Indoor lighting has become a more important aspect of modern office spaces, particularly in light-constrained environments like open-plan ones. People can spend 80-90% of their time indoors in large parts of the globe, especially in Nordic countries. Our circadian rhythms and hormones are affected by the light that surrounds us. This makes indoor lighting an important aspect of our well-being. There are many opinions on indoor lighting solutions, and if there is one, they differ widely. Louis Poulsen, a Danish lighting manufacturer, set out to investigate the effects of artificial lighting in Copenhagen’s own headquarters.

Louis Poulsen HQ & Showroom in Copenhagen, Denmark . Image © Martin Sølyst

The Louis Poulsen office is a historic building and therefore renovations were not possible due to its protected status. Artificial lighting was required to create a comfortable indoor environment. This experiment was conducted over a period of four months, from November 2019 through February 2020. It demonstrated how dynamic lighting works in practice, and not just theoretically.

BSF Law Offices, Hudson Yards in New York City . Image © Eric Laignel

Louis Poulsen tested different light intensities and color temperatures to determine how dynamic lighting and a kelvin-adjustable light system affected indoor work conditions. The kelvin adjustable general lighting was able to simulate natural daylight from morning until night, with a color temperature of 2,700 to 5,700K (Kelvin). Desk lamps with fixed CCs between 2700 K to 3000 K provided additional lighting.

BSF Law Offices, Hudson Yards in New York City. Image © Eric Laignel

Four different light sequences were created to test the system. Each one could be run for up to three weeks. The “Daylight Sequence 1” was designed to follow the natural intensity of daylight during the day. It started at 40% in the morning, and then increased to 100% by noon. The color temperature changed from totally hot (2700K), to cold (5700K), around 2pm. The second “Energizer” sequence was designed to test whether employees could feel more awakened and energized by small, high-intensity sequences. The third “Static Intensity” sequence used warm lighting throughout the morning and afternoon, and very cold lighting at noon. It maintained 100% intensity throughout the day. The last “Dynamic intensity” sequence maintained a color temperature at 4000 K and a shifting intensity of between 40% to 100%.

The experiment was based on employee feedback and showed that sequences in which both intensity and color temperature were changed fared better than other lighting options. Employees preferred color temperatures between 2700 and 4200 K, with maximum intensity of 80%. The sequence in which intensity was constant and only the color temperature changed received negative feedback. This included complaints about headaches and tired eyes.

INGENIØR’NE in Esbjerg, Denmark. Image © Jesper Ray

Employees also reported discomfort from high color temperatures exceeding 4200 K, and 2700K light intensities. The majority of employees who participated in the survey said that they used their desk lamps in the morning and late afternoon. Desk lamps are particularly important in environments that have limited lighting control. Individual desk lamps are especially useful in large offices where employees have little control over the lighting conditions.

INGENIØR’NE in Esbjerg, Denmark. Image © Jesper Ray

The experiment was not designed to reach a scientific conclusion. It simply attempted to bring theory to life and create a dialogue about dynamic lighting. The study’s results strongly suggest that dynamic lighting can create a more productive working environment for office workers, despite the complexity of the subject. A better understanding of dynamic lighting can help to reduce many of the lighting problems that are faced in open-plan offices today.