Proposed new buildings regulations for 2010 look like they may include conservatories, which are currently not covered by building regulations unless they are not separated from the house by doors.
Conservatories do not currently have an energy efficiency rating in the same way that houses do. Clearly to do so would be difficult, given the amount of glass involved. It is thought that all conservatories are likely to require Pilkington K rated glass and a thickness of at least 25mm for a polycarbonate roof. It has been suggested by manufacturers that a new rating system should be put in place for conservatories.