TOKYO SKYTREE^®

Japan
Public Spaces
Towers / Monuments

1,995 all-LED lights curb energy consumption while beautifully illuminating this symbolic Tokyo landmark.

Customer needs

The operator of this tower, a new symbol of Tokyo, wanted to light-up it entirely with LED.

TOKYO SKYTREE^®, the world’s tallest*1 broadcasting tower (634 meters) opened in spring 2012. When planning for the lighting for TOKYO SKYTREE^® began, HID (high-intensity discharge) lamps were to be used, but in light of the need to conserve energy, use of LED was considered instead.

However, at the time LEDs had just established a presence on the market and were still largely limited to small spotlights for stores, etc., and were not envisioned as floodlights that could reach distances of 140 meters or more. Also, there were problems with heat release even with standard LEDs, and nobody knew how to address this issue with LEDs of unprecedented high output.

*1 Among free-standing broadcasting towers, as of December 2011

Our goals

To develop high-powered LEDs, special LEDs that faithfully recreate color, and technology for control of light sources reaching over 140 meters.

“Iki,” the stylish, resolute spirit of Edo©TOKYO-SKYTREE

Working in concert with the architects, lighting design supervisor Hirohito Totsune produced a plan for two lighting styles to be used on alternating days: "Iki" the spirit of Edo, and "Miyabi" for its aesthetics. According to Mr. Totsune, "Iki" is represented as pale blue light with the motif of the water of Sumida River, and focuses on the central pillar of the tower. "Miyabi," the aesthetic sense, expresses an elegant and dignified image of the tower by showing its intricate steel structure with the theme color purple which reflects the representative color of Edo.

To faithfully recreate the colors Mr. Totsune envisioned, we employed Panasonic’s proprietary high-precision color recreation technology. Panasonic developed a new LED package containing blue LEDs and fluorescent substances, and the inclusion of these substances enabled an accurate replication of the elegant shades.

“Miyabi,” the elegant aesthetics of Edo©TOKYO-SKYTREE

Until that time, LED had been thought unsuitable for lighting because of its insufficient luminous flux. In particular, it was a challenge to develop floodlights with both the power and the precision light distribution to illuminate the pinnacle of the central gain tower with a pin-spot from a distance of 140 meters. Conventionally, LED light distribution control has been carried out with lenses, but when using lenses it is impossible to produce large fixtures, and distortion occurs as well. For this reason, it was decided instead to employ a double-width 600mm large reflective place. Double the diameter means four times the surface area, meaning that only one LED fixture could be installed in a space large enough for four fixtures. However, preliminary experiments produced positive results, and the conflicting issues of limited space and need to minimize the number of LED units used was overcome. Supplementary reflective plates and louvers were also used to prevent light leakage.

It was necessary to take preventive measures against overheating, as it can shorten the lifespan of LED light fixtures and decrease luminous flux. Heat-radiating design criteria compatible with the environment at the site were determined so as to secure a light source lifespan of 40,000 hours. Simulations were carried out according to the criteria, and effectively heat-radiating, highly durable LED light fixtures were developed. The structure is designed so that components or units will not fall even when hit by gale-force winds or lightning.

Example of installation of fixture on gain tower

Highly challenging ultra-narrow angle light distribution was achieved through development of large-scale reflective plate.

Effects

Approximately a 43% reduction in power consumption realized with the "Iki" lighting pattern.

LED light fixtures accurately recreate highly specific colors thanks to light distribution design, color recreation technology, and dimming adjustment technology independently developed by Panasonic. Development of specialized LED lighting devices made it possible to employ LED for a total of 1,995 light fixtures illuminating the TOKYO SKYTREE^®. With highly energy-efficient LED light fixtures controlled by a high-speed remote control system, the power consumed by the “Iki" lighting pattern (1,588 fixtures) is 43% less than with conventional light sources*2 by Panasonic. A significant amount of other development is going on in the vicinity of the TOKYO SKYTREE^®, and a wide range of other Panasonic solutions are being implemented.

*2 High-efficiency ceramic metal halide lamps + filters, with LED fixtures used in some places (timed lighting, lights at steel structure intersection points)