The Chatsworth Renewable Energy Centre will be officially opened today.
Its low carbon heat and power system will feed 97% of electricity and 72% of heating to the 300-room house, garden, shops and restaurants.
The centre has been funded by an attic sale of items in 2010. It has cost more than £2.5 million to build.
The Duke of Devonshire, said: “By using funds raised from the attic sale the past is playing its part in providing Chatsworth with a sustainable future by helping reduce our carbon footprint and supporting the on-going maintenance of our woodlands and ecosystem.”