The purpose of this paper is to analyse the optimal three-dimensional form of buildings that minimise energy consumption due to solar irradiation. We use an evolutionary algorithm (hybrid CMA-ES/HDE algorithm) already applied to maximise solar energy utilisation (Kampf and Robinson, 2010), which uses a cumulative sky model approach for the computation of incident irradiation on the building envelope. Various families of possible building forms are investigated with this methodology to find the optimal building form, in two locations with radically different climatic conditions, showing the features that a building should posses in order to optimise its energy performance with respect to the solar irradiation. (C) 2015 Elsevier Ltd. All rights reserved.