Dr Marja-Liisa Siikonen is a wellknown and highly respected expert in the science of people flow. We first met in the late 1980s when she worked at Kone, and I worked at Arup. We have continued our conversation for over 30 years at conferences, working together on projects, and at standards meetings. I am proud to have her as a friend, even if we occasionally have technical disagreements!

In their book description, the publisher, Wiley Blacker, explains that People Flow in Buildings is perfect for software designers in the private sector and academia, appealing also to lift consultants, manufacturers, and architects. It is a valuable record of Marja-Liisa’s substantial research and experience. The book explains how modern trends in building usage have affected how people use buildings. It was written during the Covid-19 pandemic and acknowledges the unknowns of the “new normal”, which is a live discussion among practitioners in this area. The key topics covered are measurement, control, modelling, and planning. The book is divided into five parts as follows