This paper analyzes a covered swimming pool in a sports centre in the middle of Italy. Buildings like these have the highest energy consumptions: in fact particular temperature and relative humidity conditions have to be maintained throughout the seasons. We have evaluated the building's covering and the electrical and thermal plants. Then we have simulated the swimming with software: this didn't abide by the present Italian regulation. Subsequently we have designed the renovation, by means of insulating panels for outside walls and ceilings, new windows and a thermal blanket for the two pools. These changes have led to a decrease of 40% in annual energy consumptions. Finally we have also designed a photovoltaic plant, a solar thermal plant and a cogeneration plant to satisfy the energetic request of the pool, saving the maximum quantity of energy. At the end we made an economical and environmental analysis of the proposed investment.