Sisley is an open software that uses the volume element method to model two-dimensional heat transfer problems under transient and steady-state conditions. It includes a powerful simulation engine coupled with a simple and interactive interface. It make it possible to generate dynamic equations of both physical and reduced models. This software is used to model conventional thermal bridges, as well as windows frames heat losses or specific walls (heated floor) and foundation. In this article we present Sisley software trough a thermal bridge application.