While there are already standards for measuring and monitoring GHG emissions and for doing energy audits, PAS 51215-1:2025 is the UK’s first national standard for carrying out a combined assessment to identify and evaluate the costs and benefits of options for organizations to decarbonize to meet net zero.
PAS 51215-1 is to be used by ESOS lead assessors to conduct energy and decarbonization assessments that comply with updated requirements for Phase 4 of the UK Energy Savings Opportunity Scheme (ESOS).
In addition, PAS 51215-1 can be used by organizations of any size that want to carry out an assessment to identify improvement opportunities to decarbonize and reach net zero by 2050 or before. Users will include:
• assessors, teams of assessors, and those who lead a team of assessors of energy and GHG emissions, who might be internal or external to your organization;
• organizations that commission assessments;
• regulators (national, regional and local);
• training providers;
• professional associations, NGOs and academia.
It specifies process requirements for conducting an energy and decarbonization assessment, as well as the output of such an assessment. The process set out in PAS 51215-1:2025 includes:
- the identification of opportunities to improve energy performance and reduce greenhouse gas (GHG) emissions, and
- the production of an implementation plan for achieving net zero within the boundary of the assessment.
PAS 51215-1:2025 covers the process necessary for the assessment of an organization’s energy use and GHG emissions. Assessments for which this process is relevant relate to energy use and to GHG emissions for which the organization is responsible and which are covered by:
a) the organization’s energy consumption and energy-related Scope 1 and 2 emissions from the organization’s assets and activities, including buildings, transport and industrial processes;
b) the energy consumption and Scope 3 emissions from business travel; and
c) any additional Scope 1, 2 and 3 emissions that the organization that is being assessed wishes to include.
NOTE: PAS 51215-1:2025 does not cover the implementation of recommended improvement opportunities, the environmental disclosures of the organization being assessed, or verification that the organization being assessed has achieved carbon neutrality or net zero status. The PAS also does not cover offsetting residual GHG emissions.
— Net zero. All sectors of the economy need to rapidly reduce GHG emissions to ensure the UK as a whole is net zero by 2050. PAS 51215-1:2025 is an effective tool for helping organizations meet their share of that target as well as tackle climate change.
— Practicality. PAS 51215-1:2025 gives you a clear and easy-to-follow process for conducting robust energy and decarbonization assessments.
— Efficiency. It harmonizes energy and decarbonization assessments into one process, saving time, effort and cost.
— Effectiveness. PAS 51215:2025 proposes an overall implementation plan for net zero, avoiding the adoption of piecemeal, disjointed and short-term initiatives that can ultimately limit or hinder your ability to achieve net zero by 2050.
— Utility. It increases the visibility, transparency and comparability of assessments and of quantified improvement opportunities, thus helping with decision-making, accountability, responsibility, credibility, collaboration, climate-action progress tracking, engagement, and trust.
— Quantification. PAS 51215-1:2025 quantifies improvement opportunities, helping you prioritize actions; allocate resources effectively; commit to long-term sustainability planning, strategies and policies; and set clear goals and realistic targets that manage expectations.
— Authority. PAS 51215-1:2025 was commissioned by the Department of Energy Security and Net Zero and produced, via widespread expert consultation, by the UK’s national standards body – so it’s thorough, authoritative and trustworthy.
— Confidence. It gives organizations confidence that improvement opportunities are relevant and fit for the intended purpose or application.
— Sustainability. PAS 51215-1:2025 can help your organization develop emissions reduction expertise and ensure that future growth is sustainable.
When the Energy Saving Opportunity Scheme (ESOS) was first developed, the Department of Energy and Climate Change (DECC) sponsored the development of PAS 51215:2014 to establish competencies for lead assessors conducting an ESOS assessment.
The Department of Energy Security and Net Zero (DESNZ) has subsequently sponsored BSI’s revision of PAS 51215:2014 into two documents: PAS 51215-1 and PAS 51215-2. In effect, PAS 51215-1:2025 is a new standard, while PAS 51215-2:2025 updates and replaces the withdrawn PAS 51215:2014.