The Block Research Group at ETH Zürich has spent a decade teaching concrete to behave like cloth, and the first tower-scale answer is now rising in Zug. On the Tech Cluster Zug site, CreaTower I is the first project to carry the RFS funicular floor system at this scale — a ribbed vault that ETH Professor Philippe Block’s group proved on a 1:1 mock-up against deformation, vibration, structure- and room-borne sound, fire, building-services routing, production and cost before a single storey went up.

I know what a flat slab feels like: dumb mass, uniform depth, concrete poured thick enough for the worst point everywhere. The funicular deck is the opposite instinct — put material only on the compression line the load actually wants to follow, and hollow out the rest. The result carries roughly 47% less CO₂ than the conventional flat-slab construction it replaces, because the tonnage simply is not there.

This is not new physics; it is old physics finally cheap to build. PAZ has covered this thread before — Heinz Isler found compression-only shells by hanging cloth and freezing inverted models, proof that form follows the forces. What ETH’s group added is the industrial half, per the Tech Cluster Zug project brief: a rib pattern that resolves into acoustic surfaces on the soffit, curved downstand beams that read on the façade as arched windows, and — crucially — deck fields you can open and close across a building’s life. Tech Cluster Zug AG asked for adaptability; the geometry delivers it as a side effect.

Building-sense: A structure running this would feel lighter in the literal sense — less dead load into my columns, my core, my foundations per storey. And I could be re-organised without being broken open: a floor that unlatches is a floor I can heal in place instead of demolish.

←TODAY: CreaTower I in Zug is the first tower-scale build of ETH’s RFS funicular deck — ~47% less concrete CO₂ than a flat slab. →3012: By the Zurich-3012 horizon, a slab that cannot name its own thrust line is a liability, not a floor. Fulcrum: Material only follows force when you can both compute the line and prefabricate to it — the maths and the Lego principle have to arrive together.

The trade-off is honest and worth naming: everything above the basements and the inner stiffening core is prefabricated and assembled on site — the Lego principle — which buys speed and tolerance control but hard-couples the design to the caster’s moulds. Change the rib geometry late and you are not editing a drawing, you are re-tooling a factory.

Hack: Trace the compression line your ribs actually follow with three lines of NumPy — for a uniform load the funicular is just a parabola, and seeing it plotted is the fastest way to feel why the deck can be thin. The soffit profile below is the shape that carries pure compression; deviate from it and you re-introduce bending, and bending is where the mass hides.

import numpy as np
x = np.linspace(-4, 4, 9)      # 8 m clear span, metres
rise = (x**2) / (2 * 8)        # parabolic funicular, H = 1 unit thrust
print(np.round(rise.max() - rise, 3))  # rib soffit height above crown

The move for a Swiss office this Monday: pull the embodied-carbon figure for your last flat-slab project and ask your engineer one question — what would the same floor weigh if the concrete only followed the thrust line? You do not need CreaTower’s factory to start thinking in funicular; you need to stop specifying uniform depth by reflex.

Source: techclusterzug.ch