3 years ago I met David Miliband, then Energy Secretary, at the Hay Festival. He is actually very approachable, although personally, I am more likely to vote for his brother Ed who has been a far more effective Energy Secretary since 2007. In the discussion I told Mr David M that the zero carbon target for 2016 was impossible, it is too tough a standard for 100% of homes to meet, both technically (systems etc), environmentally (microclimate effects in high density cities) and economically (getting builders to do it affordably!). Being in the trade, I know how impossible a target it is to meet in any one of those areas. Unless you build freakishly specialised houses like Hockerton, it ain't gonna happen!
He persisted in parroting the official 2016 line.
This new decision is not a backing down, it seems more like getting to grips with reality. The idea of softening the target was mooted a month ago (27 July), but it would be done by getting builders to pay into a Carbon Offsetting fund, a bit like air travellers paying into a tree planting website to overcome their guilt for flying - but even this is too difficult for housebuilders, it will still put the cost up, and are there enough tree planting schemes to absorb all that money?
The previous 2016 target was as dogmatic and untested as Blair's idea of 50% of the population going to University, but then bumping the fees up astronomically. It is actually considerably more difficult than Kennedy's famous ten year promise to send a man to the moon by 1970.
btw, This is an interesting site: http://www.zerocarbonhub.org/