Carbon Accounting for Healthcare and the NHS in the UK

The NHS is the world's first health service to commit to a net-zero target. With a combined carbon footprint of approximately 25 million tonnes CO2e per year, it is also the UK public sector's single largest emitter. For NHS trusts, private hospital groups, and healthcare suppliers, carbon accounting has moved from a policy aspiration to an operational requirement.

This guide covers the key emission sources for UK healthcare organisations, SECR obligations, the NHS net-zero framework, and where the most material reduction opportunities lie.

UK Healthcare Emissions Overview

Hospitals are among the most energy-intensive building types in existence. A district general hospital typically operates 24 hours a day, 365 days a year, with clinical spaces requiring stringent temperature and air quality controls. Medical gases, surgical equipment, imaging systems, and sterilisation processes all consume significant energy and generate direct emissions.

Where the Emissions Come From

Scope 1 - Direct emissions for healthcare include natural gas for heating and steam generation, medical gases (particularly nitrous oxide, which has a global warming potential 298 times that of CO2), anaesthetic gases such as desflurane (a potent greenhouse gas), and on-site fleet vehicles.

Anaesthetic gases alone account for roughly 5% of the NHS's total carbon footprint. Desflurane is 2,500 times more potent than CO2 and was widely used in UK operating theatres until NHS England accelerated its phase-out. Switching to lower-impact alternatives such as sevoflurane and propofol-based total intravenous anaesthesia (TIVA) delivers immediate carbon reductions without compromising patient outcomes.

Scope 2 - Purchased electricity is a major source for healthcare organisations, driven by continuous operation of diagnostic equipment, lighting, HVAC systems, and IT infrastructure. At a typical acute trust consuming 40–60 GWh of electricity per year, even the current UK grid factor of 0.207 kg CO2e/kWh represents thousands of tonnes of CO2e annually. Renewable energy procurement via Power Purchase Agreements (PPAs) or renewable tariffs is now standard practice at larger NHS trusts.

Scope 3 - Supply chain accounts for approximately 60% of the NHS's total footprint and is where the most significant reduction opportunities lie. The largest categories are:

• Pharmaceuticals (Category 1) - manufacturing, packaging, and transport of medicines
• Medical devices and equipment (Category 1)
• Food and catering (Category 1)
• Patient and visitor travel (Category 6)
• Staff commuting (Category 7)

SECR Requirements for UK Healthcare Organisations

The Streamlined Energy and Carbon Reporting framework applies to UK-quoted companies and large unquoted companies meeting two of three size thresholds: 250 or more employees, £36 million or more in annual turnover, or £18 million or more on the balance sheet.

Most NHS foundation trusts and large private healthcare groups easily meet these thresholds. They must report:

• Total UK energy consumption in kWh
• Scope 1 and Scope 2 greenhouse gas emissions in tonnes CO2e
• At least one intensity metric (for example, kg CO2e per inpatient bed or per procedure)
• A narrative on energy efficiency actions

Carbon accounting in the UK provides a full breakdown of SECR thresholds and reporting timelines. What is SECR reporting explains the disclosure format in detail.

Private Healthcare Groups

Private hospital operators, diagnostic imaging centres, and dental chains meeting SECR thresholds face the same reporting obligations as NHS trusts. Many are now also subject to sustainability requirements from NHS commissioning contracts, where private providers must align with the Greener NHS supply chain programme.

NHS Net-Zero Targets and the Greener NHS Programme

In 2020, NHS England published Delivering a Net Zero Health Service, setting two targets:

• NHS Carbon Footprint: Net zero by 2040 (Scope 1, 2, and Scope 3 activities the NHS directly controls)
• NHS Carbon Footprint Plus: Net zero by 2045 (including the full supply chain and wider value chain)

The Greener NHS programme requires every NHS organisation to publish a Green Plan - a board-approved strategy with annual milestones. Sustainability leads at NHS trusts are now a standard role, and carbon data is reported quarterly to NHS England.

For private healthcare suppliers and pharmaceutical companies, the Greener NHS Supply Chain programme requires vendors above certain thresholds to disclose Scope 1, 2, and 3 emissions and commit to Science Based Targets initiative (SBTi) aligned targets as a condition of procurement.

Carbon Reduction Opportunities in Healthcare

Anaesthetic Gases

Phasing out desflurane is the highest-impact single intervention available to operating theatres. NHS England's phase-out programme demonstrated that switching to sevoflurane and TIVA can reduce anaesthetic-related emissions by up to 95% with no increase in clinical risk. Implementation requires anaesthetist training, updated procurement protocols, and waste gas capture systems.

Energy Decarbonisation

Heat decarbonisation is a major opportunity. Many NHS estates still rely on ageing gas boilers and steam-based heating infrastructure. NHS Energy, the national energy buying framework, offers trusts access to renewable electricity contracts and low-carbon heat network pilots.

On-site solar generation, battery storage, and heat pump installations are being deployed at NHS sites through the Public Sector Decarbonisation Scheme, which provides capital funding for NHS and public sector bodies.

Pharmaceuticals and Medical Devices

How to calculate Scope 3 emissions explains the methodology for supply chain measurement. For healthcare, the most practical approach is to use spend-based emission factors from DEFRA's dataset applied to procurement spend by category - pharmaceuticals, consumables, capital equipment - to establish a baseline.

Reducing pharmaceutical waste through better prescribing protocols and returns programmes directly reduces both cost and Scope 3 emissions.

Patient Travel

Shifting outpatient consultations to virtual or telephone delivery reduces patient travel emissions. An NHS trust with 200,000 outpatient appointments per year could reduce travel-related emissions by thousands of tonnes CO2e annually by converting a proportion of follow-up appointments to remote delivery.

What emissions must NHS trusts report under SECR?

NHS foundation trusts meeting SECR size thresholds must report Scope 1 and Scope 2 emissions, total energy consumption, and at least one intensity metric in their annual reports. The Greener NHS programme additionally requires quarterly carbon data submissions to NHS England and board-approved Green Plans.

How significant are anaesthetic gases in healthcare carbon accounting?

Very significant. Desflurane has a global warming potential of approximately 2,540 times that of CO2. A single operating theatre using desflurane as its primary agent can generate emissions equivalent to several hundred tonnes CO2e per year from anaesthesia alone. Switching to sevoflurane and TIVA is the single highest-impact clinical intervention available.

Does the Greener NHS supply chain programme affect private companies?

Yes. NHS suppliers above certain revenue thresholds must disclose Scope 1, 2, and 3 emissions and commit to SBTi-aligned targets as a condition of NHS procurement contracts. This requirement is being phased in by supplier size, with the largest suppliers already subject to full disclosure requirements.

What intensity metric should healthcare organisations use for SECR?

Common choices include kg CO2e per inpatient bed, per occupied bed day, or per procedure (for surgical centres). NHS England recommends reporting against both a floor area metric and a clinical activity metric to allow comparisons across different types of healthcare facility.

Conclusion

Carbon accounting for UK healthcare organisations is driven by both regulatory obligation and the NHS's world-leading net-zero commitments. For NHS trusts, reducing anaesthetic gas emissions, decarbonising heat, and engaging the pharmaceutical supply chain offer the most material near-term reductions. For private healthcare providers, alignment with the Greener NHS supply chain programme is increasingly a commercial prerequisite. Accurate carbon measurement is the foundation on which all credible reduction commitments rest.