The natural light it is one of the most important elements in architectural practice. Beyond its basic function of illuminating spaces, sunlight has a profound influence on human health and well-being — regulating the circadian rhythm, affecting mood and productivity, and contributing to an overall sense of comfort. In the context of neuroarchitecture, a discipline that bridges the fields of architecture and neuroscience — the importance of natural light becomes even more evident, being recognised as one of the fundamental pillars for creating healthy and stimulating environments.
The impact of shadows: the case of New York City
A clear example of this concern is New York City, where the construction of skyscrapers along the so-called “Billionaires’ Row” — at the southern edge of Central Park — has sparked intense debates for years about the impact of the shadows cast by these buildings. Studies conducted by The New York Times mapped the shadows of the skyscrapers and revealed how they can stretch over a kilometer, casting significant shade (for several hours a day) over public spaces. This situation has raised concerns not only regarding urban aesthetics, but also about the impact on biodiversity, the microclimate, and, above all, the well-being of the people who use those spaces (New York Times, 2016).
These debates have led the city to consider stricter regulations regarding building height and urban integration, aiming to mitigate the adverse effects of prolonged shadows. This concern highlights how natural light, even in a highly densified urban environment, remains an essential resource that must be preserved and optimised.
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Natural light and mental health
The relationship between natural light and mental health is well documented in various studies. Adequate exposure to sunlight regulates the production of melatonin and serotonin — hormones that directly influence sleep cycles and emotional states. Well-lit environments naturally support concentration, productivity, and an overall sense of well-being. On the other hand, a lack of exposure to natural light is associated with disorders such as Seasonal Affective Disorder (SAD) and other mental health issues.
No contexto de escritórios e espaços de trabalho, estudos indicam que trabalhadores expostos à luz natural reportam maior satisfação e menor fadiga ocular, para além de apresentarem menores taxas de absentismo. Da mesma forma, nas escolas, a luz natural melhora o desempenho académico, enquanto que nos hospitais contribui para uma recuperação mais rápida dos pacientes.
Urban planning and the challenge of densification
In Portugal, the debate on urban densification often focuses on maximising land use and the verticalization of cities. While these strategies are crucial for addressing population growth and housing needs, it is important that they are accompanied by a deep reflection on the impacts on the quality of both public and private spaces, particularly regarding natural light.
The Plano Director Municipal (PDM)
The PDM (Plano Director Municipal) is the main territorial management tool at the municipal level and is outlined in the Política de Ordenamento do Território e de Urbanismo (Lei No. 31/2014, of May 30). It guides urban development, defining, among other aspects, parameters such as building density, maximum building height, setbacks, and also environmental criteria — which in some cases include concerns with solar exposure and ventilation.
Although there is no mandatory national standard that exclusively addresses natural light in all PDMs many municipalities incorporate requirements related to solar orientation, volumetry, and setbacks to ensure adequate natural lighting,especially in newly developed urban areas.
The PDMs are available at Sistema Nacional de Informação Territorial (SNIT)through the website Direção-Geral do Território (DGT)which centralizes information about territorial planning in Portugal. Each municipality also usually makes its PDM available on the official websites of the local city council.
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Neuroarchitecture for people
As architects, urban planners, and policymakers, we have the ethical responsibility to place human well-being at the heart of the design and planning process. Natural light should be seen not as a luxury, but as a right and a vital resource that shapes our physical and mental health. Designing with light involves understanding technical aspects, such as the orientation and sizing of openings, as well as the broader impacts of our decisions on the urban fabric and on people's daily lives.
Thus, neuroarchitecture reminds us that, ultimately, good design is design for people. And there is no truly human architecture without natural light.