NHS Foundation Trust. 170-year-old site. EPC Band C asset rating. DEC Band F operational performance — deteriorating. A gas CHP system approaching the moment it becomes a carbon liability. And a commitment to net zero by 2040 that the data does not yet support.
The Building
How this was produced
This analysis draws entirely on UK public data registers. No site visits were conducted, no proprietary data was purchased, and no assumptions were made that cannot be traced back to a named source. The methodology — NBIP's Reality Simulation Engine — works by collecting data from 25 authoritative sources and reading them together. Most of the findings below are invisible in any individual source. They only become visible when the sources are cross-referenced.
Pillar 1 — Aggregated Truth
EPC, DEC, Annual Reports, NHS ODS, VOA, Planning — the verified factual baseline across 12 sources.
Pillar 2 — Reality Check
Satellite ground motion (EGMS), LiDAR, flood risk, air quality, geology, climate — what this building faces in the real world.
Pillar 3 — Future Inference
CHP transition risk, Green Plan trajectory, expansion carbon accounting, planning context — where the asset is heading.
25 Sources — All Collected
5-Year Energy Record
CO₂e from utilities (tCO₂e) — Trust-wide (Chelsea + Sutton + Cavendish Sq + Kingston MDU). Source: Royal Marsden Annual Reports 2023/24 and 2024/25.
* 2023/24 CHP failure year: Sutton CHP plant offline, grid electricity imports +60%, gas −32%. Used as Green Plan baseline — an artificially low year. 2024/25 shows the normalised operational position. NHS Net Zero Building Standard target: <100 kgCO₂e/m². Current position: 119.9 kgCO₂e/m² and rising.
Findings
Each finding is the product of cross-referencing multiple sources. Where a finding carries an action, it is addressed to the institutions with responsibility for the building — not to NBIP.
Confidence Tier 4 — High
25 sources collected across all three pillars. Energy data verified directly from Royal Marsden Annual Reports and NHS ERIC. EGMS ground motion confirmed from 303 Sentinel-1 InSAR data points (March 2020 – April 2025, RMSE ±0.43mm). LiDAR coverage from EA National LiDAR Programme (TQ27NE, 1m resolution, 2015). EPC and DEC verified from MHCLG open data API. VOA, OS UPRN, and NHS ODS all confirmed from primary registers. Planning data from RBKC and GLA portals. Three sources partial: LiDAR tile boundary 429m south of site, Chelsea-vs-Sutton energy split not published separately, ERIC Trust-specific download not accessed.
Realistic Carbon Cut Methods
Based entirely on what the data shows about this building. Ordered by carbon impact, and grounded in what the Trust has, what it is planning, and what the energy record actually supports.
Transition the Sutton CHP to a heat pump by 2030
The Sutton CHP is 13 years old and will need a major overhaul or replacement within 3–5 years. At that decision point, like-for-like gas renewal locks in Scope 1 emissions through the 2040 net zero target date. Replacing a 1,000 kW gas system with an 80°C heat pump cuts approximately 550–1,300 tCO₂e per year (confirmed NHS hospital case studies). The Oak Cancer Centre at Sutton already uses electricity for heating and hot water — the precedent is established on this estate. Salix financing and PSDS funding are available. Capital cost estimate: £1.5–3m.
Do not renew the Chelsea CHP beyond 2032 — plan the transition now
The Chelsea 1.5 MW CHP (installed ~2021/22) has a 10–12 year engine life. Its first major decision point is approximately 2031–2033 — exactly when the grid carbon tip-point arrives. Once UK grid carbon intensity falls below ~100 gCO₂/kWh (expected ~2030), gas CHP at 180 gCO₂/kWh actively worsens the Trust's carbon position. The PP/26/00240 plant room layout is still being finalised: this is the correct moment to specify heat pump infrastructure for the combined Chelsea estate, not after occupation.
Maximise solar PV on the new extension roof from day one
The G+6 extension (PP/26/00240) must achieve BREEAM Excellent — which mandates on-site renewable generation. The new roof (estimated 1,200–1,800 m² usable) could support 250–400 kWp of PV, generating 225,000–440,000 kWh/year and saving 40–75 tCO₂e/year. The 2026/27 planned additional PV at Chelsea (Green Plan confirmed) is the first tranche; the extension roof is the second. Required by BREEAM regardless — zero additional capital risk.
Rebaseline the Green Plan before publishing 2025/26 data
The 2023/24 baseline of 9,654 tCO₂e was a CHP-failure year — approximately 10% below the normalised operating position. A 3-year average (2021/22 + 2022/23 + 2024/25 = 10,053 tCO₂e) produces a rebaselined 2032 target of approximately 2,011 tCO₂e — honest, demanding, and defensible to any insurer, lender, or sustainability auditor reviewing the public record. Publishing year-two performance against a mechanically distorted baseline is a credibility risk.
Accelerate heat recovery on high air-change clinical zones
The Green Plan confirms 40 ventilation systems upgraded to direct-drive. MVHR on clinical areas running high air change rates — radiotherapy suites, theatres, sterile environments — can cut heating demand by 60–80% on those zones. Lower capital than heat pumps. Requires infection control validation. The upgrade programme should prioritise the highest-energy clinical areas first.
Establish ground motion monitoring before PP/26/00240 excavation begins
At −1.17 mm/yr baseline subsidence on a Victorian structure, basement excavation in London Clay creates a material differential settlement risk. Structural remediation is energy-intensive and carbon-costly. A pre-construction InSAR monitoring network (quarterly readings during construction) identifies acceleration before it becomes structural damage. Low cost relative to the risk — recommended as a planning condition of any PP/26/00240 consent.
Conclusion
The Royal Marsden is committed to net zero by 2040 and has published a Green Plan to get there. The public data does not yet support the trajectory. The DEC is Band F and deteriorating. CO\u2082e rose 11% in the first year of the plan period. The two CHP plants that have anchored the Trust's energy economics for a decade will become carbon liabilities before the target date. A 15,659 m\u00b2 expansion \u2014 necessary, clinically justified \u2014 will widen the carbon gap unless the new building is designed from the outset to be the decarbonisation vehicle, not an additional load.
None of this is visible from the EPC. None of it is visible from the DEC alone. None of it is visible from the Annual Report, the Green Plan, or the planning application read in isolation. It becomes visible when all of them are read together \u2014 cross-referenced against satellite ground motion, air quality, geological risk, and the structural logic of the UK's energy transition. That is what this analysis does. That is what NBIP is for.
This is what public data looks like when you read all of it at once.
The EPC, the DEC, the Annual Report, the Green Plan, the planning application, the satellite ground motion data, the air quality readings — they all exist. They are all public. None of them, read alone, tells you what is actually happening to this building. Read together, the picture is clear.