The GHGI and AQPI are compiled and reported consistently with international guidance from the IPCC and EMEP-EEA.
To produce the emissions estimates, Ricardo collect and analyse information from a wide range of sources – from national energy statistics through to data collected from individual industrial plants.
For insight into the organisational structure of the UK National Inventory System, including a summary of key stakeholder organisations and their respective roles and responsibilities, visit the NAEI system page.
Process of inventory preparation
The following activities are carried out each year as the inventory is compiled:
| Step | Task | What is involved |
|---|---|---|
| Step 1 | Method improvement | Improvements to calculation methods are normally implemented before the inventory is compiled. These improvements may be based on recommendations of UNFCCC (Centralised Reviews, In Country Reviews), bilateral and peer reviews and relevant research sponsored by DESNZ, Defra or other organisations via the NISC and UK GHG Inventory improvement programme. |
| Step 2 | Data requests | Requests for activity data and background data are issued to a wide range of data suppliers. Each request is issued with a unique code, and a database is used to track the request and the data supplied from that request. |
| Step 3 | Data verification | Activity data received are examined. Anomalies are investigated, such as time series discrepancies or large changes in values from the previous to the current publication year. |
| Step 4 | Data processing | Data are prepared to allow emissions of direct and indirect GHG to be estimated. |
| Step 5 | Emission estimation | Provisional emissions are estimated using the most recent activity data available. |
| Step 6 | Quality Checking Routines | A series of quality checking routines are conducted to detect anomalies in the estimates (such as time series variations, year to year changes and outlier implied emission factors). Errors and omissions are then rectified. |
| Step 7 | Emissions reporting (including background data) | Estimates of emissions are prepared for the various reporting formats (e.g. IPCC, UNECE etc.). |
| Step 8 | Report generation | Draft reports are written to satisfy the reporting criteria of the various agencies, e.g. the UNFCCC. |
| Step 9 | Report review | The reports are reviewed: internally; by external contributing agencies; and by DESNZ. Errors and omissions are then rectified. |
| Step 10 | Report publication | Final reports and data sets are then submitted and published in print and on publicly available web sites. |
| Step 11 | Data archiving | At the end of each inventory cycle, all data, spreadsheets, databases and reports are archived, allowing all data to remain traceable, should it be needed in future years. |
The system outlined above complies with the Tier 1 Quality Assurance and Quality Control (QA/QC) procedures, as outlined within the 2006 IPCC Guidelines (IPCC, 2006).
Continuous improvement
Continuous improvement of the inventory is delivered through a programme of review of inventory data followed by a programme of targeted research. This is possible through maintaining an on-going "live" list of comments, improvements and issues that the inventory team find at any time during the inventory cycle.
In addition, there is a broader programme of activities, which contribute to the identification of improvement options:
- Attendance at technical national and international workshops, conferences and meetings such as the TFEIP/UNFCCC
- Ongoing data collection and inventory compilation
- Ongoing stakeholder consultation
- Assessment of results from the annual uncertainty assessments
- Recommendations from external and internal reviews
- Inconsistencies identified in verification work
The NAEI team also include specific improvement feedback from the wider user community including users of data for modelling and Local Authority review and assessment work.
An improvement list identifying inventory improvement research projects is compiled and prioritised in consultation with DESNZ/Defra in April of each year. The improvement list predominantly covers items which could feasibly be undertaken as part of the core inventory improvement work. Additionally, it includes complex, technical research programmes involving in-depth investigation of individual sources (for example through in-situ measurements) that would require different project teams and alternative funding.
For ongoing improvement items that will feed into future submissions, please refer to the National Inventory Report for GHGI improvements, and the Informative Inventory Report for AQPI improvements. These can be found on the Reports page.
EMEP/EEA and the IPCC describe a minimum acceptable level of QA/QC and the UK emissions inventory team aim to exceed these baseline requirements. In addition to the UK’s own GHGI and AQPI specific QA/QC system, through Ricardo, the Inventory has been subject to ISO 9000 since 1994 and is now subject to ISO 9001:2015. It is audited by Lloyds Register Quality Assurance (LRQA) and the Ricardo internal QA auditors. The NAEI has been audited favourably by LRQA on five occasions in the last 15 years. The emphasis of these audits was placed on authorisation of personnel to work on inventories, document control, data tracking and spreadsheet checking and project management. As part of the Inventory management structure there is a nominated officer
responsible for the QA/QC system - the QA/QC Co-ordinator. As part of the Ricardo group certification, Ricardo is currently accredited to ISO 9001:2015. Lloyds Register Quality Assurance carried out a threeyearly recertification audit of Ricardo which was completed in October 2022. Ricardo successfully passed the recertification, with no major non-compliances, and a new Ricardo Group certificate was issued in February 2023. Under the Ricardo Group certification Ricardo is currently certificated both for the Quality Assurance ISO 9001:2015, Environmental Management System ISO 14001: 2015 standards and Health & Safety ISO 4500:2018 standards
Inventory Cycle
The NAEI is compiled on an annual cycle that encompasses: data collection, compilation, reporting, review and improvement. Each year the latest set of data are added to the inventory and the full time series is updated to take account of improved data and any advances in the methodology used to estimate the emissions. Updating the full time series, making re-calculations where necessary, is an important process as it ensures that:
- The full NAEI dataset is based on the latest available data, using the most recent research, methods and estimation models available in the UK
- The inventory estimates for a given source are calculated using a consistent approach across the full time-series and the full scope of pollutants
- All of the NAEI data are subject to an annual review, and findings of all internal & external reviews and audits are integrated into the latest dataset
End users
The end user calculations allocate emissions from the production and processing of fuels (including the production electricity) to the consumers of these fuels to reflect the total emissions relating to that fuel use. This is in contrast to the 'by source' emission reporting in which emissions are attributed to the sector that emits them directly.
One example of an end user is the residential sector, emissions in this sector include:
- direct emissions from domestic premises, for example, from burning gas, coal or oil for space heating.
- emissions from power stations generating the electricity used by domestic consumers; emissions from refineries including refining, storage, flaring and extraction; emissions from coal mines (including emissions due to fuel use in the mining industry itself and fugitive emissions of methane from the mines); and emissions from the extraction, storage and distribution of mains gas.
The UK end user model has been used by policy makers in the United Kingdom to understand the interactions between the energy transformation industries and their effect on greenhouse gas emissions.
Get data
UK end user emissions statistics from the NAEI form part of the Accredited Official Statistics, published by Defra and DESNZ on an annual basis. Statistics related to air quality emissions can be found on Defra website and statistics for greenhouse gas emissions can be found on the DESNZ website.