For residents, that should mean lower energy bills and warmer houses. but a report out today has calculated that doing what's needed will cost billions, as our environment correspondent sally bowman reports. council tenant kevin hill knows how lucky he is. external wall cladding with new doors, windows, etc. taking the roof right off. as part of the city's drive to become the uk's first carbon neutral city by 2028, kevin's 1970s home in radford, nottingham, is one of 77 to have what is called a deep energy retrofit. my electric has gone from about £14 a week to £17, £18 per week. but 77 hou...