If the 20th century was the century of the Skyscraper, then the 21st century is shaping up as the century of the PLYSCRAPER —– a tower block made entirely from wood.
A PLYSCRAPER is a skyscraper made out of engineered-lumber such as cross-laminated-timber (CLT), which is composed of dried lumber which is stacked in a 90degree “L” shape, and fully glued over. It makes for a strong, flexible green building. By the end of 2015, an estimated 40-48% of new non-residential constructions, by value, will be green. The Obama Administration, in co-operation with lumber industry groups, is currently offering a $2million prize for the most innovative PLYSCRAPER design. With green buildings on the rise and stimulating the economy, the timing of this contest should come as no surprise.
Despite the historical reputation of wood for great city fires —— London in 1666, the Great Chicago fire of 1871 and San Francisco in 1960 ——- WOOD is making a comeback as “construction material” and how. Vancouver-based architects MGA recently completed a 97ft wooden building. Next year, in Vienna, construction will begin on a 275ft PLYSCRAPER, and Stockholm may build a 34-storey wooden apartment by 2023. Others in the pipeline are from Canada to Australia to Europe. Vancouver-based architect Michael Green, says the momentum is gaining as new engineered-woods allow for greater strength and heights in buildings. Moreover, faster construction times and a softer environmental impact, could the building material of the past be the future of construction ? But, he said, news of taller wooden structures is sprouting up all the time. “There seems to be a new announcement every 2 or 3 weeks. We’ve got one in Vancouver for 18 storeys, and in Vienna there’s one for more than 20 storeys. We’ve done research in high earthquake zones, that show 30 storeys is FEASIBLE. We certainly think we can go up to 40 and higher.”
Michael Green said that new developments in engineered-woods —— small wood components that are glued together to make large panels for a building —— are a “game-changer” for construction. Mass timber panels, in particular, cross-laminated-timber (CLT) are becoming established as a quicker, greener and, eventually, cheaper alternative to concrete and steel. One great bonus of the material is the “speed of construction” —— panels can be made to measure, in the factory, with openings, windows and doors. While the main advantage of working in wood are manifold —— it is flexible, robust and easily worked, Green says that wood may be the only material to address the growing problems of urbanization. Wood has not been looked as “urban material”, so we looked at how it could be the contributor to urban environments. There are a whole host of advantages. Steel and Concrete have huge “carbon footprints”. Concrete accounts for about 6-8% of man’s greenhouse gas emissions, whereas Wood “sequesters” carbon dioxide and gives us a vehicle to create “carbon-neutral buildings.
The energy used to harvest Wood is much less than the enormous amount required to produce Concrete and Steel. Green says, “There is no other building material that is grown by the Sun. We’ve calculated that the North American forests grow enough wood for a 20-storey PLYSCRAPER every 8-10mins. Ultimately, building in wood, creates an economic incentive to plant more forests. The climate story is really happening at both ends of the argument ——– by using more wood we encourage countries, around the world, to plant more trees. About 20% of man’s carbon footprint comes from “de-forestation” and this creates an important incentive for “re-forestation”.
In terms of “carbon footprints”, a 20-storey PLYSCRAPER put against its counterpart in Concrete and Steel, is equivalent to taking 900 cars off the road for a year. But the established nature of concrete and steel means that CLT will not replace urban building materials overnight. Concerns over fire and inherent problems with its acoustic qualities (apartments need additional acoustic measures to keep noise from travelling) have meant that the construction establishment has been slow to come to the party. In Vienna, for example, the Austrian Fire Services are working with architects to test their plans. —– “The main factor is that everyone wants to build higher and higher buildings An 84-metre-high building, in Europe, is not usual and there are a lot of necessities that have to be realized,” fire service spokesman Christian Wegner told The Guardian newspaper, “a few of us were upset because it was crazy to present an idea like this that has not been discussed with everyone yet. They have to carry special tests on the correct combination of concrete and wood. We also want to develop a more “fail-safe” sprinkler system. I expect they will pass the tests, but if they develop the buildings, as they say they will, it will be a serious project.”
Green counters that CLT is as fire-resistant as other new-builds made by traditional means and likens its ability to burn to trying to set a redwood on fire with a lit match, with any charring creating an “insulation layer” that protects the wood underneath. Even so, the industry remains largely sceptical of a process that —- while having obvious advantages in terms of speed —- is still on par with steel and concrete constructions in terms of cost. Green said, “It will become cheaper, but it’s too new to be significantly less expensive, and the difficulty lies in competing with a “well-honed” and “century-old” system of designing buildings and budgeting for concrete and steel. The culture of building and the culture of developing buildings is very “conservative”, Green said, “The hardest part of my job, is not the engineering and the design or the innovation, it’s really about changing the public’s perception of what is possible.”
Ultimately, buildings of the future are likely to be a mixture of wooden components and concrete and steel, thus combining the “stability of concrete” with the “flexibility and speed of wood.” Leading timber specialist at ARUP, Andrew Lawrence, said that, “Clients are missing a trick with wood. Dollar-for-dollar as a pure construction material, wood can still struggle to be cheaper than concrete. What you need to do, if you want an economic solution, is to think about all the aspects from the outset. You will save on the program, because it’s all dry and is quick to erect and potentially, if you are making an office building, you can leave a lot of the wood “exposed” saving on the cost and time of installing finishes. Moreover , clients will gain a building that looks good too. Studies show that people are happier inside wooden structures.”
PLYSCRAPERS could be the future of flat-pack-cities around the world. In Christchurch —- The Merritt Building welcomed its 1st multi-storeyed timber structure this year, there are plans for Vancouver, and, the talk is China could follow. Just as the world’s 1st Skyscraper, built by William Le Baron Jenney in Chicago in 1884 (called a spindly steel skeleton) solved the issue of the dense, stunted buildings in the 19th century, architects and engineers are seeking new ways of building faster and taller without having a drastic impact on the environment. And, that has seen them revisit the most basic building material of them all : WOOD.
Super firm SOM —– the architects behind the One World Trade Centre and the Burj Khalifa —- are considering using wood for high-rise constructions. Wooden Skyscrapers, or should we say PLYSCRAPERS are “smoking hot.” —COULD YOU, WOOD YOU ????????