The Conflict of Light: When regulations shift the sun Part 2 Dissertation 2025 Miguel Flores National University of Engineering | Peru Natural lighting in architecture is essential for human well-being and environmental sustainability, especially in high-density urban settings like Lima, Peru. This study examines changes in natural lighting regulations between 1969 and 2021, focusing on their impact on the quality of living spaces in multifamily buildings. The research question is: How have the regulatory requirements for natural lighting in multifamily housing changed in Lima between 1969 and 2021?Using a qualitative approach and a case study method, the research compares two buildings: the San Felipe Residential Complex (1969) and the YOU 502 (2021). Both are in Lima, offering similar urban and climatic conditions.The methodology includes the review of historical and current regulations, architectural plan analysis, daylight simulations, and evaluation of light wells and window openings. Findings reveal that the 1969 code promoted more generous natural light entry, while the 2021 regulations offer greater design flexibility but reduced lighting efficiency.The study highlights how regulatory frameworks shape spatial quality and energy sustainability. It recommends revising current norms to include performance-based lighting indicators and increasing minimum lighting surface percentages to improve liveability and promote sustainable urban housing. Tutor(s) Luis Espinoza Luis Soldevilla Jorge Zaldivar