Washington, USA - Entrepreneur Bill Gates, co-founder of the software business, Microsoft, went on to become one of the world's richest men. So it is no surprise to learn that his home near Seattle, a 6,000 sq metre property, is estimated to be worth around one hundred and fifty million US dollars. Now the man who helped design it, James Cutler, has revealed details requested by Bill Gates.

It was decided that the house design was to be future-inspired with a vision of sustainability. Generally, people think of sustainability as including water, energy conservation, insulation, solar panels and the like. However to be truly sustainable it should also be built from reclaimed building materials. It has only recently been revealed that Gates' Pacific lodge-style mansion included a high percentage of reclaimed wood, sourced from old railway bridges.

Other features of the eco design included creating the home in an earth shelter which used the natural surroundings of the forest to reduce heat loss. A system of cisterns was used for irrigation and a man-made estuary filled with fish was also built. As expected, technology has also featured in the design with guests wearing RFID pins that automatically adjust temperature, music, and lighting based on their preferences upon entering a room. Another feature of the property which may not be considered quite so sustainable is a beach made from sand transported annually from the Carribean island of St Lucia.

The property which took seven years to build, at a cost of around sixty million dollars, has been nicknamed Xanadu 2.0 after the palatial estate of Charles Foster Kane, in the film Citizen Kane. Bill Gates, who turned sixty on October 28th this year, is now dedicated to changing the the world for the better with the charitable work of the Gates Foundation. Gates is also pro-carbon tax to help solve global warming.