Wind turbines, roof gardens and solar panels will join the pair of antennas atop the Sears Tower's staggered rooftops in Chicago, said building officials who announced on Wednesday that the skyscraper would undergo a $350m green renovation.

The five-year project would reduce the tower's electricity use by 80% and save 24 million gallons of water a year, building owners and architects said.

Separately, a 50-storey, 500-room privately funded luxury hotel with its own green components would be built next to the skyscraper within five years.

"Our plans are very ambitious," said John Huston of American Landmark Properties, who represents the building ownership. "Our plans to modernise and transform this icon will re-establish Sears Tower as a leader, a pioneer."

The environmental upgrades are the latest changes affecting Sears Tower.

In March, London-based Willis Group Holdings announced that the Sears Tower would be renamed Willis Tower later this summer after the company has moved 500 employees into the building. And construction is under way on the tower's Skydeck to add four enclosed glass-bottomed balconies.

The green project includes the installation of solar panels on the tower's 90th floor roof to heat water used in the building. Different types of wind turbines will be positioned on the tower's tiered roofs and tested for efficiency. And between 30,000 square feet (2,787 square meters) and 35,000 square feet (3,250 square meters) of roof gardens will be planted.

"This endeavour is incredibly important as a role model for others to follow," architect Adrian Smith said. "We see this as a groundbreaking opportunity."

Other changes to the 110-storey skyscraper, the tallest building in the United States, include improvements to the 16,000 window pieces along the outside of the tower to save heating energy; mechanical system upgrades; updates to the building's 104 elevators; an advanced lighting control system and restroom renovations aimed at saving water.

Officials dispelled rumors the building's black exterior would be painted silver to increase energy efficiency.

"We don't have any plans to change colors at this time," Huston said.

The project should create 3,600 jobs, officials said, and will include a learning centre on the ground floor showcasing green efforts to the public.

Sears Tower first opened in 1973, designed by the architecture firm Skidmore, Owings and Merril, the same firm that designed the city's John Hancock Tower.

Sears Roebuck and Co was the building's original tenant before the department store moved its headquarters to the Chicago suburb of Hoffman Estates in 1992. A real estate investment group formed in 2004 now owns the 1,451-foot (442-metre) skyscraper.

Officials say they'd like the tower to achieve "LEED" status, otherwise known as Leadership in Energy and Environmental Design, a standard monitored by the US Green Building Council.