Sustainability in energy and buildings 2021 Chapter 1. Examining the Deviation in Energy Saving Estimations Due to the Use of the Degree Days Method Chapter 2. Impact of Climate Zone and Orientation Angle on the Recurring Massing School Typologies in Turkey Chapter 3. Analysis of the influence of aerodynamic Roughness on Urban Vertical Space form: an example of Shenzhen central area Chapter 4. Assessing the impact of lockdown due to COVID 19 on the electricity consumption of a housing development in the UK Chapter 5. Embodied energy and global warming potential of radon preventive measures applied in new family houses Chapter 6. Automatic Architectural Drawing Labelling using Deep Convolutional Neural Network Chapter 7. The response of the Italian healthcare facilities to the COVID 19 pandemic: analysis of national and regional legislation Chapter 8. Evaluation of Circular Construction Works During Design Phase: An Overview of Valuation Tools Chapter 9. Landscape Integrated Photovoltaic System for a Solar Island in the Venetian Lagoon Chapter 10. Leaving or sheltering A simulation based comparison of flood evacuation strategies in urban built environments Chapter 11. Numerical assessment of the impact of roof albedo and thermal resistance on urban overheating: A case study in southern Italy Chapter 12. The value of the colour temperature in a low light intensity design Chapter 13. A methodology for fast simulation of energy retrofitting scenarios of social building stock Chapter 14. Flood risk of Open Spaces: from microscale factors of Built Environment to risk reduction strategies Chapter 15. Low cost architectural strategies to reduce heat stress in social housing for hot desert climates. This book contains the proceedings of the 13th KES International Conference on Sustainability and Energy in Buildings 2021 (SEB2021) held in Split Croatia during 15–17 September 2021 organized by KES International. SEB21 invited contributions on a range of topics related to sustainable buildings and explored innovative themes regarding sustainable energy systems. The conference formed an exciting chance to present interact and learn about the latest research and practical developments on the subject. The conference attracted submissions from around the world. Submissions for the Full Paper Track were subjected to a blind peer review process. Only the best of these were selected for presentation at the conference and publication in these proceedings. It is intended that this book provides a useful and informative snapshot of recent research developments in the important and vibrant area of sustainability in energy and buildings. .