Buildings are responsible for nearly 40% of global carbon emissions. When a building is demolished, it leaves behind a huge pile of trash. The continuous increase in construction projects around the world increases the amount of waste in landfills, which has a critical impact on the economy and the environment. What would it take to design a building for its lifetime and so that it could be deconstructed once its usefulness had passed?
An emerging group of architects, engineers, contractors and designers are determined to find a new way to build, some of which are chronicled in a recent New York Times article. With a common philosophical belief in a circular (also sometimes called regenerative, cradle-to-cradle or donut) economy, they believe that the ideal process for removing an old building would be to take it apart and reuse its parts.
Circularity emphasizes the composition of things rather than their use. In this way of thinking, anything done thoughtfully enough can last forever or offer its molecules to decay and rearrange.
The life cycle of a building can be divided into 5 different stages: design, production, construction, use and end of life. There are two main principles for considering life cycle as part of potential construction debris:
- First, on a planet with limited resources and a rapidly warming climate, it’s crazy to throw stuff away.
- Second, products must be designed with reuse in mind.
It’s the second principle that is less commonly accepted and more problematic – how can we get companies to reassess their business in the most basic way? Recycling built structures would require a complete rethink of what it means to plan infrastructure over much longer time scales. Given the compelling threats of global climate change, sustainable construction is the way forward for the building industry to play its part in achieving a sustainable and healthier world.
Creating a true circular building economy is, however, quite challenging.
The construction debris problem
Over the next 4 decades, built space comparable to the square footage of another New York City will be added to the planet every month. The use of construction and demolition waste resources is considered an important way to achieve sustainable development of the economy and the environment. Recasting waste in politics is complicated. In the circular system, everything is used. Instead of being thrown away, waste is collected in separate spaces where it is redone. In this futuristic landscape, building materials blend into the environments from which they originate.
The construction industry is one of the most environmentally damaging industries in the world. It directly impacts the use of raw materials, their determination of use involving the entire life cycle, and the surrounding environment. Current and common barriers to this reality are stark and include:
- standardized construction elements made of composite materials
- rigid supply chains
- fixed laws and contracts
Clearly, the transition from a linear to a circular economy in the building sector is still in its infancy.
This is because the materials have a very complex nature. Almost everything in our built environment is impregnated with chemicals derived from fossil fuels. As UPenn regards, for over 50 years the majority of building materials have been engineered using polymers with the aim of achieving a range of advanced performance capabilities. Polyvinyl chlorides are used in plumbing supplies, exterior siding, interior surfaces, furniture, and landscaping.
The petrochemical industry lobbied to shape local building codes and encourage architects and engineers to incorporate new composite materials into their designs. The result is that everything is encrusted with fibres, coatings and pigments that are essentially oil and gas derivatives, making it difficult to reuse. In most cases, it is more expensive to renovate than to build new.
A new paradigm of building materials
What kinds of business models are needed so that new and improved methods and innovative services can lead to a net reduction in resource use and the minimization of construction waste going to landfill? There are different possibilities regarding the after-life options of buildings: maintenance, renovation, demolition and deconstruction.
Proponents of circularity also say it’s not just about materials, but about how the overall economy is structured. Strategies such as organizing temporary trash cans in each construction zone and identifying construction activities that produce recyclable materials have high usability indices. The same goes for improving the company’s policies for recycling construction waste.
Researchers in Austria describe how deconstruction represents a sustainable alternative to communal demolition, which tends to be an “arbitrary and destructive process”. Rather than minimizing the effect of construction debris on the environment, they argue that the built environment can be seen as a key sector for the transition from linear to circular economy. The construction industry could:
- contribute to resource efficiency
- improve the use of energy during the life cycle of buildings
- incorporate better quality durable materials
- demand more waste recycling
- improve design features throughout a building’s life cycle
A building that is deconstructed rather than demolished
To be able to analyze the deconstructive potential of a building, it is necessary to know how its entire life cycle works. It starts from the origin: the concept of its construction, the local context, the choice and origin of the materials, the different types of environmental impacts that make up each phase of the life cycle.
This approach makes it possible to understand how each choice made in the design and production phase is then reflected in the use and disposal phase.
Then, deconstruction must be separated into two categories, explain the Austrian authors, according to the relationship to structural or non-structural elements.
- Structural deconstruction involves the dismantling of structural elements of the building that are an integral part of the building and contribute to its stability, such as beams and pillars for rigid frames and brick walls for load-bearing systems. It needs a range of tools and equipment, heightened safety considerations, and a lead time of days or weeks to complete. This is not always possible and depends on the construction technique — does it allow the connection between the elements in a reversible way or not?
- Non-structural deconstruction consists of the recovery of non-structural elements whose removal does not depend on the structural integrity of the building and which are generally easy to dismantle, such as doors, windows and finishing materials. In general, non-structural deconstruction can be accomplished relatively easily and with few tools, limited labor, and typical job site safety considerations, which typically last for hours or days. Building components can be removed without destructive approaches or additional structural support.
Final Thoughts on Deconstructing Buildings
Reusing building materials has been common since humans built homes. Today, the practice has ecological significance, with the reuse and recycling of building materials aimed at preserving virgin materials and keeping the level of climate pollution from construction and the use of construction artifacts low. .
With upcoming landfill bans and subsidies that support resource conservation, deconstruction of buildings will likely become a norm in society. This means that the associated costs will be integrated into the construction planning. The socio-economic benefits of deconstruction will accompany environmental benefits, including increased job opportunities, job training, historic preservation, availability of building materials, and small business development in economically disadvantaged areas.
A methodology for the entire planning process must include principles of deconstruction at each stage of the life cycle. Deconstruction will require connections between structural and non-structural elements as well as smart material choices that promote the use of reusable and eco-compatible materials and minimize the use of hazardous materials and compositions. This will require providing access to information regarding the construction and deconstruction of buildings, with instructions to be followed for the correct identification and dismantling of components and their possible reuse or recycling.
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