What are the changes in the new Part L of the UK Building Regulations?

Question

Could someone give a brief summary of the changes in different aspects of the building design (e.g. insulation, airtightness etc.)?

Answer 1

If you go here http://www.energysavingtrust.org.uk/housingbuildings/publications/?mode=search&keyword=CE137 there's a list of related documents and the changes to Part L of the Building Regs are summarised on this page - http://www.ihbc.org.uk/context_archive/70/partl/prtl.html

Please add more details if you need anything specific, my girlfriend is an architect but she's out shopping at the moment.