The Keep, next to the University of Sussex, houses archives up to 900 years old.
It is being heated by a 300kW Herz Biomatic biomass boiler installed by Rural Energy.
The boiler is part of a programme of investment in renewable and sustainable technologies by the University that includes solar PV panels and reusing rainwater.
The biomass boiler is providing heat to maintain the archives, as well as heat and hot water for the community centre, which includes classrooms, a public reading/study room and conservation labs.
It is fuelled by woodchip and generates heat and hot water for the centre, which is set to welcome around 16,000 visitors a year.
Paul Clark, managing director of Leicestershire-based Rural Energy, said: “We are delighted to have worked on this prestigious project. Our technical knowledge and advanced design capability has provided a modern, renewable heating system for such a landmark building.
“Our biomass technology will ensure a sustainable future for The Keep, reducing its carbon footprint and saving on energy bills now and in the future.
“To ensure this, we worked closely with the construction and design teams throughout the project.”