Parametric optimization of daylight performance in living rooms of mass housing: A case study of TOKİ İstanbul Sütlüce project

The effective use of natural daylight in spaces is a fundamental design element that both reduces energy consumption and improves indoor comfort and user satisfaction. Adequate daylight access increases lighting quality while minimizing the need for artificial lighting. In mass housing projects, the impact of architectural form, window placement and block orientation decisions on daylight performance is important, and when considered in detail in the early stages of design, it has the potential to significantly increase both spatial quality and energy efficiency. When it comes to mass housing, the most common model in Turkey is TOKİ projects. TOKİ is preferred due to its low cost, fast implementation and repetitive typology. With this standardization, only the building efficiency and social housing goals are supported; window sizes and block layouts are often designed without considering different environmental conditions and orientations. This situation leads to insufficient daylight performance in interior spaces and cannot provide user comfort. This study addresses the natural daylight performance problems frequently encountered in mass housing projects and examines parametric optimization strategies to improve this performance through the example of TOKİ İstanbul Sütlüce Project D Block which is a critical assessment area overlooking the Golden Horn in İstanbul Sütlüce. In this study, in order to determine the design criteria for daylight in mass housing, first a comprehensive literature review was conducted and then the information was compiled and then current situation simulations were conducted in the hall volumes where the shading effect of the surrounding buildings was felt at the most critical level. Three optimization scenarios were developed by preserving the existing architectural form and window arrangement in the hall units of TOKİ İstanbul Sütlüce Project D Block. As the method of the study, an innovative BIM-based workflow was developed and the model transferred from Revit was prepared for Daylight Autonomy (DA₁₅₀) analysis with Ladybug in the Rhino–Grasshopper environment; Rotation, Transport and Rotation+Transport scenarios were solved parametrically with Galapagos. Only the hall volumes were taken as the analysis area and the simulation steps were shown with comparative tables between floors. As a result of the study, the average DA₁₅₀ in the current situation halls was found to be 59,7%, while in the optimization results, this value increased to 62.6% with the Rotation scenario, 59.8% with Transport, and 66.5% with Rotation and Transport. The most effective strategy, the Rotation and Movement combination, achieved an 11.4% improvement, increasing the daily daylight usage time of living rooms by approximately 41 minutes and resulting in a performance enhancement that requires approximately 250 hours less artificial lighting usage annually. The findings reveal that holistic optimization of layout and orientation decisions, beyond window metrics, most effectively enhances daylight performance and demonstrates that building orientation is 29 times more effective than location changes. These results show that significant improvements can be achieved even in existing buildings through layout and orientation optimization alone without requiring architectural intervention.