What happened
Audit Wales, the public spending watchdog, published a follow-up on public sector decarbonisation, Zeroing in?, on 2 November 2026. As Mark Palmer reported for BBC News, it found that the "collective ambition" for a net zero public sector in Wales by 2030 is unlikely to be met, and that decarbonisation has fallen down the priority list since its last report in 2022. The main points, checked against the report:
- Emissions: 82 public bodies reported 3.96 million tonnes CO2e to the Welsh Government in 2024-25, up 20% since 2021-22. Better coverage explains part of the rise; for the 67 bodies that reported in both years the increase was 18%.
- Supply chains dominate: Scope 3 was 84% of reported emissions and supply chain emissions alone 75%. Scope 1 and 2, the heating, electricity and vehicles public bodies control directly, were 16% and barely changed (down 1%).
- Most supply chain figures are estimates: 92% of reported supply chain emissions were worked out from spending with standard emission factors, and 8% from supplier-specific data. Audit Wales says many bodies called the method "crude or unfair" and not accurate enough to target action.
- Cost: decarbonising Welsh council buildings alone has been estimated at £2.3 billion or more, and some bodies called their long-term cost unaffordable.
- Recommendations: to the Welsh Government, including making reporting consistent over time, agreeing how data will be verified, and setting out plans to address the limits of supply chain reporting.
What it means for your business
If you supply Welsh public bodies, expect to be asked for your own emissions. At the moment most of what a council or health board reports about its suppliers is its spend multiplied by an industry average. Audit Wales says the Welsh Government Energy Service has introduced an optional supplier data template for the 2025-26 reporting year and is encouraging public bodies to engage their top 10 suppliers by emissions. Its recommendations push in the same direction. It also notes that the health sector is further ahead on supplier-specific data.
Spend-based figures don't reward a supplier's cuts. If your contract price stays the same, the estimate stays the same, whatever you do to your vans or buildings. Real figures from you are the only way your reductions show up in your customer's report. The same applies to suppliers of public bodies in England, where DESNZ's public sector reporting guidance says Scope 3 figures improve when suppliers provide their own data.
A worked example: why a heat pump looks bad at first
Audit Wales gives the example of a public body installing heat pumps: under spend-based reporting, the spending on the installation raises its reported Scope 3 emissions in the short term, even though moving off fossil fuel heating should cut emissions over time. Here are the sums for an illustrative building that burns 200,000 kWh of gas a year and replaces its boiler with a heat pump using 60,000 kWh of electricity for the same heat.
| Line | Tonnes CO2e |
|---|---|
| Installation, £250,000 × Defra's "Specialised construction works" multiplier (0.21694 kg per £, 2023 figures), counted once in Scope 3 | 54.24 |
| Gas no longer burned, 200,000 kWh at 0.18231 kg per kWh (Scope 1, a year) | 36.46 |
| Heat pump electricity, 60,000 kWh at 0.13096 kg per kWh (Scope 2, a year) | 7.86 |
| Saving each year after the switch | 28.60 |
So even if the heat pump runs for the whole year it is installed, the body's reported emissions that year go up by about 25.63 tonnes, and the installation is paid back in carbon terms after about 1.9 years of lower Scope 1 and 2, on the 2026 government factors. If the installer gave its customer a supplier-specific figure for the job instead of an industry average per pound, the installation line could look quite different. That is the limitation the report asks the Welsh Government to address.
What to do now
- Measure your Scope 1 and 2. Twelve months of energy bills and fuel records are enough to start, and they are what a supplier template asks for first.
- Work out a share for each public sector customer. Allocate by revenue unless something better fits, and write the method down.
- Publish a Carbon Reduction Plan. It answers most public sector questions with one link. Our post on council tender carbon requirements covers what buyers ask for.
- Read the report's checklist. Audit Wales recommends public bodies use it to reflect on their own approach, so it shows what your customers will be thinking about. It is in the full report.
