Abstract: A typical curtain wall façade of an office building is modelled and studied in order to find the configuration of selected parameters that minimizes the total carbon emissions arising from building operation. Simulation based optimisation techniques, namely a PSO algorithm coupled to a dynamic energy simulation engine, are used to perform a fully automated search aimed at finding the optimal values of the envelope features. The application is significant since the energy efficiency and comfort conditions of highly glazed buildings strongly depend on envelope design. Results of the optimisation are presented and discussed for four different orientations of the façade, highlighting the potential savings in comparison to a standard façade construction. The performance of the algorithm in generating satisfactory results is examined, and a way to find additional near optimal solutions to provide diversity is suggested. Finally the impact of different types of external shading devices and different climates is also investigated. [Copyright &y& Elsevier]