As the wind swiftly blows clouds across the sky, the light is in a
constant state of change. The feeling of spaciousness and freedom we
experience outdoors is exactly what researchers from the
Stuttgart-based Fraunhofer Institute for Industrial Engineering IAO
replicate indoors: a luminous ceiling that extends across the entire
room simulates lighting conditions which resemble those produced by
passing clouds – conveying the impression that you are sitting
outdoors.
|
| The
dynamic luminous ceiling gives office staff the pleasant feeling that
they are working under the open sky. © Fraunhofer IAO |
The innovative luminous ceiling, which was developed by the Fraunhofer
researchers in close collaboration with their partners at LEiDs GmbH,
consists of 50cm by 50cm tiles. “Each tile comprises an LED board
with 288 light emitting diodes (LEDs),” states Dr. Matthias Bues,
head of department at the IAO. “The board is mounted on the
ceiling. A diffuser film in matt white is attached approximately 30cm
beneath the LEDs and ensures that the individual points of light are
not perceived as such. This diffuser film creates homogenous lighting
that illuminates the room throughout.”
The researchers use a combination of red, blue, green and white LEDs in
order to produce the full light spectrum. This combination makes it
possible to generate more than 16 million hues. What’s more, the
white LEDs are more energy efficient than the colored lights, which
keeps the energy costs to a minimum.
The main focus in developing the virtual sky was to simulate natural
lighting conditions on a cloudy day. To achieve this goal, the
researchers carefully examined natural light to find out how –
and how quickly – the light spectrum changes when clouds move
across the sky. “The LEDs allow us to simulate these dynamic
changes in lighting in a way that is not directly obvious to the naked
eye. Otherwise the lighting might distract people from their work. But
it does need to fluctuate enough to promote concentration and heighten
alertness,” says Bues.
The results of a preliminary study indicate that users find this
dynamic lighting to be extremely pleasant. The study involved ten
volunteers who carried out their daily work over the course of four
days under these lighting conditions with a lighting surface of 30cm by
60cm. Throughout the first day, the lighting remained static. On the
second day, it fluctuated gently, and on the third day the fluctuations
were rapid. On the fourth day, the participants could choose which type
of lighting they wanted, and 80 percent opted for the fast, dynamic
lighting.
A prototype of this virtual sky has now been developed that contains a
total of 34,560 LEDs spanning an area of 34 square meters. At full
power, the “sky” lights up with an intensity of more than
3,000 lux, but 500 to 1,000 lux is sufficient to create a comfortable
level of lighting.
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