Councils can require developers to pay into a ‘carbon offset fund’ for the carbon emissions of all new homes built. (NB the Government’s proposed Future Homes Standard may prohibit this.).
Milton Keynes carbon offset fund has achieved carbon savings totalling over 6,600 tonnes (over 7 years) and has generated more than £1 million for carbon-saving projects. (Milton Keynes population 230k) Annual figure about 940 tonnes. Update; NEF quoted (by email) 9,300 tonnes over 7 years, i.e. 1,328 per annum.
(Ashden Action 2 31 Climate Actions for Councils)