This deliverable presents the outcomes of Task T1.1, Multi-Actor and Knowledge Centres Co-Design and Requirements Definition, within Work Package 1 (WP1) of the All Data for Green Deal (AD4GD) project. It builds upon the foundations laid in Deliverable 1.1 and documents the iterative process of refining user requirements for the Green Deal Data Space (GDDS). A central element of this process was the Co-Design Workshop, held in September 2023, which brought together project partners and stakeholders to collaboratively define user needs for two pilot applications—Lake Splashboard and BioConnect—as well as the broader General User Interface of the GDDS. Through participatory design methods, user journeys were created, initial prototypes were developed and user stories extracted. These prototypes were subsequently evaluated by potential end users, leading to the identification of additional user needs and refinement of existing user stories. As a result of this iterative process, a total of 115 user requirements were formulated, 30 requirements for Pilot 1, 49 requirements for Pilot 2 and 34 requirements for the General User Interface of the GDDS. This deliverable concludes the requirements definition phase, providing structured foundation for the implementation of the GDDS tools. The methodology applied, based on Human-Centered Design (HCD) principles, ensures that user needs remain central throughout the development process.