1. Methodology background

 National Statistic   
 Survey name 
 Frequency  Annual
 How compiled  Based on third party data
 Geographic coverage  UK
 Sample size 
 Last revised  28 February 2010

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2. Executive summary

This Environmental accounts Quality and Methodology Information report relates to statistics for energy, which is an important topic within the UK Environmental Accounts and aims to provide users with information on the usability and fitness for purpose of these estimates.

For further information regarding the methods and terminology used in UK Environmental Accounts, please refer to the following publications:

This document contains the following sections:

  • Output quality
  • About the output
  • How the output is created
  • Validation and quality assurance
  • Concepts and definitions
  • Sources for further information or advice
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3. Output quality

This document provides a range of information that describes the quality of the data and details any points that should be noted when using the output.

We have developed Guidelines for measuring statistical quality; these are based upon the five European Statistical System (ESS) quality dimensions. This document addresses these quality dimensions and other important quality characteristics, which are:

  • relevance
  • timeliness and punctuality
  • coherence and comparability
  • accuracy
  • accessibility and clarity

More information is provided about these quality dimensions in the following sections.

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4. About the output


(The degree to which the statistical product meets user needs for both coverage and content.)

Energy data published by UK Environmental Accounts provide an analysis of energy used, broken down by fuel type and industry.

The following energy and fuel use datasets for energy are published as part of the UK Environmental Accounts release:

  • carbon fuel use by type
  • carbon fuel use by 93 industries
  • energy use by industry, source and fuel
  • energy consumption by 13 industries (including electricity reallocated to final consumer)
  • 68 industry data – energy, emissions and output
  • energy bridge table, reconciling the national accounts measure with the Digest of UK energy Statistics (DUKES)

These estimates are updated annually (each spring) to include the most recent national accounts and fuel consumption data.

The energy data are compiled in accordance with SEEA 2003, which closely follows national accounting standards set out in the System of National Accounts 1993 (SNA 1993).

UK Environmental Accounts data covers the UK as a whole; there are currently no estimates at a regional level.

These data are used to provide information for policy-makers and analysts. The users of these energy data, in government, are the Department for Environment, Food and Rural Affairs (Defra) although other departments such as the Environment Agency and the Department for Energy and Climate Change (DECC) have also used these data in their analyses. Outside government, research organisations and academia use the data in their work on environmental impacts and sustainable development.

Timeliness and punctuality

(Timeliness refers to the lapse of time between publication and the period to which the data refer. Punctuality refers to the time lag between the actual and planned dates of publication.)

Energy consumption data are published each spring with an 18 month lag. For instance, 2007 data was first published in spring 2009. This allows estimates to be based on most recent supply and use tables, which incorporate latest national accounts information regarding the composition of the economy and latest DECC fuel use figures.

Notification of the exact date on which these data are published each year is made public approximately 3 months beforehand via the release calendar. To date, publication of these data has occurred without delay. In the unlikely event of a change to the pre-announced release schedule, public attention will be drawn to the change and the reasons for the change will be explained fully at the same time, as set out in the Code of Practice for Official Statistics.

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5. How the output is created

Step 1: Fossil fuel account

The fossil fuel account is compiled in terms of energy used, that is, it excludes double counting of the energy transformed into another type of fossil fuel or non-energy product, for example, coal to coke or Smokeless Solid Fuel, coke to coke oven gas, blast furnace gas or bitumen. This is achieved by:

  1. calculating the calorific value of all the coal and coke used

  2. reducing the total energy used in the coke production sector by the calorific value of the coke produced in the UK that year

Step 2: Primary electricity

Primary electricity sources such as geothermal energy, nuclear energy, solar, wind and hydro- electricity are added to obtain a control total for total energy used; this includes use of the (net) imports of electricity.

Step 3: Calculation of direct energy use for all sectors other than electricity generation

The accounts measure the energy used from fossil fuels plus the use of electricity from the grid (the public distribution system). However, some of the fossil fuels used by industry are used to produce electricity, some of which is then supplied to the grid – this is known as autogeneration. This energy is used by other sectors and would hence be double-counted if no adjustment were made. Total energy use equals energy from fossil fuels plus all electricity used less autogenerated electricity used. This can be explained using the following equation:

Ei = FFi tot + Elec toti - AGi own

This formula should be used where:

  • Ei equals total energy used by industry i

  • FFi tot equals fossil fuel energy used, whether for electricity production or not (including energy transformed into electricity)

  • Elec toti equals all electricity used by industry i, whether autogenerated or not

  • AGi own use equals autogenerated electricity used in the same sector (ideally this figure should exclude losses from autogeneration)

The electricity adjustments can only be made for 83 sectors because of the limitations of the input and output data that is used to disaggregate the non-industrial sector sub-totals.

The data on the amount of electricity generated by autogenerators is not very detailed and a number of assumptions have had to be made to disaggregate it to environmental accounts sectors. Note that there is also a small amount of primary electricity (hydro-electric power) generated by autogenerators, which should not be included in “AGi own use”, but as we do not know which sector is involved, no adjustment has been made.

Step 4: Calculation of direct energy use for electricity generation sector

The sector is defined to comprise the major power producers. Their use of energy can be calculated as a residual, as we have a control total for total energy used and the process mentioned in this section gives figures for all other sectors.

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6. Validation and quality assurance


(The closeness between an estimated result and the (unknown) true value.)

ONS energy data are produced by contractors, the National Environmental Technology Centre (AEA Energy and Environment), who combine the Department for Energy and Climate Change (DECC) fuel data with a range of sources, including national accounts supply and use tables (SUTs) to provide a framework for the allocation of fuel use to particular industries. Therefore, there are three factors that affect the accuracy of UK Environmental Accounts energy data: DECC fuel use estimates, AEA Energy and Environment’s process of attributing fuel use to specific activities, and the accuracy of the national accounts SUTs.

Error margins for national accounts data have not been produced, although there are estimates of error margins for the various surveys, for example, the Annual Business Survey (ABS).

Further information on the accuracy of DECC and AEA Energy and Environment data are available.

No work has been done to collate the impact of these different factors on the accuracy of estimates of energy use. However, one dimension of measuring accuracy is reliability. Table 1 shows the extent to which new information and methodology changes have caused data revisions between the most recent and earlier publications.

Coherence and comparability

(Coherence is the degree to which data that are derived from different sources or methods, but refer to the same topic, are similar. Comparability is the degree to which data can be compared over time and domain, for example, geographic level.)

Energy consumption statistics are published in more than one form. A bridging table has been published to present, in a transparent way, the differences between the figures presented by the DECC in the Digest of UK Energy Statistics (DUKES) and the national accounts measure.

National accounts measure puts energy consumption on an UK resident basis to allow for more consistent comparison with main national accounts indicators such as gross domestic product (GDP)and gross value added (GVA).

The national accounts measure differs from the statistics presented in the DUKES in that:

  • only energy that leads to emissions is included whereas DUKES includes all energy

  • fuels used by the UK fishing fleet, UK international shipping and aircraft operators, and ships and aircraft used for UK military purposes, are included, whether or not they were purchased in the UK; fuels purchased in the UK by non-resident operators are excluded

  • purchases of petrol and diesel abroad by UK motorists and road hauliers are included whilst purchases of petrol and diesel in the UK by non-resident operators are excluded

  • some fuels such as gases used by the offshore industry are not treated as fuels by DUKES but are included in the energy account

  • any energy in fuels that is transformed into another fuel type is not included, whereas both the primary fuel and the transformed fuel are included in the DUKES commodity balances

  • tars and benzoles that are created as a by-product of coke ovens are treated as energy in DUKES but not in the greenhouse gas inventory or energy account

  • non-energy uses of fuels, for example, chemical feedstocks, solvents, lubricants and road-making material, are excluded; however, energy lost through gas leakage is included

  • geothermal and solar gases are included in DUKES but not the energy account

  • the energy account does not include the losses of natural gas

  • differences in publication times may result in minor reconciliation anomalies between Office for National Statistics (ONS) and DECC energy data

Methodological improvements are made to the data each year as part of an ongoing process of review and applied to the whole time series. Therefore, data are consistent within each publication but not from year-to-year. These improvements involve data regarding use of specific fuels as well as incorporation of national accounts and other data used to establish the distribution of energy use across the industries.

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7. Concepts and definitions

Unit of measurement

The unit of measurement is tonne of oil equivalent (toe), which enables different fuels to be compared and aggregated. It should be regarded as a measure of energy content rather than a physical quantity. Standard conversion factors for each type of fuel are given in Digest of UK energy Statistics (DUKES).

Non-energy uses of fuels

Non-energy use of fuels includes, for example, chemical feedstocks, solvents, lubricants and road-making material. These uses have been excluded from the data.

Renewable energy sources

Renewable energy is defined to include solar power, energy from wind, wave and tide, hydroelectricity, and energy from wood, straw and sewage gas. Landfill gas and municipal solid waste combustion have been included within renewable energy for the purposes of defining energy sources in the context of sustainable development policy.

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8. Source for further information or advice

Accessibility and clarity

(Accessibility is the ease with which users are able to access the data, also reflecting the format(s) in which the data are available and the availability of supporting information. Clarity refers to the quality and sufficiency of the metadata, illustrations and accompanying advice.)

Energy use data and text are presented in as clear a way as possible to ensure access to as wide a range of readers as possible. Plain English definitions are given where technical terms are unavoidable.

An overview of UK Environmental Accounts can be found in Focus on Environmental Accounts.

Tables, analysis and documentation are published in the spring and autumn editions of UK Environmental Accounts.

Tables, analysis and documentation are also published in UK: National Accounts, The Blue Book.

Our recommended format for accessible content is a combination of HTML web pages for narrative, charts and graphs, with data being provided in usable formats such as CSV and Excel. We also offer users the option to download the narrative in PDF format. In some instances other software may be used, or may be available on request. Available formats for content published on our website but not produced by us, or referenced on our website but stored elsewhere, may vary. For further information please contact us by email to environment.accounts@ons.gsi.gov.uk.

General queries on energy consumption data, compilation methods, quality information or difficulties finding the latest figures can be emailed to environment.accounts@ons.gov.uk.

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Contact details for this Methodology