IT provides vast benefits to organisations including providing online services to customers, helping optimise processes through big data analytics and helping employees do their jobs more effectively with SaaS tooling.

Unfortunately, these benefits come with a cost to the environment. The IT estates of most organisations comprise a lot of different device types from employee workstations to racks of servers. These are all energy-hungry and contribute to their overall carbon footprints. To put things in perspective, the current carbon emissions from the ICT sector worldwide are estimated at around 2% of global emissions which is comparable to the aviation industry.

There is consensus among climate scientists that in order to avoid the worst effects of climate change we must reduce carbon emissions to net zero by 2050. The term net zero means that emissions must be as low as possible and that anything remaining will be compensated for by removing carbon from the atmosphere. Organisations are increasingly making pledges in line with or in advance of the 2050 target. This includes Scott Logic which has signed up with the climate action group TechZero. Tackling the emissions resulting from the use of IT is a necessary part of meeting these goals.

As a software engineer with experience in cloud computing I wanted to look at how organisations can use the cloud to help reach net zero. Firstly a quick disclaimer: I’m not an expert in sustainability, but I’ve made an effort to provide sources for any claims and collated resources which you can use to start your own journey.

There are also many cloud providers out there but for the purposes of this post I’ve focused on the three which are probably the most well known: Amazon Web Services (AWS), Microsoft Azure and Google Cloud Platform.

Carbon benefits of migrating to the cloud

A report from 451 Research on AWS found that for the median surveyed EU enterprise moving from on-premises to the cloud can lower the carbon footprint of their workloads by 96%. Microsoft performed similar research and found that Azure data centres are 72-98% more carbon efficient than traditional enterprise data centres.

It’s worth noting that these reductions include the effects of carbon offsetting. This is used to compensate for the fact that there often isn’t enough energy from renewable sources near to data centres. Offsets are controversial and companies relying too heavily on them have sometimes been accused of “greenwashing” by purchasing them while continuing or expanding highly polluting activities.

To have credible offsets which make a positive impact cloud providers attempt use something called Purchase Power Agreements. A Purchase Power Agreement means that a supplier is contracted to provide a certain amount of renewable energy to the grid. This means new renewable energy projects get funded which would not have been otherwise been profitable to construct. Google is a leader in this regard, since 2018 for every kilowatt hour of energy its data centres used it has added back a kilowatt hour of renewable energy to the grid.

The benefit of this kind of offset is that over time you can reduce or eliminate the need for offsetting. Amazon, Google and Microsoft have all set targets of 2030 to use 100% renewable energy for their data centres. Amazon is currently five years ahead of this target and is projected to reach it by 2025.

Unfortunately, for a while your workload may still be at least partially powered by fossil fuels. To reduce the impact of this some cloud providers recommend choosing regions with the greenest energy mix. Even if your main workload needs to be run in a less than ideal region you might be able to run batch jobs in a cleaner region. Google provides a region picker which lets you optimise for carbon footprint as well as latency and price. Amazon also publishes details of its renewable projects worldwide so you can pick regions nearby. Microsoft has begun sharing this information with some customers under NDA but it’s not publicly available yet.

Luckily, it’s not just the use of renewables where cloud computing can reduce footprint in comparison with enterprise data centres. In fact the 451 Research report identified three key areas where carbon savings are made: more efficient and highly utilised servers (67% carbon reduction), more efficient data centre facilities (13% carbon reduction) and renewable energy usage (16% carbon reduction). As you can see the largest factors identified in the report are actually more efficient and highly utilised servers along with more efficient data centre facilities.

Higher efficiency makes sense since energy efficiency is a key factor in the profitability of cloud providers. As a result their hardware is often custom-built and more efficient. The use of bespoke chips such as Amazon’s Graviton processors which consume up to 60% less energy allows squeezing more compute out of every watt of power. Cloud providers can also save energy by being more efficient with cooling and using techniques such as evaporative cooling. Google even famously used artificial intelligence to reduce its cooling bill by 40%.

Server utilisation is also boosted in the cloud due to the benefits of elasticity. This means that customers can scale their compute resources to match demand using technologies such as auto scaling or serverless computing. Additionally, the size of VMs can be easily scaled to match the requirements of each workload. By using these techniques cloud providers can serve more customers from the same physical servers and reduce energy use. It’s worth noting that to take the best advantage of this you may need to re-architect your applications rather than just “lift-and-shift” them from on-premise data centres.

Optimising your workloads for sustainability

There are multiple resources available to help guide you in achieving reductions in energy use from your cloud workloads. For example, Amazon has integrated sustainability into its Well Architected Framework and Thoughtworks has shared a green cloud optimisation checklist. Amazon and Google have also shared best-practices through conference talks. In my next blog post I’ll be taking an in-depth look at these resources and sharing approaches and techniques for making your workloads more sustainable.

Whichever approach and techniques you use it’s essential to constantly measure emissions to gain insight into your current state and set goals for future improvements. All the three providers have tooling to help with this. Amazon and Google both have Carbon Footprint tools and Microsoft has a Sustainability Calculator.


Achieving net zero is an immense challenge but one with a lot of urgency. Ambitious targets have been set by both customers and providers. Due to efficiencies of scale, cloud providers can provide significant reductions in emissions compared with on premise data centres. This is especially true if workloads are architected and optimised to take advantage of the benefits of cloud computing.