The Devil Is in the Details When Assessing Data Center Sustainability

How green is a given data center, really? A new report by Cirrus Nexus found the answer can vary significantly based on factors like time of day or season. Here's what to consider when evaluating data center sustainability options.

Christopher Tozzi, Technology Analyst

March 23, 2023

4 Min Read
solar panels and wind turbines

In a simpler world, embracing data center sustainability would be as easy as selecting a green data center to host your workloads – meaning one that sources as much energy as possible from renewables – and calling it a day.

But in the real world, the extent to which a given data center is actually green can vary significantly based on factors like time of day and the season of the year. As a result, assessing data center sustainability requires nuanced and granular evaluation of energy sourcing patterns on a continuous basis. You can't look at average sustainability rates alone to gain accurate insight into how green a data center will actually be for your workloads.

That, at least, is one of the key takeaways from new research released by Cirrus Nexus, a company that specializes in monitoring cloud computing spending and carbon emissions. Keep reading for a summary of the report and what it means for businesses seeking to keep their data center strategy green.

Tracking Data Center Carbon Intensity

The report, titled "The Cleanest Data Center Regions," examined the carbon intensity of a typical workload (specifically, a standard Linux-based server coupled with a hard disk and a MySQL database) within different data centers operated by major public cloud providers.

Related:Sustainable Data Centers: Just How Green Is Your Cloud Migration?

Carbon intensity is a measure of how much carbon is released in order to supply power to a workload. As you'd expect, data centers that source energy from renewables, like wind and solar, have lower overall carbon intensity measurements than data centers that rely primarily on fossil fuels.

Yet what's interesting is that actual carbon intensity levels vary dramatically over the course of the day, as well as during different times of the year, according to Cirrus Nexus's data.

For example, data centers based in California experience low carbon intensity during the day, when it's typically sunny in the region and when solar power accounts for 39 percent of total data center energy sourcing, according to the report. But at night, solar panels go dark and carbon-intense energy sources like natural gas make up the difference, leading to significantly higher carbon intensity rates during nighttime.

Likewise, by comparing the findings of this report with an earlier study conducted in summer 2022, Cirrus Nexus found major seasonal variations in data center sustainability. Data centers based in the central United States were among the most carbon-intense last summer but experienced the lowest levels of carbon intensity of all U.S. data centers this past winter, thanks to increased availability of wind power in the colder months.

To Optimize Data Center Sustainability, Think Beyond Averages

The report's findings are important because they highlight the need to look at more than the average carbon intensity of various data center regions when evaluating data center sustainability options. Just because a given data center or data center location reports higher rates of clean energy sourcing in general doesn't mean it will actually deliver cleaner energy for your particular workloads on a regular basis.

Instead, factors like the time of day when your workloads are most active might dramatically impact how green the workloads are. For instance, workloads hosted in California might be relatively green if demand for them peaks during the day (when, again, they can be powered largely with solar energy). But if traffic peaks when it's dark in California, your workloads are probably dirtier (from an energy perspective) than the average sustainability data for your data center might suggest.

In a similar vein, the report highlights the value of moving workloads between data center regions in order to optimize for sustainability. The fact that some regions' data centers are greener during certain seasons than others could be a reason to migrate workloads over the course of a year in order to take advantage of varying availability of clean energy. Your applications might be greener if you host them in the Central U.S. during the winter, for instance, but move them to a sunnier locale in summer when daylight hours peak.

On balance, it's important to note that the Cirrus Nexus research looked only at the carbon intensity of one type of workload, and only at energy consumption data from data centers owned by major public clouds. Optimizing workloads to reduce energy consumption and exploring hosting options from data center providers other than the big public clouds might also help you reduce the carbon intensity of your workloads, regardless of the region where they are hosted.

Still, the Cirrus Nexus report highlights the central importance of looking beyond averages when evaluating data center sustainability. Think instead about the unique requirements and usage patterns of your workloads, then evaluate how well they align with the hour-by-hour and season-by-season energy sourcing practices of different data centers.

About the Author(s)

Christopher Tozzi

Technology Analyst, Fixate.IO

Christopher Tozzi is a technology analyst with subject matter expertise in cloud computing, application development, open source software, virtualization, containers and more. He also lectures at a major university in the Albany, New York, area. His book, “For Fun and Profit: A History of the Free and Open Source Software Revolution,” was published by MIT Press.

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