What are carbon emissions?

Greenhouse gases (GHGs) allow sunlight to pass into our atmosphere but stop the reflected heat from passing back out into space. Certain amounts of GHGs are useful at keeping our atmosphere within a stable temperature range and with predictable climate conditions. However, if concentrations increase, we see harmful warming of the atmosphere, climate instability and increased extreme weather events. Carbon emissions produced through human activities like industry, transport and agriculture are scientifically proven to be making this worse.

There are several types of GHG, but carbon dioxide (CO₂) is the most important by volume, so we generally use the term ‘carbon emissions’. The global warming contribution of other GHGs is typically compared to how much carbon dioxide would have the same warming effect. This is why the term ‘kg carbon dioxide equivalent’ (kgCO₂e) is used when accounting for all GHG emissions collectively.

Why is carbon important to Network Rail?

It is important for Network Rail to reduce carbon emissions to meet sustainability commitments in our Greener Railway Strategy 2025-2050 and to meet our target of Net Zero carbon emissions by 2050 (2045 in Scotland). Our target is also aligned with the UK Government’s Net Zero target.

How are carbon emissions measured for enhancement projects?

During the planning, development, design, and delivery of projects to create new railway buildings or infrastructure assets, it is important to consider carbon emissions across the full life cycle of the asset. We refer to this as ‘whole life carbon’.

Whole life carbon needs to consider carbon emissions associated with:

1. Constructing the asset, including materials used, material transportation impacts and the construction site work and temporary construction facilities (the ‘Before use’ phase);
2. Energy and water use once the asset is operating (the ‘Use’ phase)
3. Foreseeable maintenance, repair and renewal interventions across the asset service life (the ‘Use’ phase)
4. Decommissioning / disposal (the ‘End of life’ phase).

It’s important to consider and quantify all these life cycle carbon contributions when we develop and compare project options and investment decisions. This helps to identify and prioritise options that will deliver the intended project outcomes and service enhancements while having the lowest and most efficient impact on whole life carbon emissions.

These whole life carbon principles are reflected in several sources of industry best practice including:

• PAS 2080:2023 – ‘Carbon management for buildings and infrastructure’
• BS EN 17472:2022 – ‘Sustainability of construction works — Sustainability assessment of civil engineering works — Calculation methods’
• RICS Professional Standard – ‘Whole life carbon assessment for the built environment’

Project business cases should always show that the whole life carbon impact has been minimised, and the anticipated business and societal benefits of the project justify the carbon impact.

Carbon management standards for projects

If you are involved in delivering a PACE-managed project, please refer to:

• relevant sections of NR/L2/ENV/015 – Sustainability Minimum Requirements for Projects – Design and Construction
• NR/L2/ENV/125 – Carbon Management for Projects and Engineering Works

What is Network Rail’s approach to carbon reduction on projects?

Network Rail’s approach to carbon reduction on projects is focussed on:

Low carbon option selection, design and delivery: identifying, prioritising and embedding carbon avoidance or reduction opportunities into the planning, design and delivery for all new assets and projects, including for example:

• Avoiding heavily constructed solutions
• Changing designs to reduce embodied carbon characteristics
• Adopting low carbon, sustainable construction materials
• Improving operational energy efficiency features in the design
• Switching to renewable energy sources

Low carbon procurement: embedding low carbon requirements into procurement processes for all relevant carbon intensive goods (material and products) and services. We want to work collaboratively with our supply chain to consider opportunities for whole life carbon emissions reduction, from tender all the way through procurement, contract award, and into contract delivery.

Roles and responsibilities for carbon management

An important aspect of carbon management on projects is to agree and communicate who is doing what, including where duties are delegated to suppliers. A RACI matrix template is attached to assist with this exercise.

Enhancement Project Carbon Management RACI Matrix template v1 Nov25 (.docx)

Which tools can be used for quantified whole life carbon assessments?

Only Network Rail approved carbon assessment tools are to be used to assess quantified whole life carbon emissions. The list of approved carbon assessment tools is below:

• RSSB Rail Carbon Tool
• eTool LCD
• OneClick LCA
• CarboniCa

If a project team wants to use a new tool for the first time, they must apply to Network Rail using the approval request template attached. Once endorsed by Network Rail, the tool will be added to the approved tools list and may be used by other projects until further notice.

Application for Network Rail approval of a carbon assessment tool (.xlsx)

It is also important to consider the naming of project carbon assessments in a way that helps clarify the location and types of rail assets involved. Arrangements also need to be made to provide read-only access to Network Rail staff with a legitimate interest in the carbon data contained within project carbon assessments. Guidance on these considerations is attached.

Carbon Communication – Improving Network Rail Access to Rail Carbon Tool Projects (PDF)

Preparation of Carbon Management Plans

Formal Carbon Management Plans (CMPs) are a critical output for enhancement projects to support business case submissions and in the form of a final as-built carbon report at practical completion. We have adopted the DfT’s CMP template to ensure we align with their business case expectations. The DfT CMP template is attached.

DfT Infrastructure Carbon Management Plan Template (.docx)

Further Network Rail guidance on carbon reduction for projects

Guidance documents are being created to support carbon management. The ‘Managing whole life carbon in infrastructure’ guidance note can be found on the Guidance notes page.

RS_ENV_ECO_GUI310 – Route Services – Carbon Reduction & Assessment Guidance – V2 (PDF)

Can’t access the link to a Network Rail standard?

If you’re an external contractor, please use the supplier portal to access Network Rail Standards. If you do not have an account you can request this using our Network Rail Standards Account Request form.

Related pages

Supporting the Delivery of Net Zero