The following links give additional details on the regulatory environment relating to energy efficiency and Carbon Reduction.
http://www.opsi.gov.uk/acts/acts2008/ukpga_20080027_en_1
http://www.opsi.gov.uk/acts/acts2006/pdf/ukpga_20060046_en.pdf
http://www.decc.gov.uk/en/content/cms/what_we_do/lc_uk/crc/crc.aspx