Better buildings
July 27, 2021

There is life after demolition: Mass timber, circularity and designing for deconstruction

The first Shikinen Sengu was held in the year 690, in the city of Ise, Mie Prefecture, Japan. It consists of a set of ceremonies lasting up to eight 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.

CLT panel being installed.

1 Lonsdale Avenue (formerly PH1) construction | Photo credit: KK Law

By Eduardo Souza, ArchDaily

Every 20 years, a new divine palace with exactly 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 idea of creating a building that will have an expiration date is not a common one. In fact, the useful life of a structure is often given little consideration. When demolished, where will the materials go? Will they be disposed of in landfills or could they be reused in new projects? There are certain construction methods and materials that make this process easier. Others make reuse unfeasible, due to several factors.

Design for Deconstruction

Thinking about the building's end-of-life

The so-called design for deconstruction (known by the acronym DfD, or design for disassembly) 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 minimize 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. Architects and engineers can contribute to this movement by designing buildings that facilitate adaptation and renovation. Designing for deconstruction is designing so that these resources can be economically recovered and reused.” Taking the example of Canada, 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.

Photo credit: KK Law

PH1 construction prefabrication mass timber naturallywood
Extending the building's lifecycle

Recycle, reuse, remanufacture

An even broader concept is that of DfD/A, or design for disassembly and adaptability. It is a strategy that also 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.

Circular economy in the construction value chain. Image credit: Circular Economy & the Built Environment Sector in Canada

diagram naturally wood