That is the question? I don't want to bore you with the gas main and zero carbon thing I blogged about last thursday - however, I found this tasty snip:
Tony Baldry: To ask the Secretary of State for Communities and Local Government what percentage of housing in eco-towns is planned to be zero-carbon. 
Caroline Flint: As we have set out in the consultation document, “Eco-towns—Living a greener future”, the development as a whole, not just housing, should reach zero carbon standards.
Read it here: House of Commons Handwritten Answers for May 16th