The National Trust is to make its “biggest ever” investment in renewable energy, pledging £30 million to install various generation technologies across its estate.

The charity owns and maintains places of historic interest or natural beauty throughout the UK and announced the commitment today during the launch of a biomass boiler at Ickworth in Suffolk, which was attended by energy and climate change secretary Amber Rudd.

The National Trust now hopes to reduce its energy usage by 20% and generate half of its energy demand by 2020, efforts which it believes could help it save around £4 million each year in energy costs.

The programme is to expand on a £3.5 million commitment made with utility Good Energy in 2013 and Patrick Begg, rural enterprises director at the National Trust, said the long-term decisions it was making formed part of its “responsibility to look after the special places” in its care.

“Many of the properties in our care are energy intensive and in remote areas without access to mains gas. Installing renewable technology in these places is a huge challenge, but we’ve learnt a great deal and will continue to do so.

“The success we’ve seen in decommissioning oil tanks, lowering our energy costs and reducing carbon emissions has shown us that renewables play a vital part in us reaching our 2020 energy targets and in delivering more for our core conservation mission,” Begg said.

More than 40 projects are to be pursued across the Trust’s estate, including additional biomass boilers at Upton House in Warwickshire and a 250kW hydro scheme at Hayeswater in Cumbria.

“It’s been fantastic to see how renewable projects like the biomass boiler at Ickworth are transforming the energy use of some our oldest and most special buildings. The National Trust is truly inspirational with this approach,” Juliet Davenport, chief executive at Good Energy, said.