Let there be light

It boosts performance, brightens the mood, and even has healing powers – in correct doses, daylight is astonishingly good for humans. Experts from a wide range of fields are lighting up the darkness and building on nature as they do so.

Daylight can save lives – this is the conclusion of researchers who observed female patients in the intensive care unit of a hospital in Alberta, Canada. Those who were in a sun-drenched room survived a heart attack much more often than their fellow patients in dark rooms – and they also recovered more quickly. Admittedly, this is just one piece of the jigsaw, but the know­ledge assembled over time does, bit by bit, form a consistent picture – which is that natural light has a positive effect on health and well-being.

Figueiro observes the positive effects of daylight in environments where most confounding factors are controllable, such as hospitals or retirement homes. This is much more complicated in an office environment, yet she is seeing positive results even there. “Our studies show that office workers who receive a higher amount of daylight have better sleep, and lower levels of depression and stress, than those who spend their days in bad lighting conditions,” says Figueiro, who conducts research at Rensselaer Polytechnic Institute in New York. It is, however, more difficult to prove the link between increased light exposure and improved performance, she adds.

“Today, we have the technological tools for unlocking the many effects of light,” Figueiro says, adding that it is unfortunate that this resource is still so little used. According to Hamburg-based light planner and engineer Professor Peter Andres, “light is a basic foodstuff.”

At BASF, expertise on the subjects of light and energy in various specialist areas is pulled together by the architect Cristobal Garrido. Smart Daylight Management is the name of his project, similar to a startup, which is developing solutions to find the best way of managing daylight. “Thanks to new discoveries, ­architecture is on the threshold of a new era in light,” Garrido says. “It means that we can at last put the focus on people, and no longer on buildings.”

Lighting according to biorhythm

There are three letters that are electrifying the widest possible range of lighting experts – HCL. This acronym stands for human-centric lighting – meaning lighting that is geared to the needs of the human biorhythm. There are also three factors that could help the global HCL trend make its breakthrough. The first is the discovery by American neurologists who found a receptor in the eye that is not there for seeing but controls a human’s internal clock.

This is a discovery on which researchers such as Figueiro are building – and through which they are constantly finding fresh knowledge. Second, building designers have for a long time now had the efficient management of energy by using natural resources such as daylight on their agenda. Finally, a more recent innovation is now making it possible to put these discoveries to practical effect – light-emitting diodes, or LEDs for short. These are now so far advanced that, even where there is a lack of sunlight, indoor spaces can be illuminated in a manner identical to natural light. This HCL-supporting technology could receive an additional boost from the fact that many old lamps and light fixtures have now reached the end of their natural life and need to be replaced. ­“Especially in public buildings, there is now often pressure to get the lighting refitted,” observes Andres, who is bringing bright light to Hamburg Airport or the entrance areas of the Alte Pinakothek art gallery in Munich, Germany.

At the same time, light planning that is geared to human needs is no mere aesthetically pleasing feel-good project, as large residential and office buildings are now competing worldwide for investors. “Everyone wants to be out in front here,” says Garrido. This means that he and his competitors are increasingly preoccupied by human criteria. For example, do workers feel comfortable in these buildings? Is the design contributing to their productivity? A qualified architect, Garrido has little faith, aesthetically, in past solutions for bringing daylight into buildings. “They were violent interventions that either destroyed façades or limited the creative freedom of architects,” he says.
 

Rather than take a sledgehammer to the problem, Garrido and his BASF team are now developing finely tuned, modular light management solutions that can both be fitted on a small scale into existing buildings and installed as a complete system in new structures. The first element here is a special film on the façade with millions of tiny mirrors, and researchers like ­André Kostro, PhD, are now working on the best angle of inclination for these. The film needs to direct as much solar radiation as possible into the interior of a building through a light shaft.

Mirror, mirror – in the film

Reflective film is also used on the light tubes, which direct the rays of light from outside into the depths of the building. This natural light is absorbed by what are known as luminaires, light fixtures on the ceiling, and directed into areas that are far away from windows. They are framed by LEDs that step in if there is not enough natural light. BASF’s Smart Daylight Management is intended to work with a sophisticated measuring system that is capable of learning, stores people’s individual lighting preferences and needs, and responds according to the situation.
 

Is this a dream of the future? Not at all. Researcher Figueiro is already experimenting with a sensor wristband that measures how much daylight the wearer receives over the course of a day – and what effect this has on their well-being. One astonishing result is that, although office workers were working in areas with light levels that meet accepted standards and recommended light levels, they were not receiving enough light to stimulate their circadian system during the day.

“In such cases, a personalized sensor could be helpful,” she says. “It would communicate with the lighting system at home, which would then make up for that shortfall.” However, according to Figueiro, what does not work is trying to compensate for the morning deficit by topping up with evening rays. “Light that has a stimulant effect in the morning could significantly delay sleep in the evening,” the scientist explains. For this reason, she advises against using tablets and smartphones shortly before going to bed. “Good light planning replicates the natural daylight rhythm and supplements it where necessary. It does not manipulate,” Andres says.
 

If you subject school students to a massive light shower when they become tired, for example, you are engaging in light doping, he says. “It is roughly the same as putting espresso in children’s school milk.” That is unacceptable, of course. “Rather,” Garrido adds, “smart light management means using the natural day/night cycle as our model.”