Assessing Scotland’s Carbon Calculator

What is the Scottish Government’s Carbon Calculator – and why is it important?

Balancing the expansion of wind energy with the protection and restoration of peatlands is a major challenge. This is where the Carbon Calculator plays a vital role as it helps developers and consultants determine whether a proposed wind farm will lead to an overall reduction in carbon emissions.

The calculator is used to assess the net zero carbon impact, which compares the carbon costs of wind farm developments with the carbon savings attributable to the production of renewable energy.

Ensuring the calculator remains scientifically robust and practical is critical to supporting informed decision-making in Scotland’s net zero transition.

What was AECOM’s role?

As independent expert advisors, we were appointed to conduct a thorough review of the latest spreadsheet version of the Carbon Calculator, seeing that it remains fit for purpose in today’s evolving policy and scientific landscape.

To do this, we focused on three key areas:

• Scientific accuracy – evaluating whether the calculator’s emission factors, and underlying methodologies reflected the latest peatland science.

• Usability – making sure the tool was practical and accessible for developers and consultants.

• Policy alignment – reviewing how well the calculator supports Scotland’s current planning frameworks and legislation, including the National Planning Framework 4 (NPF4) and the Climate Change (Emissions Reduction Targets) (Scotland) Act 2019, which sets a key driver for Scotland to meet its carbon reduction targets.

While we provided detailed recommendations to guide future improvements, implementing updates to the Carbon Calculator was not within the scope of our commission.

An evidence-based assessment

Our first task was to engage with stakeholders and develop a research protocol. This was followed by a technical assessment of the Carbon Calculator, in which we examined each of the tool’s key components used to assess the carbon impact of wind farm developments on Scottish peatlands.

From these findings, we provided recommendations to guide policy decision makers when considering revisions to the current tool. These included fundamental questions such as:

• Is the output of the Carbon Calculator useful as a decision-making tool?

• Is the focus of the Carbon Calculator correct?

• Does the Carbon Calculator need to consider the lifecycle emissions of the wind farm, or could the focus be purely on the impact of development on peat and other carbon rich soils?

Alongside this, we carried out an evidence review, analysing the scientific literature underpinning the calculator. This involved evaluating the Peatland Code, a key framework for peatland carbon assessment introduced since the calculator’s last update.

By applying our in-depth carbon expertise, we helped ensure the assessment was rooted in the latest research and best practice, providing a strong foundation for future improvements to the tool.

Collaboration at the heart

One of the key challenges of this project was striking the right balance between scientific accuracy and usability. The Scottish Government required a tool that was scientifically rigorous, while developers and consultants needed something practical and easy to use in the planning process.

Collaboration was therefore key. We worked closely with ClimateXChange and a steering group comprising representatives from the Scottish Government, policy advisors, energy specialists and scientific experts. To gather wider industry insights, we held a dedicated stakeholder engagement workshop attended by over 30 stakeholders and two meetings with the Peatland Expert Advisory Group (PEAG).

We also liaised with our own in-house specialists and independent consultants to get user insights on the tool’s practical challenges and usability. The insights gathered fed directly into our final report, shaping the key considerations. For example, we suggested simplifying the tool by reducing the number of required input variables.

Additionally, our digital experts explored how high-resolution spatial data (HRSD) could be integrated to improve precision and proposed automation of various data inputs to enhance efficiency while maintaining scientific integrity.

Balancing renewable energy development and peatland protection

Crucially, this review didn’t just focus on carbon emissions – it also considered the wider environmental impact on peatland ecosystems. Taking a holistic approach, our assessment explored how the Carbon Calculator could better account for peatland health, biodiversity and land-use change, helping decision-makers support both climate goals and nature conservation.

By using our insights to inform future updates to the Carbon Calculator, the Scottish Government can ensure that wind farm developments on peatlands are assessed with greater accuracy and transparency. This will help maximise the climate benefits of renewable energy while protecting Scotland’s vital peatlands.