The NHS Net Zero Building Standard: what it means for retrofit and refurbishment of the existing estate

The NHS runs more than 13,500 buildings. Decarbonising that standing estate, while it stays open and keeps treating patients, is the central task, and the NHS Net Zero Building Standard shapes how it is done. The Standard applies not only to new build but to major upgrades of existing facilities, and it sets whole-life carbon limits for major refurbishments and extensions.  

If you plan, refurbish or maintain NHS buildings, this is a guide to what the Standard asks of an existing-estate project, and how to plan retrofit and major works around it. 

This guide explains what the NHS Net Zero Building Standard is, how it treats upgrades to existing facilities, what has changed on funding and progress since 2023, and what estates teams should do next.

First, a point of clarity on dates 

The NHS Net Zero Building Standard was first published by NHS England on 22 February 2023. It was described at the time as the first net zero building standard produced by any national health system. Its publication page was refreshed in August 2026, which has brought it back into view, but the Standard itself remains the February 2023 edition and is current as at September 2026. NHS England has said it will update the Standard periodically as construction methods and technology move on, and a second version has been signalled, so expect the requirements to tighten over time rather than stand still. For now, the February 2023 edition is the one to work to. 

What the Standard is 

At its heart, the Standard is about whole-life carbon. That means two things counted together: 

• Embodied carbon: the emissions locked into a building by its materials and construction, from the steel and concrete to the transport and the site works. 

• Operational carbon: the emissions from running the building once it opens, mainly the energy used for heating, cooling, ventilation and power. 

Traditional design tends to chase operational energy alone. The Standard asks teams to look at both, set limits, and report against them using a defined set of tools. The published package is substantial: the main Standard runs to around 140 pages, and it comes with a User Guide, a compliance matrix, and whole-life carbon, design-management and operational-energy reporting tools. In other words, it is a measurement regime, not a statement of ambition. 

Why this matters for existing buildings 

Two features matter especially if your work is on the estate you already have. First, the Standard applies to major upgrades of existing facilities, not only to new build, and it sets whole-life carbon limits for major refurbishments and extensions. Second, its embodied-carbon hierarchy puts reuse first. Keeping and improving an existing building avoids the large embodied carbon locked into demolition and new construction, so refurbishment is treated as the low-carbon default rather than the poor relation. For a health service with a vast existing estate, that reframes the choice. The lowest-carbon hospital is often the one you already have, improved well. 

Who it applies to 

The Standard applies to investments in new buildings and upgrades to existing facilities where the project cost is £25 million or more, the scheme is subject to the HM Treasury business-case approval process, and it is at or before the pre-strategic outline case (pre-SOC) stage, for schemes from 1 October 2023 onwards. It also applies to New Hospital Programme schemes and to Neighbourhood Health Centre projects. 

For refurbishment specifically, the Standard recognises that hitting new-build energy targets inside an existing building is hard. So it allows more bespoke operational targets, set against the building's existing specification, with any shortfall documented as a formal derogation by the design team. In plain terms, you are expected to go as far as the building sensibly allows, evidence how far that is, and record why anything more was not achievable. That is a realistic, and still demanding, way to treat older estate. 

Here is the part worth holding onto. NHS England has been clear that while the mandatory scope is those larger schemes, the approach to managing whole-life carbon is relevant to all healthcare buildings. So even if your next refurbishment sits below the threshold, the direction of travel is set, and working to the same principles now saves reworking later.

Why it matters, and why now 

The Standard is one of the delivery mechanisms behind the NHS commitment to net zero. The NHS was the first health system in the world to make that commitment, and its targets are enshrined in law: net zero by 2040 for the emissions it controls directly, and by 2045 for its wider footprint including the supply chain, with interim milestones along the way. Buildings are a large share of that, so how the estate is built and run matters a great deal. 

The timing point is simple. Because the Standard bites at pre-SOC stage, the decisions that determine whether a scheme complies are taken very early, often years before completion. If your team is shaping a business case now, the carbon requirements need to be in the room from the first design conversation, not bolted on at the end when the cheap options have gone.

Progress and funding since 2023 

The Standard does not sit on its own. The wider net zero NHS programme has moved on since it was published, and the direction of travel is clear. NHS England's first five-year progress report, published in 2025, put numbers on it: 

• The NHS Carbon Footprint, the emissions the NHS controls directly, has fallen by 14% since the Delivering a Net Zero NHS strategy, and by more than 68% against a 1990 baseline. The NHS says it remains on track for its interim target of an 80% cut by 2032. 

• Estate emissions are down around 10% since 2019/20, helped by a 21% fall in grid-electricity emissions as the national grid decarbonises. 

• The stubborn part is heat. Gas, used mainly for heating, made up about 40% of the NHS Carbon Footprint in 2024/25 and has dropped by only 1% since 2019/20. That is the problem the estate has to crack, and it is largely a retrofit and plant-replacement challenge. 

On funding, several routes have opened up: 

• Since 2020 the NHS has secured more than £1.4 billion in additional capital through the government's Public Sector Decarbonisation Scheme, funding over 100 projects. 

• More than £135 million has gone into energy-efficiency measures such as LED lighting, solar and building management systems. Over half the secondary care estate now has LED lighting, and solar generation has tripled since 2019. 

• In March 2025, Great British Energy and the Department of Health and Social Care announced £100 million to install solar panels and battery storage across NHS trusts. 
• NHS-owned procurement bodies have launched decarbonisation of estates frameworks, reported at around £1 billion, to help trusts move from planning into delivery from late 2026. 

The takeaway for estates teams is that the Standard sets the design bar, and the funding and delivery routes to meet it are increasingly there. The two belong together in your planning. 

A related change: the 2027 procurement rules 

If you procure works and services, there is a connected change worth knowing. From 1 April 2027, NHS England is raising its Carbon Reduction Plan requirements. For contracts worth £5 million or more a year, and for all new NHS frameworks, suppliers will have to report and publish plans covering all of their Scope 1, 2 and 3 emissions across their global operations, aligned to the NHS net zero target. Lower-value contracts keep the existing 2024 standard. In short, the carbon expectations the Standard sets for the building are increasingly matched by carbon expectations on the supply chain that delivers it. 

The tension worth planning for 

One thing to flag early. The Standard is designed to push carbon down, and design commentators have noted that in places it adjusts how existing NHS technical guidance, the Health Technical Memoranda and Health Building Notes, is applied, so that lower-carbon choices are not blocked by older assumptions. That is helpful, but it means design and compliance teams have to read the Standard and its User Guide alongside the HTMs and HBNs, and resolve any apparent conflicts deliberately rather than defaulting to habit. Check the current Standard for the detail; do not assume the old rule of thumb still holds. 

What NHS estates teams should do next 

A practical starting point for an existing-estate programme: 

• Start from your Green Plan and your data. Every trust and integrated care board holds a Green Plan under the Health and Care Act 2022. Line your refurbishment and major-works pipeline up against it, and baseline the energy, carbon and cost of the buildings in scope. 

• Audit before you specify. Building energy audits identify the energy conservation measures worth doing, from fabric and controls to heating plant, so investment goes where it cuts most carbon per pound. 

• Confirm scope for each project. Is the upgrade £25m or more, Treasury-approved, at or before pre-SOC? If so, the Standard applies in full, with the refurbishment derogations noted above. If not, work to the same principles anyway. 

• Sequence heat, fabric and compliance together. Fabric and controls first make heat decarbonisation affordable, and compliance works such as fire, electrical and ventilation can often be planned into the same programme rather than done twice. 

• Plan the electrical capacity. Heat pumps need more electrical capacity, which is one of the biggest practical constraints on hospital retrofit. Design it in early. 

• Phase against the backlog and the funding. Few estates can do everything at once. Use a costed, multi-year programme and match it to funding routes as they open.

7. Watch for version 2. Expect the Standard to tighten, so plan improvements that still look good against a higher bar.

Working with a delivery partner on existing buildings 

Retrofitting an occupied estate is a shared effort. For the trust, it means owning the Green Plan and the condition and energy data, setting the carbon brief, and making the early calls. For the maintenance and refurbishment partner, it means surveying and auditing the buildings, specifying lower-carbon fabric, plant and controls, evidencing embodied and operational carbon, delivering the works safely around a live clinical setting, and keeping the reporting honest into operation. The programmes that go well are the ones where the survey, the scope and the carbon evidence are built together, so nothing unravels at business-case sign-off. 

AXIS CLC works on existing NHS estates. This is the kind of work our group delivers through its decarbonisation, refurbishment, capital works and planned maintenance services, from heat and fabric retrofit to fire safety and wider compliance, turning a carbon standard into completed works in buildings that stay open throughout.

If you are shaping a retrofit or major refurbishment programme for your estate and want to pressure-test the approach, book a call with our team. 

Sources: 

• NHS England, NHS Net Zero Building Standard (document first published 22 February 2023; publication page updated 11 August 2026), https://www.england.nhs.uk/publication/nhs-net-zero-building-standard/ (primary) 

• NHS England, Five years of a greener NHS: progress and forward look (2025), https://www.england.nhs.uk/long-read/five-years-greener-nhs-progress-forward-look/ (primary; source for the progress and funding figures: 14% / 68%, estate emissions, £1.4bn PSDS, £135m, gas at ~40%) 

• NHS England, 2027 NHS carbon reduction plan requirements for the procurement of NHS goods, services and works, https://www.england.nhs.uk/long-read/2027-nhs-carbon-reduction-plan-requirements-for-the-procurement-of-nhs-goods-services-and-works/ (primary) 

• NHS England blog, £100 million funding from Great British Energy for NHS trusts to install solar panels and battery storage (March 2025), https://www.england.nhs.uk/blog/100-million-funding-from-great-british-energy-for-nhs-trusts-to-install-solar-panels-and-battery-storage-systems/ (primary) 

• NHS England, Delivering a Net Zero NHS / Greener NHS (net zero 2040 for the NHS Carbon Footprint; 2045 for the NHS Carbon Footprint Plus) (primary) 

• NHS England, Green plan guidance (Green Plans required of trusts and ICBs under the Health and Care Act 2022), https://www.england.nhs.uk/long-read/green-plan-guidance/ (primary) 

• Design and estates commentators (AHR, Ridge, Architects' Journal) on the Standard's treatment of refurbishment, the reuse-first embodied-carbon hierarchy, and refurbishment derogations (wider/opinion; used for the existing-buildings framing, not for hard figures) 

• NHS-owned procurement bodies (NOE CPC / NHS Shared Business Services), decarbonisation of estates framework agreements (reported at around £1bn, running from 1 October 2026) (close/trusted; figure reported, confirm exact value against the framework notice at publish) 
• IHEEM, "New much-anticipated NHS Net Zero Building Standard published" (22 February 2023), https://www.iheem.org.uk/new-much-anticipated-nhs-net-zero-building-standard-published/ (wider/trade)