Overall, Green IT, sustainable software or green software engineering and other
concepts of ICT for Sustainability are not standalone problems. Moreover, every
process of hardware and software development should involve aspects of Sustainable
Development. In this context, we answered the questions ‘‘What is a green, or rather a
sustainable software product?’’ ‘‘What are its criteria?’’ and ‘‘How can we develop
metrics for sustainable software and its engineering?’’ To address these questions, it
is necessary to provide additional tools and methods for software developers and for
everyone else who has a stake in software development and usage. Aspects of sustainable
development should be routinely addressed during the whole life cycle
of software products. Ideally, even customers should understand Green IT as a
‘‘must-have’’ requirement. Hence, it is necessary to reach a degree of standardization
in the field of energy-efficient software and its sustainable production.