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Nov 1, 2014 - Building

Simulating Daylight with the New DALI-Color Standard

At the University Hospital in Odense, Denmark, the radiology department in the basement is perfectly illuminated based on the time of day and the season.

The University Hospital is one of the most modern and advanced hospitals in the world. Located deep underground, the newly renovated radiology department has to get by without natural sunlight. A lighting system based on the new DALI-Color standard ensures optimally simulated daylight for the subterranean department by providing a color temperature suitable for the time of day and the season.

In order to improve working conditions for the personnel and the experience for patients, a lighting system with daylight simulation was installed that also simultaneously reduces energy consumption through the use of energy-efficient LED bulbs. The hospital decided on a solution using Color/DayLight LED lighting fixtures from the Danish firm I-NO and the 750-880 Fieldbus Controller from WAGO with the new DALI 2.0 module. The lighting fixtures communicate with the fieldbus controller using the DALI bus. The DALI module supports the new DALI Color standard (EN 62386-209), which supplements the DALI protocol with information about the color temperature or color coordinates. It is now possible to economically and effortlessly generate dynamic lighting with an extract color or color temperature. With the previous DALI standard, this was only made possible by expending a great deal of programming time and resources.

Easily Simulating Daylight with DALI-Color

Only a single DALI address per lighting fixture was necessary to configure the individual DALI Color lights, making dynamic lighting with 64 fixtures possible for each DALI line. One DALI bus suffices for the installation. The lighting fixtures were installed with WINSTA® Connectors and connected to the electrical wiring system. The DayLight lighting fixtures from I-NO were directly snapped into the suspended ceiling and connected to the WINSTA® System from WAGO. Since the lighting fixtures are manufactured from impact-resistant polymer, they only weighed 3.5 kg each. Both their installation and their use were very easy. Everything was connected to the same 5-conductor WINSTA® Installation Connector System (L, N, GND, DALI+, DALI-), and linked to the WAGO-DALI module.

Configuration Using WAGO Controllers

After connecting to the electrical installations, configuration was directly performed via the WAGO controller. Instead of physical configuration, the lighting fixtures can be completely addressed using the free “WAGO-DALI-Configurator” program. To execute this, the wiring installation was scanned, the lighting fixtures were automatically found and then addressed. For an installation of 45 lighting fixtures, the entire process took only a few minutes. A new function of the DALI Color protocol lies in the checkback signal relative to the color characteristics of the equipment. This means that the electrician has real-time information integrated into a configuration tool about which color is supported by each individual fixture.

After the lighting fixtures have been identified and addressed, they were divided into groups and connected to the associated contacts. The user interface and the color rhythm were coded into the WAGO controller using CODESYS open-source software; the colors were then implemented based on hospital personnel feedback. The system can be configured and maintained using the web browser incorporated in the system. If new DayLight fixtures or contacts are added, operators can integrate these into the WAGO controller within a few minutes.

Color Rhythm According to the Angle of the Sun

The hospital employees wanted a color rhythm that matched the natural daylight cycle. At night, a warmer, 3000K color tone was selected with a softer, invisible transition to a cooler 5500K color tone for daytime. Shortly before sunset, the light drops gently to 3000K to mentally prepare the personnel for the end of the working day. DayLight lighting fixtures feature standard support of the DALI Color functions, and an astronomical year function was incorporated into the WAGO controller so that the indoor “sun light” could faithfully recreate the changing seasons.

In addition, a room-by-room method was used in order to control the light. Each room was therefore equipped with six buttons for: 25 %, 50 %, 75 %, 100 %, cleaning and off. A simple push of a button delivers the color temperature that matches the corresponding time of day. For tasks requiring more light, 100 % or 75 % can be used. The lower intensities are suitable for more relaxed times. The cleaning button abandons the current color tone in the room and sets the light to an ice cold 5500K for maximum intensity. At this lighting level, lint becomes almost phosphorescent, which aids cleaning. After 30 minutes, the light level in the room automatically returns to the color that best supports the daily rhythm of the personnel. The simple operation of the lights has enjoyed wide acceptance among the employees in the radiology department of the Odense University Hospital.

The final program is stored on an SD card, and can be easily copied for use in other hospital departments where the personnel also desire simulated daylight. The total time required for programming and configuring the lights in the department, from beginning to end, was two hours.

Advantages in Using Open-Source Standards

  • The DALI Color installation is completely based on open-source standards.
  • Each lighting fixture uses only one DALI address.
  • The installation is scalable and easily implemented.
  • Fast electrical and physical installation
  • Expedited setup and programming
  • The installation can be integrated into existing systems, like BMS/SCADA.

Conclusion

  • WAGO-I/O-SYSTEM enables custom lighting programs, such as using seasonal functions.
  • DALI Color and WAGO provide the freedom of selecting vendors and electricians.
  • Using the DALI configurator, operators can implement changes to the installation themselves.

Text: Peter Selmer Gade, I-NO
Photo: Peter Selmer Gade, I-NO,
OUH — Odense University Hospital

    dk
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