Marasse covers Canada, the United States and Mexico for a Belgian family company whose board is five Reynaers siblings and five outsiders, and whose owners expect their grandchildren to run it. That second fact is the one he built his case on. The market he covers is not one market: Vancouver pushes operational carbon and passive house, Miami wants hurricane rating and impact resistance, Winnipeg reaches minus fifty and therefore wants modular prefabrication because the building has two months to close, and the southwest wants ultra-minimal sightlines.

Then Calgary, where he was told plainly that he could talk about sustainability but nobody here cares. He accepted the economics of that, and that sustainability will only happen at scale once it is regulated, but not the conclusion. His own reason is nearly eight years old, and the argument is simply that whoever inherits this should get what we got.

The scale is not in dispute. Buildings use half the world’s resources, create 35 per cent of all waste, produce 39 per cent of all carbon dioxide and consume half of all energy, and roughly 80 per cent of North American building stock is energy inefficient. That drives two revolutions at once, circularity and renovation, which is the embodied against operational carbon argument. His warning was against taking one side of it. A fibreglass window is arguably the best cold-climate answer there is, no thermal bridging, excellent for operational carbon, and non-recyclable. If all these green windows on all these green buildings are destined for landfill, he asked, how sustainable is that?

Nor is the obvious fix available. Add recycled aluminium and you decarbonise instantly, except that only about 36 per cent of global demand can be met from recycled content, so the rest still comes from primary extrusion. A manufacturer can advertise 90 per cent recycled content, but monopolising a finite supply only pushes somebody else’s number up. It is a zero-sum game.

What is left is unglamorous. Eco-design means attention to weight and material: wall thicknesses optimised to the loads a system will actually see, fittings and fasteners reused across systems, and aluminium half-shells and thermal strips recombined so different systems come out of the same components. Designing for disassembly and reuse means the BCIT tall timber student housing in Vancouver, where a modular prefabricated system built in a workshop followed the mass timber in lock step so the timber never stood in the rain. And designing for extreme weather is now ordinary work: the big North American demand is Miami-Dade certification and Florida wind zone 3, which covers essentially the whole south and east coast.

On materials he gave numbers rather than adjectives. Aluminium is among the most circular materials there is: an average life beyond fifty years, 75 per cent of all aluminium ever made still in circulation, 95 per cent of it recycled. Their mix averages around half recycled content, which he does not think solves anything, so the harder target is lower primary carbon: 3.31 kg of carbon dioxide per kilogram now, against a global average of 5.2 and a European average of 10.48, with 2.81 committed by 2030 under a science-based target. More than 70 per cent of the thermal break material is low carbon, recycled or recyclable, and there are tools to calculate a specific project’s embodied carbon from its actual product mix.

Traceability was the part he seemed least comfortable about. The industry has long been able to follow aluminium from the London Metal Exchange to the installed wall, and nothing before that: where the bauxite came from, who mined it, whether it was mined by slaves. Hence membership of the Aluminium Stewardship Initiative, which is building visibility across the chain from extraction to recycling, human rights included. Ask for the EPDs, he said; sustainability no longer has to be adjudicated on gut feel, and a digital product passport now carries the same traceability to the end user.

He closed on the curve. The Paris agreement of 2015 set decarbonisation by 2030 and net zero before 2050, and because governments could not deliver it alone the science-based targets initiative built a voluntary corporate framework alongside. Against its expected 590 kg of carbon dioxide per square metre, his own life-cycle analysis sits roughly on target. Set that against analyses from the University of Toronto and Canadian real estate bodies, though, and the best concrete and timber buildings now available only reach about 2030 on that scale. After that, he said, there are not many solutions yet.