Faced with the challenges presented by climate change, many interfaces presenting feedback on available, consumed or saved energy resources have been proposed to support a change of behavior towards a more environmental one in the field of sustainable HCI. If, for this purpose, bio-inspired systems have been proposed, few of them are presented in a tangible way or as histograms. This, despite encouraging results, as much in terms of awareness of energy consumption as in terms of emotional connection developed with the system, of artistic interfaces aiming at the commitment in an environmental behavior. With the aim of designing a system to support users in a shared practice of shifting energy demand, we present the results of the first steps of our approach. This paper focuses on design choice validation at an early stage of the design and development cycle, before spending time and money on physical prototyping; studying behavior change remains outside the scope of this work. Thus, the results presented concern the effectiveness and UX of static and animated mock-ups of eco-prediction and eco-feedback interfaces in the form of bio-inspired histograms. The results indicate that the efficacy of a bio-inspired histogram compared to a conventional histogram is lower. The second study shows that part of this loss of efficacy can be resolved by contextualizing the data. Also, without being significative, the leaf plant metaphor is found to be more effective and aesthetic than a metaphor closer to a classical histogram inspired by bamboo. We conclude that the leaf plant metaphor can be used for an eco-forecast and eco-feedback interface in the form of a histogram to shift the energy demand of battery-capable devices.CCS Concepts: • Human-centered computing → Empirical studies in HCI; Field studies; • Social and professional topics → Sustainability.