We have proposed the Totalized Hydrogen Energy Utilization System(THEUS) for applying to commercial buildings. THEUS consists of fuel cells, water electrolyzers, metal hydride tanks and their auxiliaries. We evaluated the energy saving of the basic THEUS in view of an actual operation using thermal demand data of actual buildings. The THEUS have ability for achieving energy saving, in comparison with an ice storage system for cooling demand. We have developed the hydrogen storage system using metal hydride and unitized reversible cell (URC) combine the functionality of a fuel cell and an electrolyzer in a single device, these are important components of THEUS. The metal hydride tank designed and manufactured to evaluate that we assumed actual operation in the experiments. We developed the numerical simulation code, and simulation results are in good agreement with experimental data. The simulation about two tanks system was done by using this code. The heat utilization can be improved greatly. To achieve URC commercial use, improvement of durability was examined. It confirmed that our URC had durability for several thousand hours.