Towers made of timber could herald a new environmentally friendly era of construction.
An Opportunity for Innovation
Architect; Professor, John H. Daniels Faculty of Architecture, Landscape, and Design, University of Toronto.
In architecture, engineering, and forestry sectors around the world, there is a mega-buzz about forthcoming high-rise towers made of wood. Imagine a 20, 30, or even 40-storey condominium or office tower that has timber structural-members and is clad in wood. The modernist preoccupation with high-carbon-footprint concrete and steel may soon take a back seat to the innovation of towers constructed of wood. The earliest ventures in this direction started in Japan a decade ago. But numerous projects are now also on the drawing boards in Austria, Norway, Australia, and Canada.
With encouragement and support from the British Columbia government and its forestry division, architect Michael Green of Vancouver-based McFarlane Green Biggar Architecture + Design, is moving fast with proposals for 20- to 30-storey, timber-constructed towers that are highly earthquake- and fire-resistant and hugely eco-friendly.
A provincial study to be released later this month will evidently not only make a case for the feasibility and safety of wood-constructed towers, but will also heavily promote the economic benefits for British Columbia. B.C. is indeed moving ahead on these fronts, having recently changed its building code to allow six-storey wood-frame construction. It is likely that research, development, and testing will soon lead to even more radical changes in the building codes for timber and timber-composite construction. (For example, although inherently more flammable than steel or concrete, if a timber member has sufficient size and mass it will burn slowly before structural failure.)
Green is clearly leading the way into exciting architectural territory. However, the recent claim that Green is developing “the world’s first ‘timber skyscraper’” is off the mark. Nearly a decade ago, Tokyo architect Kazuhiro Ishii commenced research for a 30-storey timber tower in the city’s Akasaka district. He worked with testing laboratories for several years to prove the viability of the project in terms of earthquake resistance and fireproofing. In 2008, he won his case. Now Mori Building Co., Ltd. is moving ahead with the remarkable 32-storey, wood, residential tower, which has “air gardens” – elevated outdoor green spaces – every third floor. In a nation reeling from the recent, devastating earthquake and tsunami, the innovation and optimism represented by Ishii’s tower will be a welcome sight.
British Columbia and Canada should not just move ahead gingerly with innovative high-rise timber designs and new kinds of wood-composite construction. Rather, the initiative should go full-throttle and thrust Canada into a leadership position on these fully “environmental” concepts.
A Question of Safety – and Courage
Architect; Director and Professor, McGill School of Architecture.
Innovation is good, but it needs to be tested.
When you talk about it from an environmental point of view, wood skyscrapers are a great idea. After all, these structures are made using renewable material. However, it all boils down to a question of safety. It is commonly known that wood-constructed buildings can withstand earthquakes better than those made of steel or concrete. But there is still much concern around the issue of fire.
Steel is formed in temperatures around 3,000 degrees Celsius. So if a building made of steel reaches that temperature – which is entirely possible – the steel beams are likely to bend. This is what happened, for instance, with the collapse of the World Trade Centre towers: the trusses were made of steel, and when they reached the critical temperature they all buckled, causing the building to collapse.
To completely burn a large log (such as a beam or a column) would actually require a higher temperature than that which is required to bend steel.
Skyscraper steel is coated with foam to prevent fires. If the same strategy were applied to wood structures, it would be possible to protect them as well. But, here in Canada, we are not at the stage where we will even attempt to test it yet.
We have tons of experience working with steel structures; we know what will happen when there is a major fire in a steel or concrete building. On the other hand, we’ve never built a wooden high-rise structure, and so have not had the opportunity to test it. The nature of Canadian building codes is that they are based on trial and error – they are furthered not by estimating, but by experimenting. Furthermore, the damage caused by Japan’s recent earthquake will make people re-evaluate strategies for building, in the hopes of guarding against such disastrous collapse.
Municipalities and municipal officials need to take risks. And, from my experience, they are the least likely to do so. Once city officials have given permission for architects to build something, they are, to some degree, held liable if something goes wrong. This is one of the largest obstacles to architectural innovation.
So the second hurdle – after figuring out how to protect wood from flames – is finding a municipality that will permit a wooden high-rise to be constructed. In Canada, it has only been in the last decade that wooden buildings have been allowed to be above three storeys. Some wooden buildings have been five or six storeys high, but none have been more than 10.
Unfortunately, homebuyers are also not risk takers. When people buy homes, it’s usually the biggest investment they will make in their life. So they are, of course, reluctant to gamble. Thus, it might be a bigger problem to build a wooden condominium building than it would be to build a wooden office tower.
However, if an architect were to find an enlightened community and someone willing to build such a tower, it is possible that experimentation could take place, leading the way for the future of wooden towers in Canada. As in the life of any new innovation, someone must take the first step.