by Yetsuh Frank, Managing Director, Strategy & Programs, Building Energy Exchange
Originally published in Building Energy Exchange Quarterly Report (Q1 2021)

The title here is an iconic quote by the legendary Architect, Louis Kahn.*  His answer, that the brick wants to be an arch, was an entreaty for the rational use of materials in construction.  Bricks set in an arch hold themselves in place without any hidden steel lintels or other structural gymnastics.  For a certain set of late-20^th century modernists, structural authenticity was close to a religious calling.  Hiding, obscuring–or worst of all, faking–the bones of a building was not just a missed aesthetic opportunity but a kind of moral and ethical failure.  Although this is probably no longer a view widely shared among Architects, we are seeing a revival of a similar attention to the basic essence of the materials we use to construct things: a desire to fully understand the impact of materials on our ecosystem, our own health, and most especially their contribution to the climate crisis.

It is easy to understand that a structure made of rammed earth–in which one simply digs up soil on the site and packs it down to create walls–uses far less energy in its construction than one made with steel, which requires first mining the raw ore, shipping that to a steel fabrication plant, melting and mixing the materials in a furnace, melting and shaping the castings in another furnace, sometimes shipping the castings to another plant, shaping the castings into wide-flange beams and other components, and finally shipping those to a construction site.  But what about the broad spectrum of materials that fall between these extremes?  And what about impacts beyond the carbon emissions that result from the manufacturing of various materials–the so-called embodied carbon?  As we add issues like toxicity, the depletion of finite resources, land consumption, and waste, these questions become increasingly complex.

Perhaps the simplest strategy for reducing the impact of materials is to avoid building new buildings. As our recent guest on Radio BE-Ex, Carl Elefante, has said, “the greenest building is the one that has already been built.”  This attitude may have found its ultimate expression in the work of Parisian architects Anne Lacaton and Jean-Phillippe Vassal, who this year have been awarded the highly prestigious Pritzker Prize largely due to their commitment to “never demolish.”  This reverence for existing structures leads them to propose, in the words of the Pritzker announcement, “restrained interventions” that not only reduce the waste of materials but preserve social capital.  Rather than desiring a blank slate, Anne Lacaton asserts, “Transformation is the opportunity of doing more and better with what is already existing. The demolishing is a decision of easiness and short term. It is a waste of many things—a waste of energy, a waste of material, and a waste of history. Moreover, it has a very negative social impact. For us, it is an act of violence.”  In a profession whose fees are often set as a percentage of construction cost, it is hard to imagine this unique perspective has not had a negative impact on their finances.  But their commitment is clear, especially with regard to social housing, where they have taken public stances against the demolition of projects and worked diligently with the building occupants themselves to understand their needs and design responses that meet them.  As the Chair of the Pritzker Architecture Prize Jury Alejandro Aravena put it, “Lacaton and Vassal are radical in their delicacy and bold through their subtleness . . . ”

When new structures are needed, we should prioritize materials whose impacts are as limited as possible.  Mass timber, for instance, offers significant reductions in embodied carbon over concrete and steel superstructures–when sourced from properly managed forests of the correct species.  There is renewed urgency around replacing petroleum-based materials like foam insulation boards with insulation fabricated from mineral wool and wood fiber.  There is even greater urgency around reducing the use of spray-foam materials that are produced using fossil fuels and also deliver an astonishing level of toxicity during both production and application.  Embodied carbon has often taken a back seat to operational carbon, but as the deadlines to avoid the worst impacts of climate change bear down on us, the carbon produced trying to build our way out of the problem grows in importance.

Fortunately there is evidence that this thinking is taking root at the Federal level, with the Green Building Advisory Committee recently recommending that the General Services Administration shift their massively influential procurement principles to prioritize low-embodied carbon materials.  A group of sustainable design leaders convened by the folks at Building Green recently submitted a package of recommendations urging the Biden administration to improve sustainability standards for Federal buildings.  The 10-page memo included a significant emphasis on measuring and accounting for the embodied carbon of materials.  In an upcoming Radio BE-Ex episode, we will be talking with Architect Stas Zakrzewski about designing buildings that target two key metrics–low embodied carbon materials and the Passive House standard.  But this will be one of many programs on the impacts of materials in the coming months, and of course many others in our community will be following suit.  Perhaps we are finally moving into a space where we think as deeply about the nature of materials as Louis Kahn did when he asked brick what it wanted to be.  When we consider the critical imperative to reduce the impact of construction, maybe the answer is that the brick wants to remain a brick.

* One of the finest and most revered Architects of the 20^th century, Kahn also had deep personal flaws.  In addition to his wife, Esther Kahn, Kahn maintained relationships with two women that were also at one time his employees, Harriet Pattison and Anne Tyng, and fathered children with all of them. Some of this triple life is described by his son, Nathaniel Kahn, in his 2003 documentary about his father, My Architect – A Son’s Journey.  An even broader perspective is provided by Wendy Lesser in her 2017 biography of Kahn, You Say to Brick.