To ask the Secretary of State for Environment, Food and Rural Affairs if he will reconcile the carbon emission factor for grid electricity shown in the Carbon Dioxide Calculator, Public Trial Version, Data, Methodology and Assumptions Paper of June 2007 of 0.527 Kg carbon dioxide/KWh and that shown in the Government's Standard Assessment Procedure for Energy Rating of Dwellings 2005 edition of 0.422 Kg carbon dioxide/KWh. (152968)

There is no current intention to reconcile these two factors as they have been produced for different purposes.

In general terms, the carbon emission factor for grid electricity will vary from minute to minute as the fuel mix (e.g. renewables, gas, oil, coal, nuclear) and availability varies. To derive a factor for the purpose of calculations, it is therefore necessary to determine a period over which to average.

For the Act On CO₂ calculator, the purpose is to get as accurate a measure as possible for current CO₂ emissions. The factor of 0.527 kg carbon dioxide/kWh is the most recently available figure based on 2005 data from the DTI DUKES electricity supply data for major power producers and CO₂ emissions from the UK greenhouse gas inventory.

For the Government’s Standard Assessment Procedure for Energy Rating of Dwellings 2005 edition consistency of comparison over a longer period of time is important. A longer averaging period has been used. The factor of 0.422 kg carbon dioxide/kWh is based on the 2000 DTI projections for expected mix of electricity supply for the average of the Central Growth/Low Price and Central Growth/High Price scenarios between 2000 and 2010.