The 2025 Cloud Sustainability Top 10: Rethinking green in a multicloud world
Introducing our new and improved research
In 2025, Computing has reimagined our cloud sustainability research model based on your feedback.
Every spring, Computing publishes its definitive ranking of cloud providers based on how sustainably they operate. For several years, our in-depth assessment has served as a benchmark for environmental responsibility in cloud computing. We’ve consistently refined our methodology to reflect the evolving sustainability landscape—and this year, we’ve changed it up.
In 2024, Google Cloud Platform won the “Green Cloud” title, followed closely by Microsoft Azure and Amazon Web Services. But this year, after thoughtful feedback from our subscribers and industry experts, we’ve reimagined our research model to reflect the more flexible and creative ways you’ve told us you’re using cloud services.
Changed framework
At the heart of our new approach is a more focused sustainability quadrant. We continue to evaluate cloud providers across four essential pillars which you can see set out below:
Each provider can score up to 50 points. But rather than overwhelming readers with metrics and detail, we’ve cut each category down to just two or three of the most critical, measurable data points.
Why?
For a quick explainer see the video below:
Firstly, sustainability goals have become increasingly homogeneous across Big Cloud. The differences tend to come down to implementation, rather than ambition. Secondly, narrowing our criteria allows us to focus on the most critical metrics: carbon emissions, renewable energy usage, water consumption, waste management, and how transparently providers report their progress.
This leaner model has the benefit of allowing us to analyse a broader range of providers. Today’s cloud ecosystem is diverse, with hybrid and multicloud architectures the norm. Our previous focus on Big Cloud didn’t properly reflect how companies are using it.
That’s why this year’s list includes not just hyperscale giants like AWS and Azure, but also platforms such as Salesforce, Oracle’s OCI, Lenovo TruScale, OVHCloud, IONOS Group, and UpCloud.
The inclusion of European providers also speaks to growing concerns over data sovereignty and geopolitical uncertainty, particularly for UK and EU-based organisations evaluating US-owned clouds.
Let’s be real—most organisations don’t choose cloud platforms based solely on sustainability. Cost, performance and purpose drive most purchasing decisions. Of course they do. But the environmental impact of cloud computing is no longer an afterthought. It isn't at the top of the list – but it is on the list, especially as the rise of power-hungry technologies like generative AI increases the energy footprint of datacentres.
This research is intended to inform purchasing decisions when sustainability is part of the decision-making calculus by separating greenwashing from genuine progress and giving credit where it’s due.
Our ongoing series will dive deeper into specific comparisons, verticals, and categories—highlighting where cloud providers shine, and where they still fall short. For now, read on for our Top 10 Most Sustainable Cloud Providers of 2025.
UpCloud
It was difficult to assess UpCloud in any meaningful way as very minimal data is publicly available. The company has an ESG page rather than a full report. Consequently, UpCloud scored 10 points out of 50.
In renewable energy for example, UpCloud states that 70% of its datacentres run on renewable energy and 100% of offices do likewise. However, no details are provided about the form this renewable energy takes. Does UpCloud generate its own energy? Does it sign direct agreements with utility providers? Does it purchase Renewable Energy Credits? (RECs.) We just don’t know. Of course, we asked and an UpCloud spokesperson said:
“We have recently started our ESG program, and in the midst of fully establishing the program. Currently, we are unable to provide you with the full extent of data requested. We would be happy to take part in future research.”
Oracle OCI
Oracle scored 18 points. It is one of the stronger clouds in terms of how the company manages its indirect impact with clear policy for suppliers and a raft of tools available for customers to monitor and manage carbon.
However, the company’s emissions are growing, and very limited data is available on how renewable energy is used to offset scope 2 carbon emissions. There is no meaningful target to reduce water consumption, and the only type of waste reported in electronic waste. The company scores poorly for transparency. Information is hard to find and incomplete.
Computing invited Oracle to fill in some gaps in our analysis but Oracle did not respond.
Salesforce
Salesforce scores 21 points in total. Like Oracle, Salesforce scored highly in the indirect quadrant, with a carbon footprint tool for customers which seems to be able to measure all scopes of carbon emission associated with their use of Salesforce. The company has a target for 60% of its supplier to set a science-based target for carbon emission reductions.
Salesforce has also put serious thought into what meaningful renewable energy purchases look like.
However, emissions are heading in wrong direction (which Salesforce acknowledges in its own reporting) and 35% of the water consumed by the company is taken from areas of high or very high-water stress. No data about waste is provided.
Computing invited Salesforce to fill in some gaps in our analysis but Salesforce did not respond.
Microsoft Azure
A few years ago, Microsoft came top of our sustainability rankings but has steadily lost ground. This year the company scored 23 points.
As a company Microsoft uses its power admirably, and scores highly in the indirect impact part of the analysis having expanded functionality across its sustainability manager tools to enable customers to better manage their impact. Microsoft is also working to get a much clearer understanding – and reduction – of emissions from shipping, trucking and aviation. It’s also examining semiconductor emissions more closely.
However, carbon emissions are climbing. Microsoft urges readers of its reporting to look at longer terms trends rather than year-on-year change and claims that the company’s Scope 1 and 2 emissions have reduced since 2020. This just isn’t the case. Scope 1 emissions increased from 118,100mtCO2e to 144,960mtCO2e since 2020. Scope 2 (location-based emissions) have almost doubled from 4,328,916mtCO2e to more than 8 million mtCO2e. The company claims to want to halve scope 3 emissions by 2030 but at present they are still increasing.
Water consumption increased as did the volume of waste generated and the volume sent to landfill.
Microsoft does however pick up almost maximum points for the transparency of its carbon accounting.
Computing invited Microsoft to fill in some gaps in our analysis but Microsoft did not respond.
Amazon AWS
AWS has gradually worked its way up the mid table of cloud sustainability by virtue of very slowly providing more data each year, this year scoring 24 points. In contrast to the usual claims of greenwashing, AWS is more likely to indulge in greenhushing. The giant has really innovated in crucial areas and looks to be making progress in waste and circular economy in particular.
For example, the average life of servers in datacentres has been increased from five to six years, and the company has pioneered the use of steel from electric arc furnaces and uses recycled plastic in its datacentres which has a smaller carbon footprint than equivalent virgin product. But the reluctance of Amazon to provide data to quantify achievements means it often ends up underscoring.
AWS presents a story of slightly reduced carbon emissions despite strong company growth. As ever, this is part truth, part presentation. Scope 3 location-based carbon emissions (data which is found only in the appendix of the letter of assurance accompanying the ESG report) decreased in FY23, but the problem is that this reduction was more than offset by the growth in scope 1 and 2 emissions.
AWS present this, perfectly legitimately, as a decrease because scope 2 emissions are offset against their renewable energy projects which now total more than 500 globally. But this presentation does not reflect the carbon put into the air by Amazon operations. Amazon reports within carbon disclosure rules. But whether corporates should be allowed to “offset" the emissions generated in one country with renewable energy that will be generated in a different country in two or three years-time, is, at best, debatable.
Computing invited AWS to fill in some gaps in our analysis but AWS did not respond.
Lenovo
Lenovo is primarily known for hardware but features in our analysis because of its Truscale IaaS hybrid cloud model. The company has a similar footprint to IBM and scores a strong average across all areas of the analysis, totaling 27 points in total.
Points of note include Lenovo publishing a bracing Scope 3 GHG emissions reduction target from procured goods and services of 66.5% per million US$ gross profit from base year 2018/19 by 29/30. This is going to put a great deal of pressure on Lenovo suppliers but it’s an example of a large company using its power for good.
What is less constructive is the fact the despite Lenovo offsetting more than 90% of their scope 2 emissions there is minimal transparency of the offsets used. Onsite solar generation increased by 48% in the last reporting year, but there is no explanation of the carbon accounting other than a statement that Lenovo purchases both RECs and REGOs, the shortcomings of which as a driver of additionality when it comes to renewable energy are well documented.
The company was criticised by Greenpeace in 2022 for using unbundled RECs for 97% of its reported renewable energy.
Computing invited Lenovo to fill in some gaps in our analysis but Lenovo did not respond.
IBM
Big Blue has worked hard to reduce the impact of its operation. It scores similarly to AWS and Microsoft and Lenovo with 28 points, but our analysis isn’t reflective of the fact that IBM produces a fraction of the emissions of Big Cloud, probably because IBM has far fewer datacentres.
IBM set a goal a decade ago to reduce GHG emissions by 68.5% by 2025 from base year of 2010. That target was met two years early in FY23. Carbon emissions also reduced year-on-year across all scopes. The only thing IBM lost points on here was the fact that the company only reports five out of the 15 categories of scope 3 emissions. Nonetheless emissions overall totalled approximately 813,000 mtCO2e. When you consider the fact that Amazon and Microsoft measure their emissions in millions of tonnes, IBM looks like a much lower carbon option.
74% of electricity consumed in datacentres comes from renewable sources and IBM scores highly here. What lets the company down is the lack of water data.
Computing invited IBM to fill in some gaps in our analysis but IBM did not respond.
Google GCP
Google makes the top 3, scoring 29 points, mainly by virtue of its excellent waste and circular economy reporting, and high level of transparency. A highlight in this area includes the proportion of Google’s cloud estate that consists of recycled or refurbished hardware increasing from 21 to 29%.
When it comes to transparency, Google does not attempt to sugar coat the fact that carbon emissions have risen by approximately 2 million mtCO2e across all scopes.
However, Google provides a reasonably convincing explanation that the increase is partly due to the fact that company matches its clean energy purchasing globally but reports emissions locally. This is fundamentally the difference between market and location-based emissions reporting.
Google also prioritises purchasing physical electricity along with associated “bundled” EACs. This drives additionality. Google says:
"While our approach to date has resulted in a discrepancy between our Scope 2 emissions trend and our 100% renewable energy match, we believe our shift in focus to 24/7 CFE procurement—matching our consumption on an hourly basis from within the same grid—will have a more significant impact on grid decarbonization and the clean energy transition. Our pursuit of 24/7 CFE remains one of our primary approaches to reducing our Scope 2 emissions."
Computing invited Google to fill in some gaps in our analysis but Google did not respond.
IONOS Group
In the runners up position in our analysis is IONOS Group, which scores an impressive 30 points.
Germany-based IONOS Group includes ten brands, including IONOS itself, offering an array of services for differently sized customers. The indirect impact of the company proved difficult to measure, particularly in terms of downstream emissions. Upstream emissions are covered by a target to have 90% of datacentre suppliers by spend committing to climate targets. However, the supplier code of conduct is all very voluntary although the company was happy to share that it uses to dedicated platform to collect supplier data.
The company only reports on market-based emissions but supplied location-based totals on request. Location-based scope 2 emissions were low at approximately 39,500 mtCO2e. The company argues, fairly, that because datacentres are powered by 100% renewable energy, market-based totals are fairer. Given that this renewable energy is either self-generated or sourced directly from utility suppliers we would agree.
Furthermore, IONOS told Computing that it did not use any carbon offsets. This is genuine renewable energy and honest carbon accounting.
IONOS group also supplied its water data on request. A spokesperson said:
“Our data centres' total water consumption in 2024 was 265.464,56 litres. It's worth noting that the majority of this usage (98.8%) came from the last one of our data centres to still be using water-based cooling during the first months of 2024. We're pleased to report that, as of now, all our data centres have transitioned to alternative cooling methods and no longer use water-based cooling."
OVHCloud
Top of the Computing cloud sustainability ranking is the French cloud company OVHCloud. The margin of victory is significant – OVHCloud scored 36 points in total and stands well clear of IONOS Group.
OVHCloud has sustainability built into its model, which is why it scores so highly in the indirect impact quadrant. The methodology behind its carbon caculator for customers took eight months in development. The methodology brings in networking and cooling equipment as well as manufacturing, freight, end-of-life and waste calculations.
In terms of upstream impact, because OVHCloud builds its own datacentres in existing industrial facilities and produces its own racks and servers it is able to standardise component assembly which reduces waste – and indeed cost. Accurately tracking upstream emissions is easier when you’re the manufacturer.
Carbon emissions grew slightly, but the numbers are so small relative to the competition that OVHCloud only lost a couple of marks in this area. OVHCloud also uses much less water than its nearest competitors – only 125.7ML. For comparison, IONOS provided a figure of approximately 265ML and Google a mighty 24,000ML.
Waste and circular economy is also a strength with 27% of components and equipment coming from refurbished inventory and only 846 tonnes of waste produced.
The only real criticism of OVHCloud lies in its carbon accounting. The company has signed PPA agreements with solar supplier in France and Germany which is a constructive way of meeting its 100% renewable energy target. However, when Computing reached out to OVHCloud for more detail on how they apply these renewables in their accounting we received the following explanation:
“We have applied PPA in France and Germany. These PPA started delivering on January 1st 2025. The effect of those PPA are not yet accounted for : public report will appear in the Group next URD, end of 2025.
“We purchase and use Energy Attributes Certificates : GOs in France, Germany, Poland, REGOs in UK, CER in Canada, RECs in the USA. These EACs help us accounting carbon emission in market-based.”
Ideally, OVHCloud should phase the use of EACs out over time.