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 prominent, 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 applied when accounting for all GHG emissions collectively.

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.

The Greenhouse Gas Protocol is the most widely used international standard for accounting and reporting GHG emissions at an organisational level. The protocol classifies three major emission scopes according to where the emissions come from, and how much an organisation can control or influence the reduction:

Definition: Direct GHG emissions from sources that a company owns or controls.

Examples:

• Fossil fuel combustion in owned vehicles or on-site boilers
• GHG emissions from process equipment
• Emissions from chemical reactions in directly controlled manufacturing.

Definition: Indirect GHG emissions during the generation of purchased electricity, steam, heating, or cooling.

Examples:

• The emissions released by the power station when generating electricity that the organisation buys and uses.

Definition: All other indirect emissions that occur in a company’s value chain, upstream and downstream, that are not included in Scope 2.

Examples:

• Upstream: Emissions from the production of purchased goods and services or from the extraction and production of purchased fuels and energy-related activities
• Upstream: Emissions from the production of capital goods used in construction works
• Upstream: Transportation of purchased goods from manufacturers to places of use
• Downstream: Emissions from the use of sold products or the end-of-life treatment of those products.
• Employee commuting and business travel
• Emissions from waste generated in operations

Scope 1, 2 and 3 emissions are typically accounted for as annual emissions reporting.

The most recent assessment of Network Rail emissions has indicated the following distribution:

Scope 1: 2%

Scope 2:  2%

Scope 3: 96%

During the planning, development, design, and delivery of projects to create new railway buildings or infrastructure assets, it’s important to consider carbon emissions across which represent 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:

• Constructing the asset, including materials used, material transportation impacts and the construction site work and temporary construction facilities (the ‘Before use’ phase)
• Energy and water use once the asset is operating (the ‘Use’ phase)
• Foreseeable maintenance, repair and renewal interventions across the asset service life (the ‘Use’ phase)
• 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 whilst 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 residual carbon impact.

Network Rail’s approach to carbon reduction is focussed on the following key areas:

Low carbon rail journeys: reducing the emissions of rail journeys by minimising reliance on fossil fuels for traction power, and instead using green, renewable, low-carbon energy.

Low carbon operations and operational asset management: embedding low carbon outcomes into our operational decision making. For example:

• Minimising reliance on fossil fuels at our stations, depots, offices and our wider property portfolio
• Improving the energy efficiency of operational systems and devices
• Using energy metering data and building management systems to monitor and optimise energy use
• Incorporating low carbon innovation into renewals strategies
• Maintaining assets for longer and repurposing decommissioned assets to extend the value of resources for as long as possible and avoid the need for virgin materials
• Switching to renewable energy sources
• Transitioning our road fleet to and supporting rail systems

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.

Low carbon option selection, design and delivery of new assets: identifying, prioritising, and embedding low carbon 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

Carbon management procedures and systems: to help achieve our objective we will put in place the necessary procedural mechanisms and data management systems to inform business decisions and monitor and measure our progress.

Related pages

Supporting the Delivery of Net Zero
I need to manage carbon reduction on an enhancement project