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Doesn't the London Plan already contain environmental demands?

It does, notably in requiring developments to cut carbon emissions by 10% by generating renewable energy on site.

Isn't that tough enough?

Mayor Ken Livingstone doesn't think so. A review of the plan has come up with an even tougher demand, under which developers will have to cut carbon emissions by 20% by generating renewable energy on site.

Is that the only new measure to make London greener?

The more stringent on-site energy generation target is one of several measures. There is a proposal to set overall carbon dioxide reduction targets, rising from 15% by 2010 to 30% by 2025 and 60% by 2050. Developers will be required to use "decentralised" energy supply, such as combined heat, power and cooling systems.

Is there more?

The mayor will work with boroughs and other agencies to achieve other objectives, including:

• Ensuring a development is located, designed and built for the climate it will experience over its lifetime and capable of adapting to new uses.
• Increasing cost-effectiveness and providing incentives to use technologies to help address climate change.
• Procuring and using building materials more responsibly.
• Managing flood risk through policies on the location, design and construction of development.
• Minimising overheating within buildings by, for example, encouraging green roofs and walls and designs to reduce solar gain.
• Minimising movement of waste.

Last month the GLA published supplementary planning guidance on sustainable design and construction.

What does mayor Ken Livingstone say about it?

"The new policies … set tough but deliverable targets… We must move our cities away from relying on inefficient centralised heat and power generation, and stop constructing buildings that waste heat and electricity."

What happens now?

Draft further alterations to the London Plan will go out to public consultation in the autumn, and could come into force in 2008.