Architectural design greatly influences building energy performance (BEP), and energy-efficient design is therefore often studied. Architectural space layout also can affect BEP. However, only a few of the numerous studies on energy-efficient design considered the effect of space layout. Within these studies, the isolated effect of space layout on the BEP has hardly have been analysed systematically. The framework of Performative Computational Architecture (PCA) had been proven to be effective to improve BEP. PCA includes form generation, performance evaluation, and computational optimisation. With this framework, the building’s geometry and material properties are parametrised, and the performance is assessed for different combinations of design parameters. It aims to find the proper parameters that satisfy the defined objectives. This method can include the generation and assessment of space layouts. However, only a few studies have tried to combine the automatic generation of space layout with energy performance optimisation; nor the systematic analysis of the effects and relations between space layout and energy performance. Hence, the aim of this book is to investigate how space layout affects BEP, and to develop a computational method to support such investigation and the optimisation of space layout in order to improve BEP. The scope of this book is focussed on office buildings.