Mass Timber Buildings: A Solution to Carbon Neutral Buildings
Wood has been widely used as building material throughout the history of construction, but its application has been limited to low rise and light frame buildings. Now, the use of wood is shifting with the game changing introduction of engineered mass timber, that is inspiring innovation in the construction sector. Builders are turning to mass timber to construct cutting edge tall wood residential towers and office buildings.
The growing use of mass timber structures, a fundamental disruption to the conventional concrete and steel construction approach, has the potential to be equally transformative for construction as electric vehicles have been for the auto industry, as this structural system can deliver aesthetically beautiful buildings with greater speed and efficiency, all while helping reach carbon neutrality.
Mass timber technology reduces construction time and costs, increases versatility in the building process, and is equally or more safe than other structures, with the added benefit of using renewable resources that sequester carbon and help reduce global warming.
What Is Mass Timber
Mass timber are engineered wood construction materials, that combine wood’s positive attributes such as it’s natural beauty and inherent wellness factors, with modern engineering to form composite products.
Mass timber is manufactured by binding wood boards with particles, fibers and veneers to form composites. The process of disassembling wood into small pieces and reassembling it together in composite form, results in a product that is significantly stronger and more versatile than a solid wood product of equal dimensions. In a solid piece of wood, strength limiting points concentrate in single areas, while engineering yield wood products with higher and predictable strength characteristics, in addition to enhancing aesthetic properties and increasing versatility.
Mass timber include structural building woods like CLT (Cross-Laminated Timber), a panelized structural wood made of multiple layers of lumber highly compressed, with alternating grain orientation. CLT can be used in all major building components, and is mostly customized for each specific project, with the exact dimensions and properties tailored for a building. The prefabrication and expedited assemblage, speed up construction process, while also reducing cost and uncertainties.
To build 1 square foot of a mass timber building, it requires 1 cubic foot of timber. And to produce 1 cubic foot of timber, it requires ca. 22.5 board feet of lumber. So for a building that requires say 100,000 cubic feet of timber, this is equivalent to 256,000 cubic feet of log volume. Bottom line, substantially more log volume is required for the finished mass timber product. And this is why the environmental benefit of using mass timber as structural building solution, is so impactful for carbon sequestration and forest sustainability. The by-product in mass timber fabrication is used by mills for the fabrication of paper and wooden pellets.
Forest Resources
Forests provide the raw material for mass timber production, and are responsible for carbon sequestration and storage that prevents global warming. The U.S. has ca. 822 million acres of forest, roughly a third of all U.S. land, and this area has remained somewhat stable for over 100 years. Of the total forest land area, approximately 515 million acres are timberland, with the rest being reserves and woodlands.
Forest sustainability is defined as consumption to meet current needs, without compromising the ability of future generations to meet their needs. Actively harvesting and managing forests to produce wood products is critical to maintain and extend the carbon cycle. After trees are harvested, they can be manufactured into ‘long living products’ that continue storing carbon while in service, like mass timber storing carbon in a building. The harvested forest is then replanted, having a net positive effect for forest growth. Mass timber is for the most part produced from wood that is certified as sustainably harvested, and the timberlands that comply with requirements receive carbon credits.
Carbon sequestration through the use of wood is one of the most impactful strategies in countering global warming. A building constructed with a mass timber structure, for every cubic meter of wood used, generates a net carbon benefit of nearly one ton of carbon dioxide equivalent, for the duration of the building’s lifetime.
The construction and operation of buildings account for 40% of global carbon emissions globally. In the U.S. alone, buildings consume nearly three quarters of the electricity, and account for half of all carbon emissions. What is worse, the increasing urbanization of the population means that 2.5 trillion square feet of building is expected to the added to the global building stock by 2060, essentially doubling the current building stock.
The AIA (American Institute of Architects) and Architecture 2030 Challenge set a goal for a 10-year timeframe to achieve net zero emissions in the building industry, and curb catastrophic climate change. This is a tall order given that currently less than 1% of buildings are carbon neutral.
A solution to carbon neutral building construction is using mass timber structures, sourced from sustainably harvested timber. And this positive trend has already started, predominantly in certain European countries but some mass timber hybrid buildings are already under way in the U.S. As of 2020, there were 1,303 construction projects using mass timber that were in process, more than doubling the number of the prior year.
The use of wood is also central to obtaining certifications for green building standards, recognizing wood’s contribution to improved energy performance, with two of the most well-known certification programs, LEEDS and Green Globes, allocating an initial plus 10% of credits just for the use of wood.
Given its positive environmental footprint, as well as enjoying the natural beauty and all the benefits to human health and wellness of living in a mass timber building surrounded by wood like Toussaint Ateliers, this trend is expected to continue.