EIR - Carbon emissions surcharge on development

The national requirement for sustainable development in housing is now dictated by the Building Regulations and is set at what was Code Level 4. Codes 5 and 6 (zero carbon) have been dropped, but in London, through their 'mayoral status', you have set your own target at a substantially higher level than the national target. But - there is not an absolute requirement to meet this higher target. A developer can instead opt to comply with Building Regs and pay a surcharge, or carbon tax, set at £60 / tonne of additional CO2 produced per year for the next 30 years. This is supposed to be a form of carbon offset and provide a war chest for the Mayor of London to spend on remedial measures to combat the effects of climate change.



My questions are,

 

1. what percentage of development in London fails to reach the higher target level set and instead opts to pay the surcharge?
2. How much revenue does this bring in for the Mayor of London?
3. And what are the controls in place to ensure this war chest gets used appropriately? ('m not actually suggesting that there's anything fundamentally wrong with this policy, but if everybody is just paying the surcharge, that would suggest it has been set too low to act as a driver for improving the sustainability of our housing)
4. Can any other council enact a similar policy? How can London do this if the government has said "All Energy and Sustainability standards will be set at a national level and Local Authorities will not be able to exceed these national requirements"?
5. Is London unique because of its London Plan or is it because you've got a Mayor?