By Tarren Bolton

The idea of creating a building that will have an expiration date is not a common one, but deconstruction – the reuse of existing structural components to create new facilities – is an age-old concept essential for creating a sustainable environment.

Design for Deconstruction (or Design for Disassembly, and even ‘construction in reverse’) is an important part of green design and a consideration of the complete life cycle of a structure. It includes provisions for the re-use of building components at the end of a structure’s life.

The ultimate goal of Design for Deconstruction (DfD) is to responsibly manage building materials to minimise consumption of new raw materials by using existing materials from demolished sites and finding ways to reuse them in another construction project.

An enormous amount of waste is produced in the demolition of building structures in most countries, which can be reused through reprocessing or re-manufacturing of materials, thus reducing the input of new resources and giving a new life cycle to the materials. DfD considers how all decisions made in the design phase can increase the chances of reusing the building parts at the end of their useful life. As defined in the EPA (United States Environmental Protection Agency) manual, “the ultimate goal of the Design for Deconstruction (DfD) movement is to responsibly manage end-of-life building materials to minimise the consumption of raw materials. By capturing materials removed during the renovation or demolition of buildings and finding ways to reuse them in another building project or recycle them into a new product, the overall environmental impact of end-of-life building materials can be reduced.

The challenges

Designing for disassembly requires a mindset that requires professionals to rethink the way buildings are put together so that the materials can be disassembled and reused, maintaining both their resource and carbon value. Image by Cortesia de naturallywood.com

Designing for disassembly requires a mindset that requires professionals to rethink the way buildings are put together so that the materials can be disassembled and reused, maintaining both their resource and carbon value. Image Cortesia de naturallywood.com

Though deconstruction is a very environmentally friendly and sustainable practice, it faces several challenges over conventional demolition. Many existing buildings aren’t designed for dismantling or disassembling, so the tools for deconstructing existing buildings don’t exist, and neither is the recertification of used components possible. Most construction companies operate under a tight profit margin and generally are not willing to jeopardise their profit margin by implementing reused programmes or expanding their demolition practices to deconstruct; they feel that it is simply not worth the financial risk to be environmentally friendly. However, the use of salvaged materials can be both beneficial and detrimental depending on the material’s durability, desirability, and longevity. The challenges can be easily overcome if there are changes in design and policy.

For architects, DfD is a difficult concept, as they conceptualise their buildings as being timeless and no architect wants to spend intensive labour creating a building only to have it torn down. The main problem faced today to practice deconstruction is that architects or builders of the past designed their creations to exist forever and did not make the necessary provisions for disassembling in the future. Even today, materials are not produced keeping recycling in mind. Moreover, even though architects want to design sustainable buildings that can later be reused for other purposes, the clients don’t want to opt for new building techniques as they are accustomed to and prefer traditional techniques. But architects can contribute to the environment by designing buildings that facilitate adaptation and renovation.

Buildings designed for deconstruction

About 25 % of demolition waste can be reused, while 70% can be recycled. There are certain construction methods and materials that make this process easier.

Buildings that have been designed with deconstruction in mind are often easier to maintain and adapt to new uses. Saving the shell of a building or adapting interior spaces to meet new needs ensures that new structures have a small environmental impact. The current trend in sustainable architecture involves the use of high-grade durable material.

Architects and engineers can contribute to the DfD movement by designing buildings that facilitate adaptation and renovation. Using Canada as an example, buildings are the largest consumers of raw materials and energy and the biggest contributors to the waste stream by weight, which equates to 3.4 million tons of building materials sent to landfills annually, representing an estimated 1.8 million tons of incorporated carbon.

DfD is a strategy that seeks to extend the life cycle of buildings and their components, allowing the building to be updated, maintained, and modified more easily; but, at the end of its useful life, disassembly still allows for the more efficient collection and reuse of materials and components. Managing the return and recovery of products and materials from companies, demolition sites, and material recovery facilities back into the value chain is the role of reverse logistics – a fundamental principle of the circular economy that allows product materials to be recycled, reused, and remanufactured.

DfD attempts to ensure that after dismantling, the materials have a known and well-considered destination. This can generate a number of benefits, including reducing waste and greenhouse gas emissions in buildings; improving the resilience of supply chains in construction; creating new economic, and employment opportunities, providing social benefits, and improving natural ecosystems through lower resource consumption.

The theoretical model works very well. But in practice, things are a lot more complex. Demolitions are usually carried out quickly, making it impossible to reuse a large part of the materials. First, it is essential to address the proper disassembly and separation of the parts that make up the building. But it is also essential that the project, from the beginning, seeks methods and solutions that reduce or eliminate waste, including products that are easily detached and disassembled as well as good quality materials that allow reuse and avoid harmful and polluting chemicals.

Mass timber as a Design for Deconstruction strategy

Mass timber components for this project were prefabricated offsite which not only aids in the ability for on-site assembly but also aids in the disassembly of projects in the future if needed. Timber's versatility allows it to be disassembled and then reassembled into other buildings and furnishings, sequestering carbon for longer so long as it stays out of the landfill. Image by Cortesia de naturallywood.com

Mass timber components for this project were prefabricated offsite which not only aids in the ability for on-site assembly but also aids in the disassembly of projects in the future if needed. Timber’s versatility allows it to be disassembled and then reassembled into other buildings and furnishings, sequestering carbon for longer so long as it stays out of the landfill. Image by Cortesia de naturallywood.com

The decision to choose a material or construction system, naturally, will not depend only on the requirements of disassembly. To aid in this selection, the life cycle assessment is a common method that helps shed light on the impacts of a product or process, from the beginning of the process (extraction of raw material) to the end of the process (reuse, recycling, or disposal).

According to the Circular Economy & the Built Environment Sector in Canada, using wood products – specifically mass timber (glue-laminated timber and cross-laminated timber) can reduce the building’s carbon footprint in several ways:

First, wood is a renewable resource, and its growth takes place through photosynthesis and not through mining or extraction. Trees grow in almost all climates and using local species can greatly reduce the amount of energy expended on transport. When a tree is harvested to make lumber and engineered wood, it stores carbon in the building. When another tree is planted in its place, it will also absorb and store carbon. Finally, because wood is versatile and durable, it can be disassembled and then reassembled into other buildings or other wood fibre products, sequestering the carbon even longer as long as it stays out of landfills.

And, of course, as with every industry today, technology also plays its part. A report by Delphi Group and Scius Advisory points out that, together with greater awareness of building materials and their impacts, growing trends in digital technologies have allowed for a circular economy in the built environment through greater productivity, efficiency, process improvements, and enhanced collaboration. Examples include BIM software, virtual reality (VR), drone technologies and new digital tools that improve tracking of material flows.

The junction between technology and ancient techniques, between recently created concepts and observations of nature, seem to be the best way to a sustainable future and a reconciliation with nature, of which human beings are a part and in which we are active agents of change. This includes understanding the materials and processes that make up the entire life of the construction, which will help us make more coherent and correct decisions guided by sustainability and responsible design.

Manufacturing cross-laminated timber, a mass timber product. Image by Cortesia de naturallywood.com

Manufacturing cross-laminated timber, a mass timber product. Image by Cortesia de naturallywood.com

Design for Deconstruction: A concept steeped in history

Ise Grand Shrine’s buildings are constructed in what is known as the yuitsu-shinmei-zukuri style, a type of architecture that incorporates building elements common in Japan before Buddhism was introduced to the country via the Silk Road. Image by Creative Commons

Ise Grand Shrine’s buildings are constructed in what is known as the yuitsu-shinmei-zukuri style, a type of architecture that incorporates building elements common in Japan before Buddhism was introduced to the country via the Silk Road. Image by Creative Commons

At the core of the Japanese Shikinen Sengu ceremony is the ritual of re-building two parts of the Jingu Shrine, Naiku (the inner shrine) and Geku (the outer shrine) which are both constructed almost exclusively from Japanese cypress.

The first Shikinen Sengu (shrine reconstruction ceremony) was held in the year 690, in the city of Ise, Mie Prefecture, Japan. It consists of a set of ceremonies lasting up to 8 years, beginning with the ritual of cutting down trees for the construction of the new Ise Shrine and concluding with the moving of the sacred mirror (a symbol of Amaterasu-Omikami) to the new shrine by Jingu priests.

Every 20 years, a new divine palace with the same dimensions as the current one is built on a lot adjacent to the main sanctuary. Shikinen Sengu is linked to the Shinto belief in the periodic death and renewal of the universe, while being a way of passing on the ancient wood construction techniques from generation to generation.

The grand shrine requires about 8 500 cubic metres of wood, and in 1922 a 200-year tree planting project was begun at Ise. The first wood from this programme was used in the 62nd renewal of the shrine, completed in 2014. Wood from the old shrine is recycled to help renew other, lesser shrines: the last time this was done some 169 shrines benefitted from the recycled wood.

References:

Souza, Eduardo. “There is Life After Demolition: Mass Timber, Circularity and Designing for Deconstruction” [Há vida após a demolição: madeira engenheirada, circularidade e projeto para a desconstrução] 27 Jul 2021. ArchDaily. Accessed 26 Aug 2021. <https://www.archdaily.com/963070/we-must-think-about-the-future-of-buildings-after-demolition-mass-timber-circularity-and-designing-for-deconstruction> ISSN 0719-8884.

Rethinking the Future (RTF): https://www.re-thinkingthefuture.com/rtf-fresh-perspectives/a973-designing-for-deconstruction/.