Local grids featuring multiple carriers (electricity, gas and district heating) have attracted a certain degree of attention in the last few years, since technologies and components for the efficient conversion and storage of energy in different forms are becoming increasingly available. Grids of this type interact through energy hubs, i.e. grid nodes featuring connections to multiple energy carriers. The present work proposes a unified framework for modelling and controlling such systems, including both the network infrastructure and the energy hubs, where in particular aspects relating to the former are highlighted and analysed. The approach is employed for the case-study of an Alpine village in Switzerland.