Home to the ultramodern venues used for the Beijing 2008 Olympic and Paralympic Games, Chaoyang district has made further progress in renovating facilities and building new ones with energy efficient and eco-friendly designs for the forthcoming 2022 Winter Olympics.

The National Aquatics Center, nicknamed the Water Cube, hosted the Olympic swimming and diving events in 2008. Now it has been transformed into the Ice Cube for the curling events in 2022 with all construction projects at the venue to be completed by November.

Yang Qiyong, the venue's general manager, said that after staging a national junior curling tournament in December as a trial event, the venue can now switch between hosting summer and winter events, a significant diversification in its business operations.

The National Stadium, or the Bird's Nest, is another symbolic legacy from 2008. Its renovations in preparation for the Beijing 2022's opening and closing ceremonies will be finished by September.

Liu Xinping, director of sustainability with the Beijing 2022 organizing committee's general planning department, told China Daily in August: "By repeatedly using ready-made facilities, this innovation works well by cutting unnecessary spending while diversifying venue functions for improved post-Olympic operations."

The equally famous National Convention Center is undergoing its second phase of transformation, which is due to be completed by the end of 2021, according to the Beijing Major Projects Construction Headquarters Office.

At the National Indoor Stadium, which is also located in Chaoyang district and was used for gymnastics, trampoline and handball events in 2008, its temperature-control system and lighting are being upgraded for the men's ice hockey events in 2022.

A rash of new technologies featuring clean energy and sustainable development are being used in many venues for the 2022 Winter Olympics.

For example, the National Speed Skating Oval will replace the toxic, refrigerant Freon, which is traditionally used in such venues, with carbon dioxide to make and maintain a 12,000-square-meter ice surface for speed skating. The oval will be the first venue in the world of this size to make such adjustments.

"We are confident of making the fastest-ever ice circuit for speed skating because we are using the new refrigeration system," said Ma Jin, an engineer responsible for ice-making at the venue.

Wu Xiaonan, chairman of the oval, told Xinhua that the venue will use heat generated from ice-making to melt ice in the cistern and maintain the rink's surface. These techniques will help to save about 2 million kilowatt-hours of electricity per year.

He added that the oval utilizes artificial intelligence technologies so that it can accurately control the temperature and density of the ice and the stability of its surface. The temperature of the spectator seating area will be kept around 16 C, offering a comfortable viewing experience.

The oval has had its main structure completed and will be ready for tests at the end of this year.

In addition to events relevant to the 2022 Winter Olympics, Chaoyang district will host a series of investment promotion activities to make the functional area, where the Olympic venues are, an international high-end service cluster.

The local government said it is functioning as a broker between four newly-built buildings with an overall rentable area of 480,000 sq m, and international organizations as well as institutions and enterprises specializing in high-end business services, culture and sports, technology and finance. The Asian Financial Center, the permanent home for the Asian Infrastructure Investment Bank, is one of the buildings.

To date, a batch of well-known enterprises have set up their businesses in the area, including China Securities, Beijing North Star, China Coal Energy, ZTE, China State Construction, Sinotrans & CSC, and Aibank.

Sun Xiaochen contributed to this story.