Microsoft shared its data center power usage effectiveness (PUE) and water usage effectiveness (WUE) data for the first time, explaining that takeholders have made it clear that measuring energy and water consumption is crucial if Microsoft truly wants to "take sustainability into account for commercial decisions," Noelle Walsh, Microsoft's VP of cloud operations and innovation, wrote in a blog post.

Microsoft sets design goals for PUE and WUE, which are the cloud provider's theoretical estimates of the highest efficiency at which it can operate its data centers. This ensures accurate measurement of how efficient its data centers actually are, Walsh explained.

The cloud giant's efficiency targets vary based on a data center's age and usage. Data centers that are newer or are operating at peak utilization are more efficient, for example. Microsoft tracks efficiency data globally based on its three main operating regions: Americas; Asia Pacific; and Europe, Middle East, and Africa (EMEA).

PUE measures how efficient a data center is in terms of energy consumption. This includes the energy used to operate systems like power, cooling, and operating servers, data networks, and even lights.

A PUE of "1" represents highest possible efficiency. According to Walsh, Microsoft measures its PUE by dividing the total energy a facility needs by the total energy actually used for computing.

"We design and build our data centers toward the optimum PUE figure. We can also predict, with a high degree of accuracy, that optimum PUE figure. As we constantly innovate, we factor these changes into our data center designs to get as close to '1' as feasible," Walsh said.

Microsoft's global PUE design goal was 1.22, and it reported an actual global operating PUE of 1.18, meaning that Microsoft's global data center operations were more efficient than they were designed to be, she explained. The provider claims its newest generation of data centers have a design PUE of 1.12.

Microsoft's designed PUE for the Americas was also 1.22, and it reported an actual PUE of 1.17 for the region. The provider narrowly met its design goal of 1.2 in EMEA, reporting 1.185 PUE.

The Asia-Pacific region's designed PUE was 1.32, but Microsoft reported a higher actual PUE of 1.405 due to higher ambient temperatures in that region that require additional cooling and energy.

WUE is a similar metric to PUE in that it measures the efficiency and sustainability of data center operations. WUE is a key piece of Microsoft's strategy to be water positive by 2030, Walsh added.

The provider calculates WUE by dividing the liters (L) of water used for humidification and cooling by the total annual amount of power in kilowatt hours (kWh) needed to operate all its data center IT equipment.

Microsoft's global design goal for WUE was 0.39 L/kWh, but it reported an actual global WUE of 0.49 L/kWh. It also came close to meeting its design goal of 0.52 L/kWh for the Americas with an actual WUE of 0.55 L/kWh. In EMEA, Microsoft's design goal was 0.01 L/kWh with an actual WUE of 0.1 L/kWh.

The cloud giant has more room for improvement in the Asia-Pacific region — its design goal of 0.99 L/kWh was surpassed by the region's actual WUE of 1.65 L/kWh. Like with PUE, "Asia Pacific is higher due to higher ambient temperatures and as a result [of] the need in some places for water-cooled chillers," Walsh explained.

Data center location greatly impacts WUE. Humid locations have more atmospheric water available than arid locations, for example. And data centers in colder parts of the world, like Finland or Sweden, naturally require less cooling — and therefore less water. According to the Microsoft, its data centers are designed to minimize water use.

"We continue to integrate our standards in water reduction technologies," Walsh said of the provider's progress, citing its Arizona campus that uses direct outside air most of the year to cool its servers. Microsoft also employs direct evaporative cooling that uses less water than used by traditional water-based cooling techniques.

Microsoft's latest annual sustainability report shows it was able to reduce its scope 1 and scope 2 emissions by 17% year over year as a result of purchasing renewable energy. However, the provider also reported a 23% increase in its scope 3 emissions from the previous year.

The cloud giant attributed much of its scope 3 emissions jump to the global expansion of Microsoft’s data centers and growth in Xbox sales during the COVID-19 pandemic, Chief Environmental Officer Lucas Joppa wrote in the vendor’s 2021 Environmental Sustainability Report.

This category of emissions is often the most difficult for organizations to reduce because it includes all greenhouse gas emissions resulting from activities across the company's supply chain.

This means Microsoft is responsible for the carbon released from the electricity generated to power its devices and to produce the concrete and steel it uses in data center construction, the report explained.

According to Walsh, scope 3 emissions are hard to control and reduce "because we can often only influence change."

She stressed that Microsoft understands supply chain emissions reduction is a long-term effort. "This year we have increased our focus on operational discipline that is rooted in reliable data," she added.