Designing healthier indoor lighting
Myrta Gkaintatzi Masouti defended her PhD thesis at the Department of Built Environment on December 11.
Light helps us see, but it also affects how we feel, sleep, and function. Daylight helps us regulate our internal body clock, keeping us alert during the day and helping us sleep at night. However, modern life often keeps us indoors, where we miss out on the benefits of daylight. For this reason, it is important to design indoor lighting that supports not just visibility, but also health and well-being.
For the design of indoor lighting, architects and lighting designers use digital tools to simulate how light is distributed in a room. But simulating light in a room is not enough. We need to think about how light reaches people's eyes throughout the day, because light at the eyes is what influences the internal body clock and alertness.
Improving lighting simulation tools
For her PhD research, explored ways to improve simulation tools used in building design so they could better support human health and well-being. She approached this challenge in two parts: first, by reviewing existing tools and developing a new simulation tool; and second, by studying how people鈥檚 viewing behavior鈥攕pecifically where they looked鈥攁ffected the light that reached their eyes.
In the first part, Gkaintatzi Masouti reviewed current research tools and identified several limitations. One major limitation was that these tools rarely accounted for how people moved and shifted their gaze. To understand how lighting professionals used these tools, she conducted an online survey.
The results showed that while designers used simulation tools, they seldom applied them to predict health-related effects of light. To address these gaps, she developed a new simulation tool that integrated all critical factors鈥攍ight鈥檚 amount, color, direction, and timing鈥攈elping designers compare options and researchers study light鈥檚 impact more accurately.
Does viewing behavior matter?
The second part of Gkaintatzi Masouti鈥檚 research focused on a key question: Did it matter how people looked around during the day when simulating the light they received? To find out, Gkaintatzi Masouti conducted two experiments: one with a single person in an office and another in a shared open-plan office.
In both experiments, two scenarios were compared: one assuming the person always looked straight at a computer screen, and another tracking natural head movements during work.
The experiments revealed that people spent most of their time looking at their screens, with head movements staying within a small range. Differences in light exposure between the two scenarios were limited, even though the tracked scenario showed more frequent changes throughout the day. These variations did not lead to major differences in predicted alertness. Therefore, assuming that a person looked straight ahead at their computer screen proved to be a reasonable simplification.
This PhD thesis reviews the current tools in lighting research and practice, introduces a new simulation tool, and shows that a simple assumption about where people look can still give useful results. It is a step towards creating environments with healthier indoor lighting.
Title of PhD thesis: The role of viewing behavior in simulating personal light conditions Supervisors: Ingrid Heynderickx, Mari毛lle Aarts and Juli毛tte van Duijnhoven.