Computing Profession

Linking IT’s Energy Consumption to Carbon Emissions

Corporate IT departments increasingly are trying to dial down their carbon emissions.

Whether it's a small business that sends a few dozen emails a day or a large Information Technology (IT) department at a Fortune 500 company that runs its digital hub 24/7, for the first time, there are general standards available to help them gauge the environmental impact of their IT operations. The set of 50 metrics and definitions is expected to help global enterprises  better understand and measure how the digital aspects of their businesses—like online meetings and cloud storage—impact the environment.

As we increasingly digitize how we work, live, and play,, which developed the "SustainableIT Environmental Standards 1.0," hopes that by issuing standards, companies that have not created their own sustainability systems will have a guidebook for reducing the environmental impact of the technologies they use. Rick Pastore, research principal at, a nonprofit organization dedicated to advancing global sustainability through technology leadership, says one of the goals is to bring to center stage the link between digital energy consumption and our carbon footprint. The impact of IT on the environment is enormous, he says. Take, for example, the energy required for the creation of a new algorithm: "The power to train one AI algorithm is like a 747 flying back from New York to London eight times," or nearly 16MT (metric tons) of CO2, says Pastore. "It's horrible."

"The continued rapid adoption of technology comes at an increasing cost to the environment and cannot go unchecked," says founding director Jedidiah Yueh. "These standards will help IT leaders contain the environmental cost of IT while using technology to drive more sustainable businesses and industries."

Since the SustainableIT guidelines were issued only in the last few months, it's too soon to measure their specific impact. But, Pastore expects that the guide will help companies that haven't yet launched their own sustainability systems understand and learn how to optimize energy consumption, helping them set sustainable development goals (SDGs) while influencing vendors— which increasingly are doing all the cloud hosting.

Global strategic technology firm Capgemini has been working for more than a decade to decrease its carbon footprint. After announcing its commitment publicly in 2021, Andrew Peterson, the company's environmental sustainability leader for the U.S. and a member of its Canada Corporate Social Responsibility team, says Capgemini migrated to a greener external cloud software service system, which allowed it to reduce the number of datacenters it uses from 45 to 18. "Anytime you're migrating systems from an on-premise data center into a more sophisticated cloud system, you're gonna see carbon reduction. So that was a very specific step that we took," Peterson says.

In addition, because its greatest area of energy usage is related to its IT estate, the work to decommission old IT equipment was "very significant," says Peterson. "Through that program, we were able to reduce our net electricity usage by 1.2 gigawatt hours."

Reducing E-Waste

According to the United Nations (UN) Environment Programme, only 20% of the worlds e-waste — such as old smartphones or computers — gets recycled; the rest goes into landfills. "We're going to make that 80% non-landfill," says Pastore, who explains that the new guidelines aim first to help companies quantify their environmental impact, and then to provide practical solutions for reducing that impact. Setting up partnerships with organizations that repurpose expired hardware is one specific way is spearheading change, says Pastore. The organization's latest sustainable IT guide offers ways to do this through IT Asset Disposal (ITAD) companies like HumanIT, which tracks and verifies what it does with donated hardware.

Peterson says the new guidebook will make it easier for companies to focus on IT sustainability "in a meaningful way and, frankly, in an impactful way. Sustainability within the corporate world has evolved differently for different organizations in different industries," says Peterson. While many companies have created comprehensive sustainability plans, Peterson's opinion is that those plans don't specifically address sustainable IT. "Only 18% or so of them actually are specifically addressing the carbon footprint of their IT estate," he says.

"The general hope is that the majority of CIOs in North America and Western Europe will feel a compelling motivation to step forward and get off the sidelines of sustainability … [and shift] into a proactive sustainability driving mode as fast as possible," says Pastore. In other words, do what Schneider Electric has done, suggests Pastore. The French multinational company reports 50% lower CO2 emissions from PCs and a 30% reduction in on-premise energy consumption through its Green IT Program.

Even before issued its standards, Rainer Karcher, who calls himself a "climate activist in a suit," was developing sustainable development goals for large corporations. He says until the standards were issued, one of the biggest problems was that the majority of corporations didn't know how to measure the environmental impact of any changes they made, and that meant they couldn't calculate where and what they needed to fix. Formerly with Siemens AG and now Head of Sustainability for multinational insurance and asset management firm Allianz Technology, Karcher has taken the system he created for the Germany-based technology company to his new job so Allianz can measure and better understand the impact of its operations on the environment. Karcher created what he calls "a sustainability data lake" to bring together 84 data sources, reducing the mostly manual effort of creating environmental, social, and corporate governance (ESG) reports by at least 50%. Karcher says Allianz, is now able to see that a third of its greenhouse gas emissions result from IT. "This shows already the big influence of what we have and why it is of importance to really do things differently," says Karcher.

One less email a day helps keep climate change away.

Sending an email comes with a "carbon cost," and that is an issue on which Karcher is focused. Because an email requires electricity to display, electricity to transfer it from one network to another, and electricity even during its temporary storage on a server, data from BBC Science Focus suggests that a single email without an attachment produces four to five grams of carbon emissions; that's equivalent to driving a car about a half a mile. If you "take the amount of employees at Allianz, which is 159,000, and if you know the amount of emails sent per employee per day, which is about 100, then you easily come up to a huge amount of carbon emissions," says Karcher.

"Imagine how much data we're using for this interview," Karcher says. "You are based in the U.S. on the East coast, I'm in Germany. Just imagine that the datacenter hosting our Zoom call is in Sydney. Our connection goes from the East Coast to Sydney back to Germany; all the way around. And there are plenty more network providers in between which are also being used, but you don't know that, and that's exactly where the whole issue of transparency comes in. The complexity of it is so high that people are quite afraid of measuring it, seeing the impact and finding a way to fix it."

Sustainability needs to become a part of the pervasive culture of IT, says Pastore. "The idea that you can create a digital operating model for your business but do sustainability separately is definitely short-sighted," said Pastore, adding that it is his belief this is how the majority of companies approach the issue. "Sustainability (particularly the environmental type) can't happen without digital; specifically, IT modernization and optimal digital operations," because the key to sustainability potential is data. "Data on power consumption, emissions, computing loads and capacity; personal data usage, privacy, and security; workforce and pipeline diversity numbers, etc.; all this data is needed to assess, track, report, and to inform sustainable decision-making. Without the CIO or CTO as a proactive player on the sustainability team, this data tapestry will have huge gaps and be too onerous to find and work with." 

Further, since not all enterprises currently have sustainability departments or one that focuses on the environmental impact of their IT, both Pastore and Karcher say providing standards is an important through line they believe will help companies reach sustainability goals. Transparency is key, as well. "If you take the example of cloud providers, AWS, Azure and Google, all of them are calculating the carbon footprint in different ways, and only one, Azure, is sharing how they do it; the others don't," says Karcher, who is a member of the board of The new standards issued by are open source and free to be shared.

"Having a strong set of standards through which to assess your own performance and then be able to demonstrate to the marketplace that you are taking meaningful action and not just paying lip service to a topic can be immensely valuable," says Peterson of the SustainabliltyIT Environmental Standards. "They're sort of a case for why it matters. Seems very strong to me, so I am actually quite excited to see where this goes in the industry."

SustainableIT Environmental Standards 1.0 is the first of three foundational tools in the toolbox. In the next few months, the organization plans to release two other pillars: social and governance standards, to drive sustainability progress and public awareness.

Pastore warns that now is the time for companies to get on the IT sustainability bandwagon because IT sustainability requirements will be coming down the pipeline. He points to the EU, which already has passed a Corporate Sustainability Reporting Directive (CSRD) to standardize corporate sustainability reporting. Here in the U.S., the Securities and Exchange Commission (SEC) has a set of rules it is expected to pass soon, too.


Cari Shane is a Washington, D.C.-based freelance journalist who writes on subjects she finds fascinating—especially science, medicine, and health. Her work can be found in a wide variety of publications from  Scientific American to Fast Company.

Join the Discussion (0)

Become a Member or Sign In to Post a Comment

The Latest from CACM

Shape the Future of Computing

ACM encourages its members to take a direct hand in shaping the future of the association. There are more ways than ever to get involved.

Get Involved

Communications of the ACM (CACM) is now a fully Open Access publication.

By opening CACM to the world, we hope to increase engagement among the broader computer science community and encourage non-members to discover the rich resources ACM has to offer.

Learn More