Heat and mass transport is modelled in a heterogeneous material where convection can take place in the continuous phase and diffusion can take place in both continuous and dispersed phase. The component being transported is in the continuous phase a vapour and in the dispersed phase a liquid. At the phase interface, the component can evaporate or condensate. Derivations are given for the effective material properties (diffusion coefficient and thermal conductivity) and for the transport of heat and mass.