Improving how we measure carbon emissions

Steve Elderkin, National Highways Director of Environmental Sustainability, sets out our approach to refining carbon data and our commitment to openness and transparency in reporting.

We published our Net zero highways plan in July 2021. The plan sets the direction for the our decarbonisation journey and two years after publication we remain just as committed to it.

We're making good progress towards the three key targets of reducing our:

  • operational emissions to net zero by 2030
  • construction and maintenance emissions to net zero by 2040
  • road user emissions to net zero by 2050

But two years on, we know more than we did when the plan was written. Just as is the case for most organisations implementing net zero plans, we are learning a lot.

This is because when an organisation sets out to reduce its emissions, it must start by asking ‘where do emissions come from?'.

By answering this question, we can also determine:

  • a realistic and ambitious decarbonisation target?
  • what needs to be done and when to reduce emissions to meet this target?

To develop the Net zero highways plan, we needed to create a ‘carbon baseline’ of where our emissions come from. We knew we didn’t have perfect data, but used the best available information to develop our plan.

As we've embedded the plan across our organisation, we've also improved our collection and processing of carbon data. We now know more about where our emissions come from.

We were right not to wait for perfect data before starting our net zero efforts. However, we are now:

  • more confident about where our emissions come from
  • increasingly confident that we are targeting our efforts in the right places
  • better at projecting the future trajectory for our emissions

Science Based Targets initiative (STBi) standard

Our targets were set following the SBTi Net Zero Standard. This is the recognised standard to measure net zero for organisations.

The SBTi standard also provides guidance on how to revise an organisations carbon baseline.

By re-baselining, an organisation can integrate the latest and best information into its net zero highways plan. An organisation may undergo structural changes, altering the scope for what should be included. More accurate data may help produce more precise estimates.

We recognise that it's best practice for us to make this update and be transparent about doing so. As our Net Zero plan stated:

“Reducing emissions to net zero is a journey. Over time new solutions will become available and the path will become clearer. This plan provides a snapshot of what we intend now. We will use a process of continual improvement to refine our course into the future”.

We have also committed to:

  • review our data systems
  • develop a plan to upgrade our processes, systems and assurance by the end of 2024

Our updated carbon baseline

The publication of our Net Zero Plan Second Progress Report gives us a good opportunity to publicly and transparently update our carbon baseline.

We've moved from a calendar year (2020) to a financial year (2019/20), reflecting all our other external reporting.

We've also included better estimates for our emissions. We think our baseline operational emissions were higher than we originally estimated by nearly 30,000 tCO2e.

Half of that increase comes from the inclusion of emissions from our leased assets, but with other increases in our estimates for electricity related emissions and corporate purchases.

Conversely, our estimate for baseline construction emissions is now lower by over 100,000 tCO2e. Our use of cement and concrete remains the biggest contributor. We now estimate that a higher proportion (over two thirds) of our construction and maintenance emissions were embedded in the materials we used.

This makes it more important than ever for us to:

  • focus on our actions to reduce material use
  • decarbonise those materials we do use

Against this revised carbon baseline for 2019/20 we have estimated our emissions for the latest reporting year 2022/23. To be comparable, these were calculated on the same basis as the revised carbon baseline.

We see a reduction in all three categories. Operational, construction and road user emissions are all lower in 2022/23 than in the baseline year of 2019/20.

There is a long way to go, but we are moving in the right direction.