Open Source · Closed Loop

We're building the open operating system for circular construction — and proving it with every building we own.

Once a bank can assess a component's residual value as reliably as it assesses land, circular construction becomes financeable. We're building the open stack and the bankable standard for that — and our own buildings, where we prove it ourselves first.

Why
Buildings as Material Banks

A building doesn’t lose its economic value all at once — it loses it component by component, every time something is installed in a way that can only be demolished later, never released again. At the end of a building’s life there’s usually a demolition crew, not value. Deconstruction costs money instead of returning it.

That can be reversed — not through persuasion, but by making material bankable. Once a component’s residual value is as reliably assessable as that of a plot of land, circular construction becomes the default instead of the exception. Components become assets with documented value, not debris with disposal costs.

That’s why we don’t just build the open stack — we build and hold our own buildings too: proof before claims. What holds up there becomes a stack module — what doesn’t gets cut from the model before anyone else adopts it.

Success for us doesn't mean being right — it means others adopting our model.

How

How we calculate viability

Circular construction has to hold up economically, not just ecologically. Whether it does isn’t decided by any single project, but by whether four theses hold at the same time — and reinforce each other rather than just adding up. We deliberately show what isn’t proven yet, too: that’s what separates a business case from a pitch.

01 Material value is bankable on the balance sheet (root thesis): an independent auditor has confirmed the residual-value approach (§253 HGB) as methodologically sound and attestable. Without it, theses 2 and 3 collapse. The independent attestation itself is still pending
02 Extra cost falls toward zero through digitalization — the model’s biggest return lever, and its least proven: no completed reference project confirms this yet
03 The financing advantage exceeds the extra cost — banks reward the certified material value as extra security through better rates or loan-to-value, not committed yet today
04 Acid test: does the advantage hold up during the hold period even if a buyer doesn’t pay extra for it at exit? Only then does the case stand on its own

A simplified example, for illustration only

Three advantages can already be quantified today — some independent of bank or buyer, some even when a buyer doesn’t reward the material value at exit at all (acid test, thesis 4):

Return on equity (IRR), circular vs. linear twin

up to +2 pp

Even without recognition by a buyer at exit (acid test, thesis 4)
Cash-on-cash return, circular vs. linear twin

up to +1 pp

Higher ongoing liquidity per euro of equity invested
Planning time via rule-based construction

up to -25%

Works purely through our own execution — independent of bank or accounting
Important note

Model calculation with documented but not yet externally validated assumptions — not a real project, not validated market data, not investment or tax advice.

What

Three ways to meet us

For developers & manufacturers
Stack

The open standard and reference implementation.

View →

For banks & surveyors
Seal

The bankable certification standard.

View →

For founders & talent
Blueprint

How to build a circular construction company as an open-source organization.

View →

Journal What's happening right now