The importance of considering the environmental performance of buildings during conceptual stages of the design process is growing as a consequence of the restrictive requirements of building regulations and energy certification. The façade plays a key role in the design of buildings that need to meet strict requirements of energy efficiency and at the same time provide internal comfort conditions. For the work of this thesis, a simulation-optimisation tool was developed in Matlab environment to automate the coupling of the free energy simulation program EnergyPlus to the optimisation capabilities of the genetic algorithms included in Matlab‟s Optimisation Toolbox.