Downtown woodsy
In the 19th Century it was steel. Then later, in the 20th Century concrete rose to prominence. Now in the 21st Century, wood is the rising star of the building industry, for its low carbon footprint and renewable resource attributes. To truly build Eco Cities of the future, many of the materials used today will eventually be swapped for more renewable resources. Wood, specifically engineered wood, is already making strides in large buildings today.
The use of wood for tall building construction is not a novel idea. In fact, the five story Horyu-ji pagoda in Japan is over 1500 years-old. Today, the increasing number of code-approved, engineered wood construction projects are reaching five, six and even ten, stories in Europe and Australia. CREE by Rhomberg has two buildings in Austria, its global headquarters called the LifeCycle Tower ONE and the IZM Montafon, set to be one of the largest tall timber buildings in Europe by area.
Two main types of engineered wood products dominating the tall wood building race today are Cross Laminated and Glued Laminated Timber (glulam). These “engineered” wood products combine smaller sections of wood into larger posts, beams and mass timber panels. These wood products are strong and rigid enough to replace steel and concrete as structural elements in large buildings, even up to 30 stories.
As timber is a carbon storage mechanism, buildings built primarily from wood inherently have a low carbon footprint. With proper forest management, trees and their timber can be a sustainable, renewable resource. One aspect of managing sustainable forests is to replace old and damaged trees with young ones, which grow faster and absorb more carbon from the atmosphere. Older trees, absorb less carbon and if allowed to die all the carbon they stored is released back into the air or ground. It therefore makes sense to sustainability harvest forests and produce engineered lumber and other wood products to store carbon.
While most tall buildings are still built using on-site processes, one firm has developed a prefabricated, systemized timber based approach.
Comments
I am a big fan or sustainable design and new innovations. To state the obvious, though, my understanding of current fire codes for highrise buildings is that columns include 3 hrs of fire protection, and beams and slabs include 2 hrs of fire protection. These numbers are not based upon how long it takes the fire fighters to get to the fire. It is based upon all other systems failing and all combustable materials "burning out" of the building so nothing is left to burn.
How can a highrise wood structure achieve this comparable level of safety?
It is great to innovate, but loose the "spin" and be real about the life safety issues of a 30 story building made of wood. When a comparable level of life safety due to fire can be quantified, I'm all ears.
The concept of using wood construction to store carbon and cutting down old growth as quickly as possible to replace with young trees as a good policy to reduce CO2 levels in the atmosphere is based on an incomplete understanding of how forests function. It is the kind of claim based on a mechanistic/reductionist view of the biosphere that is promulgated by the timber industry in order to get it's hands on the last old growth timber out there.
Forests are much more than the sum of their parts. Dead standing and downed old growth trees provide both habitat for the creatures that make their homes there as well as fertilizer for the next generation of plants and trees. Large dead logs also are act as water retaining reservoirs during dry seasons. Intact old growth forests protect water quality and reduce flooding. These are only a few of the functions of intact forests. The author proposes a silvicultural policy that would eliminate these important functions of intact mature forests. It's a little like suggesting that we bulldoze subdivisions and store them in a large container to keep the carbon out of the atmosphere permanently. Never mind the impact to those that live there.
Also ignored is the carbon returned to the atmosphere from logging, milling, marketing, construction and waste. All of these activities add carbon to the atmosphere.To make any intelligent comparison of a net atmospheric CO2 reduction between intensively managed short rotation silviculture and a natural old growth forest left to decompose and regrow without management must include accounting of all the carbon involved in these two scenarios.
While the article is important in pointing out that wood can be renewable resource and is potentially a more sustainable building material than steel and concrete it strays into an area of science that is clearly outside the authors purview and makes unsupported claims about the best way to manage forests for reducing CO2 in the atmosphere. the author should stick to his/her area of expertise and avoid passing off opinion as science.
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