Eco living: window wars at Trinity College, Cambridge English Heritage argues double glazing is a step too far in such an important monument. Earlier this month, Cambridge City Council's planning committee unanimously approved the college's plans, praising their farsightedness. However, objections by English Heritage and the Georgian Group require the Secretary of State to be notified and the National Planning Casework Unit now has 28 days to decide whether to endorse Trinity's plans or call for a public inquiry. English Heritage argues that while it supports Trinity's aims of improving energy efficiency, some proposals harm the historic significance of the building. It particularly objects to the double glazing and internal insulation which it describes as "unnecessary." "If Grade I listed buildings can't be lived in because they are too costly to heat, or are in breach of regulations, then what is their future?" asks Dr Rod Pullen, Trinity College junior bursar who is overseeing the £10 million scheme. Oliver Smith of 5th Studio, which developed Trinity's proposals, says: "This is a really big issue waiting in the wings. There are lots of privately rented flats and homes in Grade I and Grade II* listed buildings that will need radical refurbishment. We can't just stick our heads in the sand. Meanwhile, the National Trust, owner of hundreds of historic homes and privately let properties is conducting its own research into how to modernise them. "We have put LED light bulbs into chandeliers, and secondary glazing into some properties," says Keith Jones, the Trust's environmental practices adviser. We've insulated every mansion in Wales. The Trust has also installed solar thermal panels on the roof of 700-year-old Chirk Castle near Llangollen, providing hot water for residents. He says local authority conservation officers" knowledge often lags behind the rapid development of new materials. Jenny Holland of the Association for the Conservation of Energy says tenants must be protected from soaring fuel bills and the health effects of living in cold homes. "While the majority of listed properties will only require low-cost measures, there does need to be national debate about how we make historic buildings fit for the future," she says. I went to see New Court and could not tell the difference between the original single-paned windows and a "Histoglass" one. Trinity's plans are just the kind of radical and inventive ideas worthy of the great thinkers Cambridge has produced.