The 9th Light Symposium, December 4-6, 2023 · Stockholm, Sweden Light Symposium 2023: Architecture Lighting Environments - Space With(Out) Light Daylight and electric light are an integral part of our built environment, and the sustainable design of lighting in this context, its presence, absence, and variability over time, requires research and practice that is both trans- and interdisciplinary.Although the presence of light is intimately linked to the life of humans, flora, and fauna, research and practice have not yet fully explored how light and dark can shape the built environment in a sustainable and holistic way.Research and practice into the affects and effects of light combine lighting design with other fields, including, for example, architecture, engineering, computer science, visualization, arts, humanities, social sciences, environmental psychology, health sciences, cognitive sciences, and more. The Light Symposium is an annual, international event to facilitate discussions and the exchanging of ideas; currently, it is coordinated by four academic partners; the Lighting Design Division at KTH in Sweden, Hochschule Wismar in Germany, AAU Copenhagen in Denmark, and SNU Kongsberg in Norway.The 9th Light Symposium, LS2023, was held in Stockholm from the 4th-6th of December 2023; it was hosted by the Architectural Lighting Design Division of KTH Royal Institute of Technology, in collaboration with the Perception Studio of Konstfack, the University of Arts, Crafts, and Design. During the 2,5 days of the symposium, more than 200 participants came together to share and learn about current research and design across different fields within architectural and urban lighting.In addition to invited keynote lectures, the conference program consisted of sessions with talks, panel discussions and poster presentations from researchers and practitioners worldwide, selected through a two-step peer-review process. The conference topics included daylight and electric light in architecture, art, and urban design, organized into four broad categories: Light and Health for all Species, Designing for Darkness, Sensory and Spatial Perceptions, Variability and Rhythmicity.These proceedings include 32 conference papers that were presented either as talks or posters during LS2023. All papers were reviewed by an international panel of reviewers. We thank all reviewers and our partner organizations for their time and help.We also thank the following organizations for their support of LS2023, and for enabling documentation through recordings and proceedings: The Swedish Energy Agency, Bertil & Britt Svenssons Stiftelse för Belysningsteknik, as well as Helvar, Selux, Fergin, Nordic LED, Stockholm Lighting, Annell, Fox Belysning, Optoga.The LS2023 Local Organizing Committee and Proceedings Editorial Team: Ute Besenecker, Foteini Kyriakidou, Gerhard Rehm, Hamidreza Eizadi, Federico Favero, Rodrigo Muro, Johanna Enger, Stavroula Angelaki, Seren DincelList of Reviewers are available in this Pdf.