The following table shows the various conversion factors that have been used throughout the EnergyHub to convert energy consumption figures into associated CO2 emissions and cost.

Fuel Type CO2 conversion factor
(kg CO2 per kWh)
Cost conversion factor
(£ per kWh)
Mains Gas 0.18404 0.0464
Electricity 0.44548 0.1532
Oil 0.24555 0.0602
Coal 0.33996 0.0369
Economy 7 0.44548 0.0908
Petrol 0.23394 0.1346
Diesel 0.12654 0.1240


Over the years, the administrative boundaries of the UK change. Since 2008, certain Local Authority mergers have ocurred. Also, for the 2011 census, the MLSOAs and LLSOAs were adjusted, so that they continue to be regions of approximately constant population. As a result of this, a small number of these regions were merged or split, and a very small number underwent complex changes in terms of their constituent output areas (OAs). DECC energy data up to and including 2011 is defined for 2001 census boundaries. From 2012, it will reflect the 2011 census boundaries.

Where available, 2011 census data is used for population and households. Therefore 2001 census data is only present where it refers to regions that ceased to exist for the 2011 census.

As a result of the boundary changes, there are effectively some new (2011 census) and some old (2001 census) MLSOAs and LLSOAs, while the majority are valid for both census periods. The EnergyHub database contains all the regions from both periods, and all energy data defined for them. Therefore, for a given year and for a given region, the data you will find here will be accurate.

However, it is important to understand that EnergyHub does not contain a facility to relate new administrative regions to old ones. This is because the boundary changes are relatively small. However, this means that a time series for a group of MLSOAs or LLSOAs may not be representative if splits or mergers have ocurred in that group.

This also means that the mapping between LLSOAs and MLSOAs is correct for the 2011 boundaries, and hence some 2001 mappings are not retained. Therefore you may not be able to 'drill down' into some MLSOAs, if these have been redefined for the 2011 cenusus, but the constituent LLSOAs are from the the 2001 boundaries. This issue disappears for 2012 (or later) data, and hence only affects historical analysis.

At a level of Local Authorities, for a given year their data is aggregated from the MLSOAs that they contained that year. Therefore despite the boundary changes, time series for such regions will remain accurate. Local Authorities themselves have changed over the years. The 2008 boundaries are used throughout the period we present data for, with data from earlier Local Authorities that underwent mergers aggregated appropriately.

A final complication is that the central heating data is defined for the 2011 census boundaries. There is an option in the mapping interface to display the new regions from 2011 whereas by default they will only be displayed from 2012, to reflect the year that DECC energy data moves over to the 2011 census boundaries.

Detailed information on how the output areas changed for the 2011 census is available here. For more detailed information on any of this, you should contact us.