Picked up this intriguing snippet from someone who works for Sheffield Insulation, our largest supplier of insulation for the construction industry. He said that insulation sales were up by about 5% as a result of the changes brought about in 2006 by Part L revision. In theory, they should have increased by a lot more.
Also on a similar theme, a prominent boiler manufacturer tells me that sales of non-condensing boilers, which should have been kicked into touch for all time by Part L changes, are in fact holding up well. Many installers are still quite happy to fit whatever the householder wants. As far as the replacement boiler market is concerned, Part L compliance is optional, as there is no way of enforcing it.