The Basic Services Unit (USB) combines principles of incremental design from Pritzker Prize-winner Alejandro Aravena and ELEMENTAL, with Holcim’s bespoke net-zero biochar concrete* with 100% recycled aggregates. This latest iteration transforms the home into a carbon sink and distils the concept into a 21 sqm unit arranged over two levels, integrating plumbing for a kitchen sink on the ground floor and a bath, basin and toilet upstairs. This core can be rapidly assembled using modular precast panels and can be expanded over time to a more generous home. Its adaptability can allow governments and relief agencies to deploy it following natural and man-made disasters, ensuring timely provision of decent, permanent and flexible homes. Biochar in the concrete mix was produced by converting waste organic matter through pyrolysis (thermal decomposition in an oxygen-free environment), sequestering the CO₂ that would otherwise be released. 1kg of biochar can prevent the release of up to 3kg of CO₂. In this instance, the concrete mix uses biochar as a substitute for sand. As the construction industry accounts for roughly 40% of global carbon emissions, integrating the biochar technology into construction, as demonstrated by Holcim and ELEMENTAL, could have a significant and lasting impact. *Scope of concrete production phases (A1-A3 cradle to gate) in Life Cycle Assessment. Assumes average transportation distance of 300km for cement and filler & 100km for aggregates.