Urbanization and the rapid growth in population are driving the global energy demand higher. Keeping up with the demand for energy remains as one of the greatest challenges of the 21st century.
Buildings are constantly being erected to maintain enough space for population growth, but the life cycle of a building is one of the most energy-intensive processes in the world. Buildings, building materials, and subsequent construction components consume nearly 40 percent of the global energy demand.
While there are many reasons for the substantial amount of energy used to build and maintain buildings, one of the major environmental concerns arises from the fabrication of cement, one of the basic ingredients in concrete.
It is a utilitarian material used in the fabrication of bridges, skyscrapers, and residential foundation, among many other uses. But the cement industry is one of the worst contributors of pollution. Its production accounts for about 5 percent of global carbon dioxide (CO2) emissions alone.
The Problem with Concrete Construction
Lifestyle changes and with a society bent around space, the demand for newer and bigger buildings is ever increasing. Old buildings are torn down to make way for the new, and the lifespan of the average building is decreasing. But the many of the buildings which are cleared away are destroyed long before their useful life expires. Demolishing concrete structures comes with complications of its own, such as its tendency to leach into and poison topsoil and water bodies.
"Buildings are one of the largest consumers of global resources and all energy produced, and are primary contributors to greenhouse gases and solid wastes."
"Buildings are one of the largest consumers of global resources and all energy produced, and are primary contributors to greenhouse gases and solid wastes," tells the MIT Mass Timber Design team, a small group of MIT researchers leading a new initiative to change the way buildings are made. "[So] the need for energy-intelligent building prototypes is more significant than ever."
New building materials are constantly being developed and new techniques employed, but many institutions, including MIT, are investigating using ancient alternative technologies which are cheaper, and perhaps more durable than concrete and steel buildings.
Building Modern Wood Buildings
It was the Romans who arguably perfected concrete, and many of their structures still stand today. While their structures stood the test of time, the recipe for Roman concrete, which still remains as one of the strongest materials created by man, was ultimately lost when the Roman Empire fell. Following its collapse, concrete became scarce and was largely abandoned. It would not be until the mid-18th century before steel and concrete would regain popularity.
However, civil engineers and architects of today are reverting modern building practices to re-incorporate timber as a primary structure and construction material. New technologies are being investigated to replace steel reinforced concrete structures with mass timber housing. Universities such as the University of Maryland and MIT among others are pioneering new techniques to readapt wood to the modern world.
Steel reinforced concrete structures are often considered long-term building solutions. To many living in wooden framed and drywalled lined, the idea of a house lasting a century or more is almost inconceivable. Buildings are torn down long before then, but typically before their usable lifespan is up.
Many do not plan on living in a small house for long and make plans to upgrade to more floor space. The demand for big houses is increasing, and so smaller houses are being torn down to make way for the new.
MIT’s Mass Timber Design Longhouse
Changing the mindset behind short-term wooden constructions is MIT. A group of researchers at the university are leading an initiative to investigate new mass timber designs- wood-based buildings designed to be more efficient and cheaper than, yet just as durable as, concrete and steel buildings.
The team proposes building mass timber longhouses - large wooden engineered houses built from massive pieces of timber.
The Longhouse was developed by a cross-disciplinary team in Mass Timber Design, a design workshop in MIT Architecture that explores the future of sustainable buildings at the intersection of architecture and technology. Project credits include: (Research Scientist) John Klein, (Design-Engineering Team) John Fechtel, Paul Short, Demi Fang, Andrew Brose, Hyerin Lee, Alexandre Beaudouin-Mackay.
“Mass timber, a wood-based building design, and construction technology, has received attention over the past few decades given its efficiency, speed, precision and versatility in construction for low to high-rise applications. Mass timber buildings are becoming more common throughout North America, most notably due to the technology’s environmental benefits and the potential impacts it can have on America’s forest health and restoration. MIT Mass Timber Design, a design workshop at the Massachusetts Institute of Technology, has explored the design and engineering potential of these technologies and developed a mass timber-building prototype: The Longhouse.” tells MIT.
By incorporating modern technology with tech from the past, they propose building a high-tech wooden multi-purpose building on the MIT campus. While it is taking a step back in time, the building will be outfitted to be an energy producer.
“The building orientation and the depth and angle of the sawtooth roof can be tuned for local solar conditions and natural daylighting needs. A low window to wall ratio with a highly insulated envelope allows for an energy efficient building. The project utilizes Computer Numerically Controlled (CNC) manufacturing processes to enable a prefabricated modular system for efficient assembly,” the team describes.
“In order to achieve a large spanning high bay space for flexibility, the building is engineered as a series of timber laminated veneer lumber (LVL) arches spanning across the building’s shorter dimension. Each arch utilizes a thin-walled triangular profile to minimize deformations in the structure and provide overall rigidity to the building.”
At the moment, it is just an idea proposed to tackle the concrete energy and pollution epidemic. But they are not alone in their mission, many other companies and organizations are leading similar initiatives to incorporate sustainable timber designs as a long-term building solution.
Benefits of Wood as a Construction Material
Wood is both light and strong, and it maintains excellent insulation properties without requiring additional resources. Unlike wood, concrete is a poor insulator and requires additional material to keep it better insulated.
Concrete is typically more expensive, but for large buildings, steel and concrete have been the preferred materials for construction. In recent times, however, new technologies are improving the durability of timber, making it more environmentally and economically viable than its concrete counterpart.
But perhaps most importantly, according to a study led by CORRIM (Consortium for Research on Renewable Industrial Materials), the lifecycle of steel and concrete results in 26% to 31% more greenhouse gas emissions than that of wood.
As weather systems continue to worsen, it is becoming more vital than ever to reduce greenhouse gasses. With the movement and introduction of carbon taxes and other similar pollution tax, there may also be other saving incentives for companies to make the transition.
Timber constructions can also be more aesthetically pleasing and when harvested appropriately, is considered to be a renewable resource. It is not without its problems, however.
The Problem With Wooden Buildings
Wood is renowned for shrinking and swelling due to changes in moisture content. The effects are noticeable in even small constructions of residential housing. Drywallers often wait a few days or more for newly framed houses to settle before attempting to finish any wall. If the drywall is placed before the house settles, it will almost certainly crack - a problem many apprentices and DIY individuals come to learn.
Without special treatment, wood is also rather flammable, an undesirable trait especially when considering large complexes and their safety. Wood is also susceptible to discoloration and mold, however, with proper intervention, damage can be minimized for hundreds of years.
On the other hand, mass timber is inherently fire resistant due to the charring effect of the material in bulk
Other Wood Projects in the World
MIT is far from the only institution investigating the implementation of wood construction.
Earlier this year, the University of Maryland invented a “super wood” made from the fibers of wood and transformed into a super-strong resource.
"It is as strong as steel, but six times lighter. It takes 10 times more energy to fracture than natural wood. It can even be bent and molded at the beginning of the process." said Teng Li, the co-leader of the team and Samuel P. Langley Associate Professor of mechanical engineering at UMD's Clark School.
Another company by the name of Lever Architecture is finalizing a proposed a 12-story wooden skyscraper in Portland, Oregon. Their design was approved last year and the company is currently in the works of finalizing permits to begin construction. When constructed, it will be America's first wooden skyscraper.
Sumitomo Forestry, a Japanese based company, also plans on building a wooden skyscraper. However, it is poised to be the tallest wooden skyscraper in the world, set to be complete by 2041. According to the company, 10 percent of the 70-floor tower would be steel. The rest will be made from 180,000 cubic meters of original wood.
Naturally, there are many solutions to the construction-energy epidemic of the 21st century. While there are many modern materials which hold promise to eventually surpass concrete and steel buildings, perhaps the best step forward, is actually taking one back.