Building materials giant Holcim has partnered with Chilean architect Alejandro Aravena’s firm Elemental to present a pioneering carbon sink technology at the 2025 Architecture Biennale in Venice. Their goal is to make buildings part of the climate solution.
The new technology, which integrates biochar into cement, mortars and concrete, enables structures to permanently sequester carbon dioxide that would otherwise be released into the atmosphere.
It is being demonstrated in a full-scale prototype of a Basic Services Unit – a modular housing concept that provides core living infrastructure while allowing residents to expand their homes over time.
“Holcim is the leading partner for sustainable construction,” said CEO Miljan Gutovic. “Through our partnership with Alejandro Aravena and the Elemental team, we have demonstrated how Holcim’s new carbon sink technology can shape the future of construction.”
The prototype will be featured in the Time Space Existence exhibition, which is organized by the European Cultural Centre and runs from May 7 to Nov. 23, 2025.
Biochar Innovation Turns Buildings into Carbon Sinks
At the heart of the innovation is biochar, a charcoal-like material made by heating organic waste in a low-oxygen environment.
Holcim said that when added to low-carbon concrete formulations, it can capture and store up to three kilograms of CO2 per kilogram of biochar.
The mix also uses 100 percent recycled aggregates, reinforcing the company’s push for circular construction.
Aravena, a 2016 Pritzker Architecture Prize laureate, said the technology aligns with his vision of addressing housing needs at scale and speed while minimizing environmental impact.
“In Venice, we are bringing incremental housing to its core: a structural sanitation unit using precast panels takes care of the basic needs of inhabitation,” Aravena said.
“Holcim’s new decarbonization technology allows us to address the scale and speed of the housing crisis’ demand without putting a strain on the environment.”
The carbon sink solution expands Holcim’s portfolio of sustainable offerings, which includes Ecopact and Ecoplanet low-carbon building materials and its Ecocycle circular construction technology.
While Ecopact and Ecoplanet deliver at least 30 percent lower carbon emissions than standard concrete production, Ecocycle is a technology platform that recycles up to 100 percent of construction and demolition materials.
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