Liquid Composite Moulding LCM processes are increasingly popular in the aerospace and related industries for the production of high quality composite parts. Filling simulations are often used in the design of moulds for LCM processes for efficient and complete filling of the mould. This paper proposes an energy balance equation for modelling energy interactions in a typical LCM process for implementation in Computational Fluid Dynamics (CFD) tools such as Open Field Operation and Manipulation (OpenFOAM). The derivation of the energy balance is first described in detail, followed by a brief description of an additional equation to be solved to find the degree of cure for simulations involving a chemically reactive resin. For a preliminary validation, a simplified version of the energy equation is implemented in OpenFOAM and simulation results are compared to experiments. The temperatures predicted by the simulations are seen to closely match the experimentally observed temperatures.