The aim of this paper is the modelling of a smart polygeneration grid and the development of its Energy Management System (EMS) for real-time optimal operations, minimizing variable costs. The proposed grid includes two different demands: water and cooling energy. While water can be obtained from the aqueduct or from an Atmospheric Water Generator system (AWG), cooling energy can be produced from a devoted cooler or from the chilled air of the AWG. The integration with renewable sources in the form of photovoltaic panels is also proposed. Moreover, the grid includes a water tank and a thermal storage system to have additional management flexibility and to avoid money losses in case of extra-productions. While the optimized management is common in electrical energy smart grids, the application of EMS tools in such polygenerative grids including water generation is quite rare. Following the development and validation of component models, attention is focused on the EMS details and its application aspects. To assess the EMS performance, the results obtained with the application of this new tool have been compared with a simple traditional management, showing the obtained economic and environmental benefits.