A
nice wooden cottage with a lake view; a wooden chalet in the mountains where
you could sit in front of the fireplace with a good book and watch the snow
fall on the window; or a small log cabin in the woods, where you could enjoy
your breakfast on the porch every morning, listening to lovely bird songs,
these are the types of buildings that you most probably imagine whenever you
think of wood buildings. But could you envisage working in a wooden skyscraper?
Hardly.
130
years after the world’s first skyscraper- the Home Insurance Building- was
built in Chicago by American engineer, William Le Baron Jenney, the
construction methods and by-products associated with such large scale
infrastructure has inevitably led architects and engineers to seek new ways of
building taller and faster without having such a drastic impact on the
environment. And that has seen them revisit the most basic building material of
them all: wood.
Not
any wood is suitable for such a concept though. A type of super-plywood, called
cross-laminated timber (CTL) has been created to maintain the strength of
high-rise constructions. This effect is achieved by gluing the layers of
low-grade softwood together to create stronger timber panels. Softwood panels
are usually made of cedar, Douglas fir, pine, or redwood.
Reducing the environmental impact of
architecture
In
his book, “The Case for Tall Wood Buildings”, Vancouver- based architect,
Michael Green explains how wood will be able to absorb carbon dioxide from the
atmosphere. Unlike conventional
materials like concrete, wood can be used as it is. Natural resources like coal
and gas don't need to be burnt to produce it, so less carbon ends up in the
air. Since it is healthier for us, and for the planet, why not make the best of
it?
Timber
stores 0.8t of carbon dioxide within 1 cubic meter. In comparison, the
production of both concrete and steel are one-way energy intensive processes
that release large amounts of carbon dioxide into the atmosphere. A 10-storey building could absorb as much as
1,600 ton of carbon, in comparison to a concrete building’s comparatively low
600 tons, according to the Canadian architect.
Michael
Green proposed 20-storey (60-metre) structures made from cross-laminated timber
(CLT) panels. CLT is a durable and solid-wood material developed European
technology, to replace all structural elements above ground level.
Untreated
timber has the potential to rot when exposed to moisture and air over extended
periods of time, but CTL buildings are designed with a rain screen façade to
effectively manage moisture exposure.
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| Stadthaus Building- London |
How
long will a CTL building last for? Apparently it can last as long as a concrete
or steel building. CTL has been certified for a minimum 60 year lifespan by
Building Research Establishment in the UK, which is the equivalent of concrete
or steel.
Moreover,
wood is natural, warm (intrinsic thermal properties means lower heating and
cooling costs), compatible with other materials, non allergic and healthy to
inhabit and has attractive natural colors.
Stop cutting trees and beware of fire!
The
benefits of wooden skyscrapers are clear for all to see. Criticisms regarding cutting even more trees
down to aid the trend have also been refuted, with there now being a use for
trees already damaged. Similarly, trees can also be grown in nurseries.
But
while timber advocates such as Green hope to sow the seeds of change in the
minds of policymakers worldwide, building regulations still put a low-rise lid
on the height of timber buildings. This is based on wood’s historic reputation
as kindling for a great city fire.
Roaring
fires have ravaged city streets, in London, Chicago or San Francisco, to only
mention a few cities, wiping out great examples of grand architecture and
razing urban history to the ground. But today’s engineered timber develops a
protective charring layer that maintains structural integrity and burns very
predictably, unlike steel, which warps under the intense heat.
Europe leads the way in the concept’s
innovation
Until
now, America’s conservative building regulations and a lack of interest from
developers and their customers have meant few interesting wooden buildings have
been built there. In contrast, Europe, Australia and especially Canada are
embracing the emerging technologies.
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| Forte Building- Melbourne |
So far two high- rise buildings made of wood
have been erected in the world: nine-storey Stadthaus in London and the
10-storey Forte Building in Melbourne.
Also in Bergen (Norway), a 14-storey wooden building is currently under
construction.
Forté,
the world's tallest timber apartment building, raising 10 floors above the
ground only includes 23 apartments and was built in 16 weeks.
