The EU legislature has so far focused on the data-privacy and consumer-protection aspects of AI technologies. At the same time, AI is seen as a key driver of the green strategies of the EU. Yet, the EU regulatory and policy framework tends to neglect the environmental implications of AI. The massive employment of AI technologies results in a significant increase in energy consumption and affects the exploitation of rare natural resources dramatically. The Declaration on Digital Rights and Principles for the Digital Decade, the final chapter of which is dedicated to digital sustainability, is a first step in the attempt to plug this gap. The present article assesses the nature of the principles that have been proposed and traces their conceptual genealogy within the EU regulatory and policy framework. It identifies the emergence of a new principle of sustainable digital products and services, which is made explicit by the Declaration through a process of normative retrofitting.The article questions the ambitions behind this principle by reference to the oxymoron of the twin transitions, which pervades the current economic model of the EU and its sustainability targets, and to the emerging idea of digital sobriety.