Non-linear Relationships Between Daylight Illuminance, Individual User Characteristics, and Cognitive Performance in an Educational Interiors

Daylight is a critical factor in educational interiors, yet its impact on cognitive performance is often overlooked in favor of energy efficiency. This study investigates the relationship between daylight illuminance and cognitive performance within a university design studio, focusing on the non-linear interactions between seating positions as daylight illuminance level (K1–K4) and individual user characteristics. An experimental field study was conducted with undergraduate interior architecture students using the Raven Standard Progressive Matrices Test (RSPM) across five complexity levels (Sets A–E). Results indicate that cognitive performance is not a direct consequence of illuminance alone but emerges from complex interactions with gender, visual status, chronotype, and sleep duration. Findings challenge uniform lighting standards by revealing multiple optimal conditions; while higher illuminance improved performance for specific groups, moderate or lower levels were more favorable for others. The study highlights the necessity of shifting toward user-sensitive and spatially adaptive daylight strategies. By demonstrating the non-linear nature of environmental interaction, it contributes to design-oriented discussions aimed at enhancing both cognitive success and environmental satisfaction in learning environments.