What is Green Software Engineering?

Shortly after becoming the 2021 Fuller Fellow, I began thinking about what I could learn (potentially abroad) and implement (locally) that would help me grow as a web developer, while also contributing to Fuller’s For Good initiative.

I soon came across Green Software Engineering (GSE), an emerging discipline that combines climate science with software and hardware best practices. I reached out to Asim Hussain, Green Cloud Advocacy Lead at Microsoft, who was kind enough to take some time out of his schedule to point me in the right direction: the Green Software Foundation (GSF) and its Principles of Green Software Engineering.

From Asim, I learnt more about the problem GSE is trying to solve, the leaders in the space, and how we, as developers and agencies, can use it in our day-to-day work. Here’s what I found.

Why it matters

The internet can feel weightless, but every page view is served by physical hardware that needs electricity. Here in Australia, data centres currently use around 4% of the country’s electricity, a share projected to reach 12% by 2030.* Globally, the information and communications technology (ICT) industry accounts for around 4% of greenhouse gas emissions, more than commercial flights at about 2.4%.† Software that demands ever more powerful devices also pushes people to replace hardware that still works, adding to electronic waste.

The largest players are already acting. Amazon is now the biggest corporate buyer of renewable energy and aims to run entirely on renewables by 2025.‡ Google has been carbon neutral since 2007.§ And Stripe, Alphabet, Meta, Shopify and McKinsey have launched Frontier, a commitment to buy $925M of permanent carbon removal by 2030.

The principles

The GSF groups the discipline into six areas:

• Carbon efficiency: emit the least amount of carbon possible.
• Energy efficiency: use the least amount of energy possible.
• Carbon awareness: do more when the electricity is cleaner, and less when it’s dirtier.
• Hardware efficiency: use the least amount of embodied carbon possible, so devices last longer.
• Measurement: what you can’t measure, you can’t improve.
• Climate commitments: understand exactly how a carbon reduction is achieved.

What we can do

The most effective option is green web development. Much of it overlaps with what already makes a site fast: smaller images, efficient code, good caching and not storing data you don’t need. Design plays a part too, from questioning autoplaying video and heavy font files to darker colour schemes, which use less power on OLED screens.

If reworking a site isn’t feasible right now, look at your hosting. Tools like the Website Carbon Calculator and Ecograder show where and how a site is hosted. From there, ask your host whether they use renewable energy, either directly or through power purchase agreements, and what environmental policies and certifications they hold. We did exactly that with our host - they took the request on board, completed a greenhouse gas inventory with Brisbane company Carbonhalo, and have committed to offsetting 59.24 tonnes of CO2e and becoming a Measured Carbon Neutral business. All because we asked.

Where neither is possible, at least in the short term, carbon offsetting can cover the emissions that are hard to avoid. It’s no replacement for using renewable energy directly, but it’s a step in the right direction.

Green software engineering won’t fix the internet’s footprint on its own, but it gives developers and agencies a practical way to start. Every bit counts.

Addendum, October 2026

This article was written in 2022 and has been left as it was. Some of the figures in it have since changed or been revised.

* The Australian Energy Market Operator estimates data centres used around 2.2% of the electricity supplied through the National Electricity Market in the 2024–25 financial year, and forecasts that to reach around 6% by 2029–30.

† Estimates of ICT’s share of global emissions vary widely. A 2021 study in the journal Patterns put it at 2.1–3.9%, so 4% is at the high end. Aviation accounts for roughly 2.5% of global CO2 emissions.

‡ Amazon says it matched all of the electricity consumed across its global operations with renewable energy in 2023, seven years ahead of its original 2030 target.

§ From 2023, Google stopped maintaining operational carbon neutrality, which it had achieved by buying carbon offsets. It’s now aiming for net-zero emissions across its operations and value chain by 2030.

The biggest change since 2022 has been the rise of generative AI. Training and running large AI models takes a great deal of computing power, and has driven a new wave of data centre construction. The International Energy Agency estimates data centres used around 415 TWh of electricity in 2024, about 1.5% of global consumption, and expects that to roughly double by 2030, with AI the biggest driver. It’s already showing up in company reporting: Google’s emissions rose 48% between 2019 and 2023, driven mainly by its data centres’ energy use and its supply chain. The principles above, particularly carbon awareness and measurement, matter more now than when this article was written.

On the standards side, the GSF’s Software Carbon Intensity specification has become an international standard (ISO/IEC 21031:2024), and the W3C is developing Web Sustainability Guidelines for designing and building lower-impact websites.