Work to build the core area of the capital's central business district (CBD), which includes 18 new low-carbon buildings, will start on Thursday, a city official has announced.

"Preparation for the design and demolition, which started in March last year, has finished," Wu Guiying, Chaoyang district's executive deputy governor, said on Sept 13. "Construction on the (30-hectare zone) should be completed in 2015."

Wu, who is also director of the CBD administrative committee, was speaking at a news conference ahead of the 11th annual CBD Business Festival on Sept 15.

When finished, the zone will be home to the headquarters of 27 companies, including China Minsheng Bank and China Investment Corp, while it is also expected to attract investment of 100 billion yuan ($15.6 billion), with annual tax revenue of more than 50 billion yuan.

A total of 18 new buildings will be built, with companies set to sign low-carbon pledges on Thursday to show their determination to saving energy, land, water and other resources.

"Our goal is to save 65 percent of energy in the construction and maintenance of the buildings," Wu said. "Companies working in the zone should also be from low-carbon emission industries, such as finance and insurance, and be regional headquarters of international companies."

One of the green structures will be Beijing's latest skyscraper, a 510-meter office tower owned by CITIC Group that will have 104 floors above ground and four basement levels.

The final design for the core area, chosen from 203 options provided by 60 domestic and overseas agencies, will be unveiled during the festival, Wu said.

Work on the underground section, which will go down five levels and connect all 18 buildings, has already started. The project includes parking lots and emergency escape routes and will cost 4 billion yuan.

"People can drive underground from one building to another after the construction, which will definitely alleviate traffic above ground," Wu said.

An estimated 80,000 to 100,000 people will work in the core area, with 85 percent expected to commute using public transport, he said.

More than 180,000 people already work for about 15,000 companies in the CBD, making traffic congestion a pressing issue. Three new subway lines and three new bus stations will be built in the zone by 2015, Beijing Youth Daily reported. The west-to-east Line 6 will be put into use next year.