First the twin towers of Deutsche Bank, then the Empire State Building in New York, and now Sears Tower in Chicago as well. Energy upgrade plans for well-known skyscrapers all over the world are now being made public. The project for the 442 metre-high office building, the highest in the western world, will no doubt put all previous projects in the shade.

Adrian Smith + Gordon Gill Architecture of Chicago is responsible for planning the conversion. As early as autumn 2008, it had become common knowledge that the owners and users of Sears Tower, which was built in 1973, were planning an energy upgrade. They have now decided to announce further details. Over the coming 5 years, the electricity requirement of the building is to be reduced by 80 per cent. This corresponds to an annual saving of 69 million kilowatt hours. As the news platform BusinessGreen.com recently reported, the 104 elevators in the building, among other things, are to be replaced with new models which are 40 per cent more energy-efficient. In future, the combined provision of electricity plus cooling and heating power is to be ensured by a heating power station which is to be located in the building and will be powered by fuel cells. 16,000 windows with single-pane glazing (!) will be replaced and new insulation will be fitted, as a result of which the heating energy requirement is expected to fall by half..

An intelligent lighting control system with daylight sensors is also intended to help lower the energy requirement. The water consumption is to be reduced by 90,000 metric tons per year. The most prominent "green" features will include new wind turbines on the roof and a roof garden – probably the highest in the world - which the owners want to plant on top of Sears Tower.

Altogether, the upgrade is expected to cost 350 million dollars and 3,600 new jobs are to be created. When the conversion work has been completed, practically nothing in Sears Tower will be the same as it was before. Not even the name will be retained. According to the wishes of the main user, the insurance broker Willis Group Holdings, the building is to be called "Willis Building" in future. According to an article in the Chicago Tribune, the company did not even have to transfer any money for the rights to the name. All that was needed was the promise to rent the Sears/Willis Tower in future with almost 500 employees.