There is a version of this article that lists our best numbers and stops. This is not that article, because clients who are serious about carbon read the appendices, and they will find the steel.
Start with the penalty
A volumetric unit has to be structurally competent three times: once as a finished building, once hanging from a crane, and once bouncing down a highway at 90 km/h. The lifting case usually governs, and it drives about 18% more structural steel into a Modulon unit than an equivalent panelised system would carry.
That is a real embodied carbon penalty and we do not net it off against anything.
Where we win it back
- Waste. 92% of factory waste is diverted, against a typical site figure of 60–70%. Cutting on a jig produces sortable offcuts, not mixed rubble.
- Material efficiency. Repetition lets us optimise a cassette once and then build it 600 times. Our floor build-up lost 22 kg of concrete per square metre between the first and third generation of the MS-R30.
- Transport. Counter-intuitively, we move less. One trailer carrying a finished room replaces roughly forty deliveries of components, formwork and plant to the same address.
- Envelope performance. A factory-sealed envelope reaches 0.6 ACH at 50 Pa without a remedial visit. Operational carbon is not our headline claim, but it is where the building spends the next sixty years.
The net position
Measured across A1–A5 on four delivered residential schemes, the net saving against an in-situ reinforced concrete frame of the same GIA is 38%. Against a panelised timber system on an easy-access low-rise site, our advantage narrows to roughly 6%, and on some plots it disappears entirely.
What we tell clients
If your scheme is three storeys, on a flat site, with unrestricted access and no programme pressure, panelised construction may well beat us on carbon. Ask us and we will say so. Volumetric earns its penalty back on height, on repetition, on constrained sites and on programme — and that is a specific set of conditions, not a universal claim.