(Bloomberg) -- The summertime blast of hot exhaust from air conditioners onto city streets from Soho to Singapore is a global energy efficiency investment opportunity Engie SA sees hitting $70 billion next decade.

Massive district cooling projects, which use chilled water from underground facilities to provide cold air to entire city blocks, may be the way forward as governments increasingly want developers to phase out individual AC units, according to Didier Holleaux, the French company’s executive vice president. Penthouses or solar panels could also replace air-conditioners that take up space on the roofs of office buildings, he said.

The growing market for district cooling underscores how governments and developers are placing a higher premium on reducing emissions and improving energy efficiency in the wake of the 2015 Paris climate agreement. Investment in energy efficiency grew 9 percent to $231 billion in 2016, according to the International Energy Agency.

“The potential market is tens of billions of dollars, so obviously that’s an attractive market," Holleaux said in an interview in Singapore, where the company earlier this year announced plans to invest S$80 million ($59 million) over five years in the city-state to develop the Centre of Expertise for District Cooling. “In the near future, probably everything we do for cities like district cooling will be a very important line of business for us.”

Some of the most prominent examples of district cooling include central Paris and the Marina Bay district in Singapore. Engie contributes to a district cooling project in Malaysia and is taking part in another project near Manila. Holleaux also said the company is interested in the upcoming $3.5 billion, 41-acre property development called One Bangkok, which plans to utilize district cooling.

To contact the reporter on this story: Abigail Wen Yi Ng in Singapore at ang329@bloomberg.net

To contact the editors responsible for this story: Stephanie Phang at sphang@bloomberg.net, Ramsey Al-Rikabi

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