Japan plans world's tallest wooden skyscraper

Japan plans world’s tallest wooden skyscraper

Japan is planning to build a 70 storey skyscraper made of wood. The structure would be earthquake proof and could help revitalise the country’s timber industry.

The design concept for the “W350 Project” in Tokyo includes wraparound balconies draped with foliage to provide occupants access to fresh air, daylight, and views.

The Japanese construction company Sumitomo Forestry thinks a city could reduce its carbon footprint by building with wood.

To demonstrate this vision and bring attention to the possibilities of mass timber construction, the company plans to build a 1,148-foot (350-meter) tall wooden tower in Tokyo.

Developed by Sumitomo Forestry’s Tsukuba Research Institute in collaboration with architecture firm Nikken Sekkei, the “W350 Plan” concept is a 70-story mixed-use building including residential, office, and retail space.

It will require some 185,000 cubic meters of timber. The design calls for a highly efficient “braced tube structure” that is 90% wood.

Steel braces, diagonally inserted into the structural framework of wooden columns and beams, are designed to prevent damage caused by wind or earthquakes.

Japan plans world's tallest wooden skyscraper

Japan plans world’s tallest wooden skyscraper

The benefits of wood

There are many reasons why building with wood makes sense, not least of which—especially for seismically active places like Japan—is the performance of timber-framed buildings in earthquakes. Because wood construction is lightweight and ductile, in an earthquake a timber building will flex, absorbing and dissipating the violent lateral forces.

As for environmental benefits, building with sustainably harvested timber in place of concrete, steel, and brick could reduce global carbon by nearly a third. (For a detailed discussion of the benefits of timber construction, see our feature article, Engineering a Wood Revolution, which includes specifics about the impact of wood construction on carbon sequestration.)

whole-building life-cycle assessment of the eight-story, 29.5-meter Wood Innovation and Design Centre at the University of Northern British Columbia, completed in 2014, found that the project reduced the carbon cost of construction by more than 400 tons of carbon dioxide (CO2) by using wood instead of concrete and steel. And the project sequesters an additional 1,100 tons of CO2—equivalent to the annual emissions of 160 households.

According to Sumitomo Forestry, the W350 tower would sequester 100,000 tons of CO2.

Improving Japan’s forests

With the W350 project, Sumitomo Forestry sees benefits beyond reduced carbon emissions and carbon sequestration. By promoting the use of wood for high-rise urban buildings and increasing demand for timber, the hope is to revitalize Japan’s forestry industry while making it more sustainable.

The company believes that greater demand for domestic timber would promote better management of the country’s forests. In turn, increased maintenance of the forests would keep them healthy and preserve their ability to absorb CO2.

What about the cost?

A chief drawback of building with wood is the high cost involved. If built today, the W350 project would cost about $5.6 billion—almost double what a conventional high-rise project would cost. However, between now and 2041, Sumitomo Forestry believes that research and technological advancement in wood construction will make the project more economically feasible. In fact, a main goal of the W350 Plan is to drive innovation that will lead to the development of new materials and methods; this, in turn, would make large-scale wood construction increasingly affordable.

A number of large wood buildings have been completed in the past several years, indicating a steadily growing interest in large-scale wood construction:

Further information

April 10, 2018
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