Light levels, heavy temperatures
By Anushka Biswas, Cell and Molecular Biology, 2023
Close your eyes. Envision a dark and cloudy morning. You’re not quite sure what time of day it is, and no one touched the thermostat, but for some nearly inexplicable reason, you feel colder.
Nearly.
In September, the Ecole Polytechnique Fédérale de Lausanne (EPFL), a research institute specializing in natural sciences and engineering, developed a study shedding light on the influence of daylight levels in a room on perceived thermal comfort. It was found that there is a direct relationship between the level of surrounding environmental sunlight and how well participants in the study were able to tolerate heat.
[A study found] that there is a direct relationship between the level of surrounding environmental sunlight and how well participants in the study were able to tolerate heat.
Lead author Giorgia Chinazzo recruited 84 young men and women between the ages of 18 to 25 to fulfill a simple request: spend three hours in a room. Although the task was simple, the results harbored significant implications for the field of psychology. The rooms utilized for the study were one of three temperatures — 19°C, 23°C, or 27°C — and daylight levels — low, medium, or high. Color-neutral filters were also randomly positioned to regulate illuminance. After observing the measurements taken continuously of the participants’ body temperatures, the conclusions were astounding.
Results indicated that participants in the room set at 19°C felt more comfortable when the chamber was filled with light as opposed to minimal daylight. Unexpectedly, those situated in the 27°C room found themselves to feel cooler despite the room being flooded with daylight — not when light levels were at a low. Everyone’s body temperatures remained constant throughout the experiment but their ability to accurately perceive temperature had not.
What might be causing these distorted perceptions? Before entering the study, participants were unaware of the researchers’ intended purpose to preserve the sanctity of the results. The effect of daylight is purely psychological.
The effect of daylight is purely psychological.
A pre-existing thermal perception model attempts to explain this shining phenomenon. This model attests that perceived comfort is based on a set of ideal values. As the range of values begins to deviate from the ideal, people tend to report impressions of decreasing comfort. In Chinazzo’s study, when the amount of daylight present subconsciously contradicted the expected level of light associated with each level of temperature — whether it be too high or too low — the thermal perception and comfort factors of participants became distorted.
Moving forward, major businesses would benefit from carefully calculating light and temperature preferences to construct a comfortable, productive working environment. Until then, the next time you find it to be just a little too warm, close your eyes.
DOI: 10.1038/s41598–019–48963-y
