Eric Claeys explored steel and hybrid curtain-wall strategies for projects where slender sightlines, fire, structure, scale or bespoke geometry push conventional aluminium systems beyond their comfortable range.
Eric Claeys challenged the assumption that aluminium should remain the automatic answer for every curtain wall. His case for hybrid steel systems was deliberately provocative: where strength, fire performance, section depth, logistics or long service life dominate the brief, the material logic can change. The proposal is not simply a steel copy of a conventional stick wall. It combines ideas from stick and unitised construction, using a permanent grid that can accept replaceable infill and external shading while trying to reduce transport, fabrication and installation demands.
Material choice should follow the governing constraint
Claeys started from structural and building-physics requirements rather than from a preferred system type. Steel’s higher stiffness and strength can make slender profiles possible where aluminium would need greater depth or more material. Stainless or galvanised variants can be selected for different exposures, while fire resistance and seismic capacity were presented as additional areas where steel can broaden the performance range. He also argued that fabrication need not inherit the heavy welded image associated with traditional steel façades. The hybrid system is designed around precision machining and assembly without relying on welding for the primary curtain-wall grid, making repeatable manufacture central to the concept.
Hybrid means borrowing from two delivery models
Conventional stick construction can be flexible but demands substantial site labour and weather exposure. Unitised façades move work into the factory but bring transport volume, storage, pre-financing and replacement complexity. Claeys’ hybrid proposition keeps a site-installed grid while simplifying infill and external cladding so more work can be carried out safely from inside. The commercial argument is as important as the technical one. Shorter lead times, lighter logistics and less dependence on scaffolding or mast climbers were all presented as ways to reduce cost and programme risk rather than treating innovation as a premium feature.
Embodied carbon is only one part of façade sustainability
Claeys claimed a very large embodied-carbon advantage for steel profiles over aluminium in his system, but then warned against allowing that comparison to dominate the environmental discussion. His larger target was operational energy. A glazed façade that admits excessive solar gain can drive cooling demand for decades, overwhelming small product-level savings. That is why external shading was treated as part of the system. Claeys argued that keeping direct sun out can materially reduce cooling capacity, so a “smart” façade should use its structure to support shading, photovoltaics or other external layers rather than treating the curtain wall as a sealed glass plane.
The best circular grid may be the one that stays
His circularity argument focused on longevity. Instead of designing the complete façade as a disposable package, the primary grid should be capable of remaining for 40 or 50 years while infill panels, glazing and external technologies change around it. That separates long-life structure from shorter-life performance components. For renovation, the logic is powerful: if the grid can absorb slab movement and accept new infill, future upgrades may avoid replacing the whole envelope. Claeys described that flexibility as more meaningful than recycling a complete façade after premature removal.
Common sense remains the test
The talk repeatedly returned to first principles: control solar gain, choose the material that solves the structural problem, make installation safe, and avoid throwing away parts that can outlast a single refurbishment cycle. Those claims still need project-by-project verification, particularly where steel, aluminium, glass and coatings meet. But the useful provocation is to stop treating system type as fixed before the performance problem is understood. The hybrid proposition also depends on replaceability. Claeys separated the long-life supporting grid from shorter-life glazing and infill, arguing that the next renovation should be able to improve thermal, solar or smart-glass performance without discarding the primary frame. That demands accessible fixings and interfaces that can tolerate future products whose exact dimensions are not yet known. The claim for steel is strongest where its structural capacity supports that adaptable skeleton; it still has to be tested against corrosion protection, thermal bridging and project-specific fire requirements rather than assumed to win by material identity alone.
