Kanda Holdings Headquaters

A Porous Shade Created by Combining GRC and Aluminum

Kanda Holdings Headquaters

Chiyoda-ku, Tokyo
This head office building for a general distributor in Kanda, Tokyo was designed by Takenaka Corporation. The facade on the front of the building with square holes in it was created with GRC and aluminum. At first, we planned to use GRC for the entire facade, but in the end, we also used aluminum, which is lighter than GRC, for the portions where there were no floor slabs. We conducted thorough calculations concerning the heat load, lighting, ventilation, and sightliness of the facade’s innumerable holes. Making full use of analysis software, we verified that light, heat, and wind would be effectively guided and controlled before settling on the final design. The thickness of the aluminum panels for the GRC was 148mm. The inner length of one side of an opening was around 180mm. There are holes which maintain that size all the way through horizontally, and holes which grow narrower in the direction of the exterior. Of the holes which grow narrower toward the outside, there are two types with differing inclinations depending on their place of use. The inclined openings were created rationally using GRC, and were used in places facing the offices where light adjustment was necessary. Conversely, the exterior was constructed with cast aluminum in places where it didn’t matter as much if direct sunlight got in, such as the terraces from the fourth through sixth floors, and atrium spaces. In addition, in order to limit dirtying of the facade, gaps roughly 5mm in size were opened to form water channels directly under the white aluminum finishing material affixed to the outside. The facade also has the benefit of moderately obstructing lights in the offices from shining on the surrounding neighborhood at night.
An opening with a shape that is recessed toward the outside. The degree of freedom of shape was an advantage of GRC, and it was a suitable material for the opening of the slope.



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