Following last month's ruling by the UK advertising watchdog that wind industry claims over carbon savings were misleading, the British Wind Energy Association (BWEA) is taking steps to agree new national carbon offset figures. The Advertising Standards Authority (ASA) ruling overturned figures that had previously been agreed between the authority and the industry. Its action followed a challenge by anti-wind group The Two Moors Campaign over figures used by Npower Renewables for the amount of CO2 saved by its proposed Batsworthy Cross wind farm in Devon. Npower Renewables had calculated its figure using a carbon emissions factor of 860g CO2/kWh, which is based on the assumption that wind displaces coal-fired generation with relatively high emissions. The calculation was recommended by the BWEA and used in its literature. The figure was obtained from a 2004 document from the National Grid Company. The Two Moors Campaign argued that the figure was out of date and that wind now displaces gas generation with a typical emission factor of around 400g CO2/kWh. After consulting the National Grid Company, the ASA concluded that the true emissions factor for wind lay between the two figures because marginal plant changes over the course of a year. The BWEA points out that in overturning the figure the ASA found the association had acted in good faith in producing its publicity material. Maria McCaffery from the BWEA says: "The industry has been pro-actively working with the ASA since the summer to agree a robust and verifiable set of figures, as well as an agreed methodology so that the new figures can be regularly updated in future."