Blog written by Reg Pula, ADS Policy Advisor Defence 

As UK Defence further steps up to ensure that it is playing its part in the delivery of the UK’s climate ambitions, notably through the Ministry of Defence’s Climate Change and Sustainability Strategic Approach and recent changes in defence procurement as expressed through the Social Value Model and Carbon Reduction Plans, one clear question has arisen throughout the supply chain:

How do we measure greenhouse gas emissions in a way that is consistent across UK Defence?

A Code of Practice (CoP), co-developed by the Ministry of Defence (MOD) and the Defence Industry through the Defence Suppliers Forum, seeks to answer these questions, recognising the critical role that the MOD’s suppliers have in the race to Net Zero.

The CoP sets out defence-specific guidance for Greenhouse Gas (GHG) measurement covering the main aspects of Defence including Scope 3 emissions and encompassing all areas of Defence acquisition and support including products, systems and services as well as infrastructure and estates. The CoP’s aim is not to replicate existing guidance and requirements, but to signpost the best practice that is applicable – including the Greenhouse Gas Protocol (GHG Protocol).

Recommendations in the CoP are split across four main areas: best practice in guidance; sources for emissions factors; data collection and maturity; and organisational boundaries.

Best practice in guidance

In adopting best practice in guidance, the CoP recommends that organisations:

  • Start with the guidance in the GHG Protocol and the Scope 3 technical guide.
  • Are open and transparent in the methodology and any assumptions used so that stakeholders understand the approach being taken.
  • Follow the GHG principles including relevance, completeness, and accuracy.
  • Recognise that while capturing and reporting emissions is clearly important, it is a significant undertaking, and a balance should be struck so that effort can also be invested in developing effective emissions’ reduction plans.

Sources for emission factors

In using sources for emission factors, the CoP recommends that organisations:

  • Use the latest BEIS figures for the UK as the principle authoritative source.
  • Quote the source of any alternative emissions factors being used.
  • Use an authoritative source.
  • Signpost to any international emissions factors being used.
  • Ensure transparency in the approach taken if emissions factors are not available for a specific GHG source.

Data collection and maturity

In collecting data, the CoP recommends that organisations:

  • Are transparent in the data being used.
  • Consider their data maturity pathway.
  • Focus on those aspects of their footprint that are largest or most material and can help drive the biggest reductions.
  • Create good estimates of through-life emissions within contract requirements and use these as the basis for supplier scope calculations.

Organisational boundaries

In setting organisational boundaries, the CoP recommends that organisations:

  • Take care to specify details about planned in-service use of equipment which can then be used as the assumption for calculation of the supplier’s scope 3 emissions (category 11) and the customers scope 3 emissions (category 4).
  • Consider where primary opportunity and responsibility sits between the organisations.

Though the application of these recommendations is not a formal contracting requirement for suppliers, the CoP nonetheless can help ensure consistency across UK Defence in the measurement of GHG emissions.

It is expected that the Code will be reviewed periodically to reflect evolving knowledge in terms of good practice and any future changes to standards and regulatory requirements.

If you would like to read the Code of Practice in full or discuss any of the areas addressed in this piece, please contact Reg Pula at