Constructors work on the site of a central cooling system in China (Guangdong) Pilot Free Trade Zone Qianhai & Shekou Area in Shenzhen, south China's Guangdong Province, March 15, 2019. Shenzhen has started to replace separate cooling systems in buildings with underground central cooling system to promote green development. (Xinhua/Liu Dawei)

Constructors work on the site of a central cooling system in China (Guangdong) Pilot Free Trade Zone Qianhai & Shekou Area in Shenzhen, south China's Guangdong Province, March 15, 2019. Shenzhen has started to replace separate cooling systems in buildings with underground central cooling system to promote green development. (Xinhua/Liu Dawei)

Constructors work on the site of a central cooling system in China (Guangdong) Pilot Free Trade Zone Qianhai & Shekou Area in Shenzhen, south China's Guangdong Province, March 15, 2019. Shenzhen has started to replace separate cooling systems in buildings with underground central cooling system to promote green development. (Xinhua/Liu Dawei)

Constructors work on the site of a central cooling system in China (Guangdong) Pilot Free Trade Zone Qianhai & Shekou Area in Shenzhen, south China's Guangdong Province, March 15, 2019. Shenzhen has started to replace separate cooling systems in buildings with underground central cooling system to promote green development. (Xinhua/Liu Dawei)

Constructors work on the site of a central cooling system in China (Guangdong) Pilot Free Trade Zone Qianhai & Shekou Area in Shenzhen, south China's Guangdong Province, March 15, 2019. Shenzhen has started to replace separate cooling systems in buildings with underground central cooling system to promote green development. (Xinhua/Liu Dawei)