W350 Project Japan: an Environmentally and Socially Sustainable Community in a Wooden Skyscraper

Nikken Sekkei | Sumitomo Forestry

Building outline: Height – 350 m, number of floors above ground – 70 floors
Building area: 6,500 m2
Architectural area: 455,000 m2 (6,500 m2 × 70 floors)
Structure: Wood and steel hybrid structure (Internally, pure wooden structure)
Building use: Stores, offices, hotels, residences
Amount of timber used: 185,000 m3
Total construction cost estimate: Approx. 600 billion yen

The aim is to create environmentally-friendly and timber-utilizing cities that become forests through increased use of wooden architecture for high-rise buildings. This concept plan has been prepared primarily at Tsukuba Research Institute, Sumitomo Forestry’s research and development facility. The institute is expanding possibilities for wooden buildings as a roadmap for future technology such as the development of building methods, environmentally-friendly technologies, and trees that become resources and building materials.

Building Outline

The planned structure is a hybrid wood and steel structure made from 90% wooden materials. It will use a braced tube structure* in which steel frame vibration control braces (diagonal braces) are positioned inside a column and beam structure, made from a combination of wood and steel. The outermost side is designed with balconies that continue around all four sides of the building. The balcony part gives the high-rise building a space in which people can enjoy fresh outside air, rich natural elements and sunshine filtering through foliage. The greenery connects from the ground to the top floors through the balcony part, and it offers a view of biodiversity in an urban setting. The interior structure is of a pure wood, producing a calm space that exudes the warmth and gentleness of wood. Nikken Sekkei Ltd. collaborated in the design of this building.

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* Brace tube structure: A structural system composed of braced tubes made from columns, beams and braces. A brace is diagonally inserted into the incorporated framework assembled by columns and beams to prevent deformation of the building due to lateral forces such as earthquakes or wind.