This research took an exploration into particular products which use human-power as main power source. Against the problem of over consumption of energy, it views the ‘human-powered product’ (HPP) not merely as an object that simply generates ‘free energy’; but instead considers as an interactive artefact that people can make sense of, and as a tool to practice energy saving behaviour. Efforts to improve the knowledge on design aspect of HPP and its statistical benefit have been proved, but largely by scientifically driven approaches. No such theoretical framework has been discussed or explored in relation to how people use HPP in their daily practice. Therefore, current research undertook the work into substantive area of HPP study that is understanding the actual ‘use-phase’. It explored how design can help induce a better use of HPP, and how intended behaviour of generating human-power can be reproduced, maintained, and internalised. An explorative investigation of actual HPP use was carried out through multiplecase studies, along with cross-disciplinary literature review which contributed in building an explanatory conceptual framework. The framework serves as guideline to explain, the abstract, prediction about phenomenon of HPP use; formulating questions to further study; and developing a ‘HPP Internalisation Model’ which hypothesised the suggestive design strategy for prolonging the HPP use. The hypotheoretical state of ‘HPP Internalisation Model’ was empirically iterated and final recommendations was integrated into a research artefact. Through final case study, this artefact was utilised to produce knowledge and understanding for constructing a theory. The result of study described the relationship, process, and influences between phenomena that account the explanatory concept for each dimensions of ‘HPP Internalisation Model’. As a final result, the model suggests a three dimensional (Empowerment, Feedback, and Motivation), and interdependent to each other, constituent elements in HPP design for bringing internalisation of human-power use. This research has therefore contributed to current knowledge by bringing the social-psychological theories and strategies of ‘design for sustainable behaviour’ together to develop the theoretical model of ‘HPP Internalisation Model’.