Planning applications across London are failing to fulfil the requirement for 20 per cent renewable energy, mayoral planning adviser Sir Simon Milton has claimed.

Speaking at a meeting of the London Assembly environment committee this week, he warned: "There needs to be a change in the mindset of development communities that this is not a section 106 benefit, it is core business."

A spokesman for the mayor's office explained that whereas many outline applications do not fulfil energy requirements in the London Plan, detailed applications generally do. No figures are available on the number that do not progress to the detailed stage, he added.

Milton also pledged not to cut the number of energy specialists in the planning team at the Greater London Authority (GLA) following Patience Wheatcroft's audit. He said it is unrealistic "to expect boroughs to have in-house capacity for that kind of expertise across London".

He added that universities are starting to run courses on GLA energy policies. Leeds Metropolitan University school of the built environment surveying and sustainable housing professor Malcolm Bell agreed that developers are struggling on how to meet renewables targets. "It is a big problem in urban places such as London where there are not many viable options."