and heat offtake considerations together.

For Londoners, the value is long term and tangible. Multi-borough heat networks powered by recovered heat cut carbon sharply, track grid decarbonisation, and reduce dependence on volatile fossil fuel supply. By prioritising waste heat where it is plentiful and reserving finite river capacity for central areas that lack alternatives, the approach maximises the whole‑city benefit. The vision is an integrated set of sub‑regional networks that can interconnect over time, balancing loads, sharing sources and delivering affordable low carbon heat at scale.