When Brian Janous started at Microsoft in 2011 as a data center utility architect, he joined at a time when energy and sustainability issues were still nascent.

“I was the first person that was brought into the organization to work on energy and sustainability issues. This was back in the time when it … certainly wasn’t clear to me why a company like Microsoft even needed someone like me,” Janous told CNBC by phone.

“And the person that was hiring me, (said), ‘I really think this whole cloud thing is going to be a big deal. And I think energy is going to be really important to the future of our company.’ And he was clearly correct. Obviously, over the last several years, as the cloud has really exploded, energy and our environmental footprints have become increasingly important issues,” he added.

The U.S. government estimated that data centers in the country used around 70 billion kWh of electricity in 2014, which equates to about 1.8% of the country’s total consumption, and the figure is set to reach approximately 73 billion kWh of energy in 2020.

Nine years after he joined Microsoft, Janous has risen to become the company’s general manager of energy and sustainability. Expanding its green ambitions to its supply chain meant the company went from having a “handful” of people overseeing sustainability to having teams think about environmental issues “as a core function,” Janous said. Efforts culminated in January, when Microsoft announced its goal to become carbon negative by 2030.

Last month, it also announced that it would replenish more water than it consumes by 2030, focusing on 40 “highly stressed” basins where it operates. It’s not the first tech company to make such an announcement — in May, Intel pledged to become net positive for water use by the end of the decade. And water use is a global issue: The U.N. estimates that the world is using six times more water now than it was 100 years ago and use is going up by about 1% annually. The U.S. government estimates that data centers would use 660 billion liters of water in 2020, that’s enough to fill 264,000 Olympic-sized swimming pools.

Microsoft now makes more than 36% of its revenue from its Commercial Cloud group — up from 10% in 2016 — and it’s working on ways to make the data centers (that provide those cloud computing products) more energy efficient, from putting them under water to testing hydrogen fuel cells for backup power. Azure, Microsoft’s public cloud network, is delivered via more than 60 data center regions, including one in Arizona — one of the driest states in the U.S. — that will open in 2021.

“We actually design our data centers to be incredibly water efficient. The vast majority of the time, even in places like Arizona, we use no water for cooling, we cool our data centers with outside air,” Janous explained. It’s only when temperatures reach about 85 degrees Farenheit that water has to be used, he added, and Microsoft uses evaporative cooling technology, which is similar to domestic air conditioning.

By: Lucy Handley @LUCYHANDLEY