The present document shows a technical and economical study of viability, for a project which pretends to minimize the energetic consumption of a gym. For this purpose, a new building has been designed in order that it becomes the most self-sufficient possible by adapting it to the climate conditions of the zone. It has been designed on bioclimatic architectural basis. The building has also been provided with renewable energy sources in order to minimize dependence on external energy sources. Finally the present technical solutions available to generate electricity using the human effort are showed. And also the electricity that could be generated by these solutions in a gym, as the present one, has been quantified. Once all the energy saving measures has been considered we proceed to the calculations of the economical viability of the project. The final aim of the present Project, is therefore, to know the different available solutions to save energy on a building, quantify the possible energetic saving that can be obtained by these solutions on a gym, and to determine whether it is economically interesting to invest on a project like this one. The initial idea of this project was to determine whether the energy that could be generated through human physical exercise, would be sufficient to cover the energy necessities of common applications such as illumination or temperature regulation. But, it was considered interesting to widen the objectives of the project, by studying measures that could reduce in advance the energy required, increasing the specific weight of the energy generated by the users, in the final balance.