Nihombashi Mitsukoshi Main Store | Kengo Kuma and associates

A. Project Outline
Nihombashi was once the starting point to connect five important land routes during the Edo period. Since then it has been a bustling neighborhood with historic architecture, traditions, and culture still alive today. In 2016, Nihombashi Mitsukoshi was recognized as an important cultural asset. The architectural design concept for this renovation is “trees” to gather people and “paths” to move people. Historical parts of the building were saved and incorporated with new spaces. On the 1F of the main building the lighting design is based on the architectural theme of “a shining, white forest.”
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B. Project Detail
The tree canopy, leaf-shaped panels topping structural posts, is a modern design with art deco influences. The tree canopy expands across the entire sales floor creating a beautiful gradation of light and filling the space with a sense of brightness. At each entrance, a specially designed ceiling greets customers. This gate of light, is a continuation of light reaching from the tree canopy toward the ceiling, creating a sense of euphoria for customers and wrapping the sculpture-like design in light. In order for the design concept of a “shining, white forest” to become a reality, we extensively pursued two ideas, “beautiful gradation of light” and “adherence to a white palette.”

Beautiful Gradation of Light
Fixtures were mounted one-by-one behind trapezoid-shaped leaves made of aluminum paneling. In conjunction with the architect and manufactures we made adjustments and verifications through carefully conducted mock-ups to achieve a soft glow of light from in-between canopy leaves. Leaf shape, material, light sources, the angle of reflectors, and fixture placement were all meticulously tested.

An artistically, beautiful gradation of light was very difficult to achieve and brightness balance became a very important factor. Some surfaces reflected too brightly and making smooth alterations was important, however each leaf shape was different and the space between leaves was very tight. Therefor, some mounting detail is fixed to reflect twice, making room between the light source and illuminated surface, to control the intensity of brightness.

The next challenge was to eliminate reflection off of aluminum paneling from the light source because the intense brightness of each reflection was very noticeable. In order to create a beautiful gradation of light containment was necessary. A matte finish solves most of the problem, but a matte finish on white paneling dirties easily. It was a difficult challenge. In the end, the maintenance clash was solved using a 20% semi gloss finish to keep reflection to a minimum.

The last problem to solve was unnecessary shadowing on the panels. In order to contain brightness, wide distribution fixtures were specified, however shadows from lower panels showed on upper paneling. In order to cut shadows, mounting position and special hoods were carefully considered.

A White Palette
In order to deliver a “shining, white forest” we aimed to create a perfectly, white space by unifying color temperature at 3500K, including all indirect lighting, ambient lights, tenant accent lighting and all other lighting systems. The color temperature of all LED fixtures needed to be the same, but coloring differences arise with different manufactures. If all light sources are the same brand it looks white, but compared with other brands tints of red or green are visible. In a very white environment like this, different color tones are extremely clear and create an almost sickening space. Fixture performance is important, but color tones were an even more determining factor. Also, color tones off reflective surfaces in the tree canopy are not directly visible, but had an impact and were another factor that was carefully studied. 

Text © Lighting Planners Associates