During the past months the city council of Genoa has started the construction of a school building provided with an active solar installation, and planned in collaboration with a specialized firm. To verify that the project choices were correct and to optimize plant controls, a mathematical model has been elaborated for a computer simulation of the plant operation. Thus it has been ascertained that dimensioning is correct and the integration of a heat pump is decidedly advantageous, even if during planning the latter did not appear quite convincing from an economic point of view.