USB | Net-Zero Biochar Concrete house unit by ELEMENTAL and Holcim

To build or not to build? That is the question. The built environment faces a paradox: We must build billions of square meters to address the global housing crisis, yet conventional construction methods intensify environmental damage. To break this dilemma, ELEMENTAL and Holcim are collaborating on a full-scale prototype of a Basic Services Unit (USB) built with a net-zero concrete* mix using biochar technology, which acts as a carbon sink and supports decarbonization in construction.

The project rethinks incremental housing by reducing it to its essential core: a unit that provides fundamental services, such as a kitchen and bathroom, ensuring shelter and sanitation. Using precast panels and modular systems increases construction efficiency, shortens building time, and helps avoid unsafe, self-construction. The approach recognizes housing as an evolving process rather than a finished product – a verb instead of a noun.

*Scope of concrete production phases (A1-A3, cradle to gate) in Life Cycle Assessment.