Introduced by Brian White (Lab, North East Milton Keynes), the Sustainable Energy Bill as originally drafted would have obliged the Government to report annually to Parliament on a raft of targets (ENDS Report 339, p 40 ).
The Bill faced opposition from the Government, and at one point seemed likely to be blocked altogether. It passed Committee stage in the Commons in a substantially watered down form, with all references to specific targets removed (ENDS Report 343, pp 34-35 ).
In the Lords, Baroness Wilcox (Con) commented that the amendments had left the Bill "completely emasculated" and reduced the Government's duty to report annually to Parliament to "meaningless waffle".
In response to pressure in the Lords, Environment Minister Lord Whitty promised that the Government will report on energy efficiency in the commercial, business and industrial sectors, in addition to domestic properties.
Andrew Warren of the Association for the Conservation of Energy described the Act as a "tremendous victory", arguing that it had prompted the Government to translate a "wishy-washy" aspiration into a firm commitment.
The energy White Paper had suggested that improvements to domestic energy efficiency were "expected" to contribute emission reductions of 5 million tonnes of carbon (mtC) by 2010, while another 4-6mtC "can come from households" by 2020 (ENDS Report 338, pp 26-32 ).
However, the website of the Government's new Sustainable Energy Policy Network now describes these savings as a "commitment" - a shift in language which was confirmed by Lord Whitty in a parliamentary answer on 27 October.
The new Act requires the Government and the Welsh Assembly to each set at least one "energy efficiency aim". Mr Warren believes that these will correspond to the newly firmed-up commitment.
The Act also obliges the Government to set targets for its own use of combined heat and power, requires energy regulator Ofgem to carry out impact assessments of its proposals, and earmarks £60 million of surplus cash from the non fossil fuel obligation for renewables capital grants.