Green Coding Guide : Energy Awareness Across Software Development Practices

The energy footprint of software systems has become an increasingly important concern as digital infrastructure continues to scale. While early sustainability efforts in information and communication technology (ICT) focused primarily on hardware efficiency and data-center optimization, it is now widely acknowledged that software itself plays a decisive role in determining runtime energy consumption. Software design and implementation choices directly influence how intensively hardware resources such as CPU, memory, network interfaces, storage devices, and accelerators are utilized. These usage patterns, in turn, determine the energy footprint of software during execution. Even small inefficiencies at the code or design level can accumulate into substantial energy consumption when software is executed at scale. Modern software systems often operate continuously, serve large user populations, and rely on distributed architectures. In such contexts, green coding is not an isolated optimization task but a software quality concern that interacts with performance, reliability, scalability, and maintainability. This guide approaches green coding as an engineering discipline grounded in evidence and measurement, rather than intuition or isolated best practices. It is written for a mixed audience of industry practitioners and researchers and aims to bridge research insights with day-to-day software development practice.