Over the next five years the National Trust aims to renovate more than 5,000 buildings to meet a set of minimum environmental standards that include installing maximum loft insulation, water saving devices, rainwater storage, double or secondary glazing, thermostatic heating controls and efficient lighting systems.

With building stock that includes castles, farm cottages, lighthouses, pubs, urban terraced houses and churches, the Trust has an eclectic portfolio of heritage properties.

Overseeing this plan of works is Stephen Kane, Deputy Head of Buildings at the National Trust. He says: "What we’ve realised is that we need to start adapting our buildings now in order to be able to survive the conditions we are going to face in the future. But it’s not going to be easy and we realise there are challenges ahead.

“The majority of the buildings we will be renovating are historic and with that comes with some constraints. We need to be sympathetic to the aesthetics, planning consents and historical significance. For example, we can’t put uPVC windows in the majority of our tenanted houses.”

Most of buildings owned by the Trust are Victorian or earlier, they were designed and built to perform in a different way to that which is expected of them now. Central heating, roof insulation and draft proofing all change the way the buildings perform and can impinge on their long-term integrity.

Changes will be measured, and to a degree limited, but because they are happening to such a large number of properties the overall benefits in terms of reducing the amount of carbon produced will be considerable.

Castle Drogo in Devon is currently undergoing renovations that will bring it inline with the standards. Inside a new reception building visitors will find recycled glass on the floor and rainwater water supplying the toilets. Hidden away in the roof space will be recycled newspaper, providing a greener insulation. An old inefficient oil boiler will be removed and replaced by a biomass version that will be fuelled by local woodchips.

“It’s only a mammoth task because of the number of buildings we are talking about,” says Kane.

As well as working towards achieving reductions in energy use and waste the Trust wants to use local and sustainable sources for materials and services, minimise construction waste and avoid the use of cement, CFCs, HCFCs and PVC products.

In addition, by reconnecting disused water wheels, using natural building materials, collecting rainwater on an industrial scale and working with its energy partner, nPower on installing biomass fuelled systems and solar technology, the charity is committed to finding ways to lighten its load on the natural world.