At the Lake District site, the firm has helped install a woodchip boiler, which generates heat for the Bowe Barn and reduces the carbon output of the National Park.
One the Isle of Wight, npower has worked with the Green Energy Fund to install solar thermal panels on the National Trust-owned home, which will provide hot water for the household and help to reduce its overall energy bills.
Tony Tutton, the National Trust's property manager on the Isle of Wight, said: "It's great to be able to use this money from npower to help make energy saving changes to our properties here on the island, not only increasing their efficiency in terms of carbon use, but also saving money for the people living in the houses."
npower recently announced that Wallace and Gromit would be the faces of its new energy efficiency campaign, which aims to teach homeowners about the value of energy usage.
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