Digital technology already accounts for 4% of global CO₂ emissions, with an upward trajectory. Beyond the discourse, designing leaner software is a concrete gesture within every developer's reach — and often synonymous with better code.
Digital technology now accounts for approximately 4% of global greenhouse gas emissions — more than civil aviation. And unlike other sectors, this footprint is growing: the proliferation of devices, ubiquitous video streaming, massive deployment of generative AI and the race for data centers all contribute to exponential energy consumption. Green IT is not a topic reserved for CIOs or infrastructure teams — it directly concerns daily design and development choices.
Algorithmic sobriety first
The primary source of savings is neither infrastructure nor hardware — it's the algorithm. An unoptimized SQL query loading ten times more data than necessary, a loop recalculating on every iteration what could be cached, a 4 MB image served in a 200-pixel component: each of these examples multiplies CPU cycles, bytes transferred and energy dissipated. The KISS principle applied to performance becomes an ecological gesture. Adding an index on a frequently filtered column isn't just a good practice — it reduces server work for every query, for the entire lifetime of the application.
Caching is an underused lever. Caching the results of an expensive calculation or remote query means serving the same result without redoing the work. HTTP cache-control, Redis, client-side memoization: the tools exist. Resistance often comes from fear of inconsistency — which is managed through a thoughtful invalidation policy rather than abandoning caching altogether.
Media and network transfers
Assets typically represent 70 to 90% of a web page's weight. Adopting modern formats — WebP and AVIF for images,
WebM and AV1 for video — reduces weight by 30 to 50% without perceptible quality loss. The srcset attribute ensures
only the resolution adapted to the screen is served. Lazy loading avoids loading resources that are never seen. These
optimizations are as good for Core Web Vitals and SEO as they are for the planet.
Deferred loading of non-critical scripts, removing dead JavaScript (tree-shaking), Brotli compression rather than gzip: every KB saved is multiplied by the number of page views. On a high-traffic site, the cumulative impact is significant.
Infrastructure and hosting choices
The choice of data center has a direct impact. Major cloud providers publish their PUE (Power Usage Effectiveness) and renewable energy commitments. Google Cloud and AWS offer regions with high green energy supply. Deploying in the region closest to your users reduces latency and network transfers. Right-sizing instances — not over-provisioning — avoids paying and consuming energy for idle capacity.
Ecodesign as a discipline
Software ecodesign adds an environmental dimension to classical quality criteria. It is measured with tools like GreenFrame, Scaphandre or the EcoIndex extension. It is practiced by removing rarely used features rather than adding new ones, questioning the necessity of a dark pattern that lengthens the user journey, preferring a serverless architecture that only consumes what is executed over a server running 24/7 at 2% utilization. Digital sobriety is rarely a sacrifice — it's often cleaner, faster code that's cheaper to operate.
→ See also: The KISS principle · Technical debt · Web image formats