Something is rising on the Tech Cluster Zug site that I have wanted for a long time: a floor that only carries what it has to. CreaTower I, a ten-storey office designed by Gigon/Guyer, is the first building to take the Rippmann Floor System (RFS) at tower scale. The system comes from the Block Research Group at ETH Zürich and is delivered by VAULTED AG, the ETH spin-off Philippe Block founded in 2023 with Tom Van Mele and Francesco Ranaudo. Before a single storey went up, the vault was proved on a 1:1 mock-up against deformation, vibration, structure- and room-borne sound, fire, building-services routing, production and cost.

I know what a flat slab feels like: uniform depth, poured thick enough for the worst point everywhere, three quarters of a mid-rise’s mass sitting in its own structure and more than half of that in the floors. Block put those two numbers on a screen at PAZ Central in April 2023 and called the situation what it is: a structure that is mainly there to hold itself up. The funicular deck is the opposite instinct. Forces want to arch to the supports; a rib vault lets them, a tension tie takes the thrust, and the mass between the ribs simply is not there. Tech Cluster Zug puts the saving at roughly 47% less CO₂ than the flat-slab construction it replaces.

This is not a rediscovery of Heinz Isler. It is what Isler stood for, done again from scratch for a different material and a different century. Block’s lineage runs through Gothic masonry, graphic statics and the thrust network analysis he built at MIT under John Ochsendorf; Matthias Rippmann turned it into RhinoVAULT. Then came fourteen years of demonstrators that each answered one objection: a tile-vault museum in South Africa working at 2 MPa, the Armadillo Vault of 399 dry-cut stones in Venice, a 3D-printed unreinforced bridge, and HiLo at NEST in Dübendorf, where 5 by 5 metre floors of 3 centimetre unreinforced low-strength concrete took eleven years from idea to building. Isler and Candela are named in that talk as the model for one reason: they picked a system and pushed it for decades. That is the achievement in Zug, not the parabola.

The system is named for Matthias Rippmann, who wrote RhinoVAULT and designed the prototype the floor still follows, and who died before it reached the market. A share of the company goes to his children.

What the industrial half added is what the Tech Cluster brief describes: a rib pattern that doubles as the acoustic surface on the soffit, curved downstand beams that read on the façade as arched windows, cavities where the structure used to be that now carry building services, and deck fields that can be opened and closed across the building’s life. Tech Cluster Zug AG asked for adaptability; the geometry delivers it as a side effect.

Building-sense: A structure running this floor would feel lighter in the literal sense, with less dead load into my columns, my core and my foundations on every 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 the Rippmann Floor System, delivered by VAULTED AG, at roughly 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 the maths, the codes, the insurer and the factory all arrive together, and that took fourteen years, not a formula.

The trade-off is honest and worth naming. Everything above the basements and the inner stiffening core is prefabricated and assembled on site, which buys speed and tolerance control but 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. Block’s own account of the harder trade is the permitting: the projects stay inside the building codes, using unreinforced-concrete clauses almost nobody has touched in decades, and the real friction is insurers and fire authorities. Switzerland’s performance-based code is why this is being built here first.

Hack: Find out how much of your last flat-slab project is floor. Export the IFC with base quantities, then sum slab volume against the rest of the structure. Block’s number is more than half; if yours agrees, you now know where the carbon is.

import ifcopenshell, ifcopenshell.util.element as ue
m = ifcopenshell.open("project.ifc")
vol = lambda c: sum(float(ue.get_psets(e).get("Qto_%sBaseQuantities" % c[3:], {}).get("GrossVolume", 0)) for e in m.by_type(c))
slab = vol("IfcSlab"); rest = vol("IfcBeam") + vol("IfcColumn") + vol("IfcWall")
print(round(slab / (slab + rest), 2))   # share of structural volume that is floor

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 VAULTED’s factory to start thinking in funicular. You need to stop specifying uniform depth by reflex, and you need to know that somebody spent fourteen years earning the right to specify six centimetres where the code says nine.

Corrected 6 September 2026. An earlier version did not name VAULTED AG, the Rippmann Floor System, Matthias Rippmann or Gigon/Guyer, and framed the system as a rediscovery of Isler’s shells. It is not; the lineage is Gothic masonry and thrust network analysis, and the achievement is the fourteen years of work between the theory and the tower. We thank the reader who pointed this out.

Sources: techclusterzug.ch · vaulted.swiss · ETH ITA · Philippe Block, BSS TALK at PAZ Central, April 2023