“Use materials how they want to be used”

Philippe Block on how to “Produce Leaner”

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    NEST HiLo roof: Finalized concrete shell sprayed on the cable net and fabric formwork © Block Research Group, ETH Zurich / Photo by Stefan Liniger.

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    Philippe Block, Professor of Architecture & Structure, Institute for Technology in Architecture, D-ARCH, ETH Zurich; Member of the Academic Committee, Holcim Foundation for Sustainable Construction (2014–); and Member of the Board of Directors, Holcim Ltd, Switzerland. © Block Research Group, ETH Zurich / Photo by Juney Lee.

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    NEST HiLo roof: Construction of the cable net © Block Research Group, ETH Zurich / Photo by Juney Lee.

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    NEST HiLo roof: Installation of the fabric formwork © Block Research Group, ETH Zurich / Photo by Juney Lee.

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    Lessons on building leaner from the past: by analysing the structural geometry of Gothic cathedrals such as King’s College Chapel (fan vault constructed 1512-15), the Block Research Group is finding answers on how similar designs could be applied using low-strain, locally sourced materials. Photo © oversnap, iStock.

Philippe Block pushes boundaries. He calls into question the very postulates underlying design and what is currently considered feasible and desirable in construction. He urges all actors in the industry to “produce leaner” and move from a wasteful take-make-throw model to a circular take-make-repeat economy. This transition to circular construction can be achieved systematically by taking into consideration aspects including raw material consumption, environmental impact of a material over its lifecycle, as well as the structural geometry of building design.

Last updated: May 12, 2021 Zurich, Switzerland

“Architecture still hasn’t caught up with concerns surrounding the ecological impact of the construction sector – but options are increasing along each step of the design and construction chain that can enable a shift from linear production models towards more circular processes” Philippe explains. As a Professor at the Institute of Technology in Architecture at ETH Zurich, he leads the Block Research Group (BRG) and has earned numerous accolades globally. He is also a member of the Academic Committee of the LafargeHolcim Foundation for Sustainable Construction and a member of the Board of Directors of LafargeHolcim Ltd.

“The notion of producing leaner initially focused on building lighter”, he says, “but we now need to consider the environmental impacts of producing building materials as well as the overall principles of construction. People used to think that stronger materials were better because they enabled us to build thinner structures, but we’ve learnt that this is the wrong target. Stronger materials that have an enormous carbon footprint entirely miss the point due to their environmental cost.”

KingsCollegeChapel-iStock-138175865.jpgThat concern is what drives the BRG to re-examine the fundamentals of design: innovative structural geometry is what will enable the use of different construction materials, whether they be repurposed such as recycled aggregates from demolition waste, or newly engineered. By studying historical monuments such as Gothic cathedrals, and by analysing the structural geometry of their unreinforced masonry, the BRG, co-directed by Tom Van Mele, assesses how similar designs could be applied to low-strain, locally sourced materials. These may seem like “humble materials”, Philippe says, but they have a lower carbon footprint than more heavily engineered ones, and there is no reason why they should not give rise to “exciting and beautiful architecture.”

10_DSC04411_HiLo_construction_fabric-insta…“For too long, we’ve ignored what materials want to do.”

Reminding us that natural forms have no straight lines, Philippe points out that the way we currently build is contrary to the laws of nature. Rather than starting from an abstract shape that is “inherently detached” from its material context, the design process ought to be reversed: architects and engineers should first learn about non-polluting, re-cycled materials, before finding what interesting new shapes can emerge from their constraints. “We have ignored what materials actually want to do, how forces naturally want to flow to support, for too long.”

The HiLo prototype (high performance building through low embodied operational energy), a full-scale construction experiment led by the BRG on the campus of the Swiss Federal Laboratories for Materials Science & Technology (Empa), demonstrates how this can be achieved. The arched HiLo roof is made of a thin concrete shell sprayed over a cable net and fabric formwork designed with the help of computational tools. The form-finding methods developed by the BRG made it possible to design non-uniform weight distribution in the tensioned cable net.

“We were able to reduce the weight of the carbon plate floor by more than 50% compared to equivalent concrete floors, because we got the geometry of the roof right with a vault design. Thinking about the material’s natural strengths and constraints led us to use concrete only where it wants to be, which is in an arch for compression. By doing that, we were able to remove most of the reinforcement”, he explains. “If we treated the entire world like our HiLo floor plate, we could reduce the volume of concrete used globally by half. An even greater benefit would be the substantial reduction in steel reinforcements, which would massively reduce the raw material and energy demand of the structure.” With the amount of construction due to occur in the developing world over the coming years, such innovations could have profound effects.

07_DJI_0205_HiLo_construction_drone_Juney-…“I see an opportunity in the climate crisis.”

Philippe’s work spans architecture and structural engineering and incorporates design, structural geometry, computational form-finding, and materials science. While he is optimistic for the future of the industry and points out that many new materials and recycled components are already becoming available for commercial use, he also sounds a stark warning, saying that we have ten years to avert runaway climate change.

Learning from the Global South’s experience in adapting to multiple constraints might be helpful at a time when more creativity and responsibility are needed to meet the challenges ahead. With that in mind, he views governmental regulations and sustainability targets as welcome pressures on Western countries that have so far enjoyed the freedom to build without limitations. “I see an opportunity in the climate crisis and am hopeful that it will drive people to innovate”, Philippe says, reimagining the future architect as a new kind of ecologically and ethically minded master builder.

Listen to the 4-minute interview with Philippe Block

Digitalization, labour, and construction: Re-materializing Construction

As a thought leader on structural design, computational engineering and digital fabrication of concrete construction, Philippe Block moderated the LafargeHolcim Forum workshop on Digitalization, labour, and construction. He addressed the need for new disruptive technologies and for a multi-disciplinary response to enable digital design to contribute to more efficient construction methods – with more beautiful and sustainable outcomes.

More about the workshop – From manual to digital and vice versa: Digitalization, labor, and construction