The challenge is to design and construct these future buildings in a way that’s both efficient and sustainable. Construction tends to be slow. And most buildings are environmentally unfriendly both during construction and operation – which ultimately makes them expensive.
What would it take to construct our cities in a way that’s both more efficient and more sustainable than today? At Covestro, we believe new construction models and innovative materials can build a brighter future for the cities we call home.
Affordable housing is a cornerstone of healthy, diverse cities, and it’s necessary for citizens’ wellbeing and economic opportunity. But it’s becoming harder and harder for urban dwellers to find comfortable, affordable places to call home.
In most cities, homes and residential buildings are still constructed the way they were 80 years ago. Despite new technologies that allow more automation, workers still perform highly repetitive tasks and custom-fit construction materials together on site. When you begin to imagine construction in the context of modern manufacturing, you begin to see how construction can transform into production and subsequently, how the cost of building new homes begins to fall.
This idea is not as radical as it sounds. American department store Sears began selling prefabricated home kits in the early 1900s, and throughout the mid-century, various architects had their own little flings with prefab. The concept never truly caught on, but now, it’s beginning to get a closer look.
With an emphasis on material conservation and reuse, along with squeezing costs, architects, urbanists, and environmentalists alike are beginning to consider the benefits of prefabricated construction.
Estimates show construction project costs could be reduced by over one-third and completion schedules shortened by more than half, if developers made use of a prefabricated approach to construction. To boot, prefabrication significantly reduces the amount of waste sent to landfills. For example, compared to traditional stick-framing methods, PUReWall™, a panelized wall used in residential construction, generates 30 times less jobsite waste and takes only half the time to erect.
Slowly, this approach to building has begun to take hold, and today, city planners across the world are turning to prefabrication to solve cities’ affordable housing crisis, prevent unmanaged urban sprawl, and improve the living conditions of the urban poor.
In New York, more than a dozen prefabricated buildings have been constructed over the last few years, and the city’s most recent prefabrication project will offer apartments to low-income New Yorkers.
In developing megacities, prefabrication may offer the most impact: There is a market to serve 200 million slums in emerging countries, according to a report by McKinsey & Co.
India, for example, has a shortage of 18 million housing units, and as a result of the government’s push to make affordable housing a priority, a growing number of developers and private equity firms are entering the affordable housing market. Prefabrication technology could be a game changer in this movement, offering a solution to sustainably replace informal settlements with low-cost housing and improve the lives of millions of urban dwellers.
There are still many challenges to be addressed before an industrialized approach to housing becomes widely accepted, but the pieces of success, like many prefabricated elements, are coming together in a very promising way, at a time when our cities need new housing most.
If you think of today’s cityscapes, various materials come to mind: the glass and steel of an office park, the dignified brick of apartment buildings, the blacktop pavement, and the concrete jungle of 20th century urban renewal. But with cities’ construction increasingly moving from field to factory, developers are beginning to experiment with an innovative, age-old material: wood.
Although wood hasn’t been used to build much other than single-family homes since the horse-and-buggy era, the time-honored material is now experiencing a comeback. Seeking greener and more affordable projects, builders are choosing timber for apartments, offices, and university buildings, rather than the concrete and steel that have ruled the construction industry for decades.
Unlike the production of concrete and steel, which generates massive amounts of CO₂, the creation of lumber is a relatively low-pollution process. In addition, wood is a carbon sink. According to researchers at the University of Canterbury, construction of a mid-rise building made of steel or concrete results in emissions of roughly 1,600 metric tons of CO₂. By contrast, a similarly sized building constructed from engineered wood products has zero carbon footprint – and can even sequester up to 600 metric tons of CO₂.
The lumber used to construct today’s tall-wood structures bears little resemblance to the lumber you’d find lying around your grandfather’s workshop. Architects and builders now work with “mass timber,” a form of construction that uses large, prefabricated wood panels.
These panels, called “cross-laminated timber,” are made by using a bio-based resin to glue layers of solid-sawn lumber together in alternating grain orientations. This process enhances the stability of the product, allowing buildings to reach impressive heights.
In North America, cross-laminated timber has been used mostly for low structures, like two-story apartment buildings or offices and schools, but Toronto’s Brock Commons student residence house demonstrates how mass wood can be used for the masses. Thanks to prefabrication, the 18-story building was constructed in less than 70 days, and today, it houses over 400 students.
Mass timber is also spreading across Europe, Asia, and Australia, and if this growing chorus of architects and builders has their way, we might just begin to see more trees inside our concrete jungles.