With its digital strategy “Shaping Europe’s Digital Future”, the EU is decisively pursuing the goal of building an innovative data economy. The central building blocks of this strategy are interoperable data spaces, which are intended to enable the sovereign and trustworthy exchange of data across application sectors and national borders. However, despite explicitly formulated regulatory principles, it remains unclear how these can be made tangible in concrete implementation. This paper offers a conceptual contribution to the design of data spaces by examining the diverse perspectives involved and the value conflicts that arise between them. Drawing on our experience as designers in an EU energy data space project, we use the notion of trustworthiness as an entry point to explore these tensions: How can systems be designed in ways that meet users’ expectations of trust, while also aligning with ethical, legal, economic, technical, and political demands? To ground our reflection, we complement it with empirical insights from a survey (n = 24) and qualitative interviews with potential users. In our analysis, we follow basic principles of Green Technology and Digital Humanism. Rather than offering solutions, this paper aims to clarify the conceptual problem space and support critical reflection in future design and governance processes.