Can we design structural systems that serve as long-term carbon stores?

Buildings account for nearly 40% of global carbon emissions, with embodied carbon representing an increasingly critical challenge. The majority of embodied emissions are concentrated at the start of a building’s lifetime—locked in before the building is ever used. This urgency drove ARPA-E to launch the HESTIA program, which aims to transform buildings into net carbon storage structures by developing materials and whole-building designs that are carbon negative on a life-cycle basis.

Our research brought together expertise in structural engineering, materials science, building systems, and life cycle assessment to develop and validate an innovative 3D-printed concrete floor system designed to achieve carbon negativity over its lifecycle. The project combined funicular structural optimization with carbon-absorbing concrete formulations, robotic prefabrication, and enhanced thermal performance—all requiring sophisticated integration to demonstrate verifiable carbon reductions at the whole-building scale.

Working with the research teams from the University of Pennsylvania, Texas A&M, and City College of New York, we developed comprehensive life cycle assessment (LCA) workflows that evaluated the combined carbon impacts of multiple innovations. These included geometry optimizations based on funicular forms with triply-periodic minimal surfaces (TPMS) for stiffness—innovations only possible with 3D-printing. The concrete mix incorporated carbon-absorbing biomineral additives that yield 42% higher CO₂ uptake than conventional concrete. Off-site robotic prefabrication eliminated formwork waste while enabling precise integration of post-tensioning systems with nearly 80% less reinforcement than conventional methods. Enhanced thermal mass coupled with adaptive setpoints and mixed-mode ventilation reduced HVAC energy consumption by 40-70%, with life cycle operational carbon savings of 12-33% across four climate zones. We created custom digital workflows linking BIM geometry, energy modeling, and parametric LCA to track emissions across every stage—from mineral extraction through 100 years of building operation and eventual end-of-life.

Our comparative screening studies demonstrated 60-70% lifecycle embodied carbon reductions compared to conventional reinforced concrete, while preliminary techno-economic analysis identified 10-40% cost savings in materials, energy, and direct labor before accounting for carbon incentives or accelerated construction schedules.

Through hotspot analysis, we identified portland cement as the largest remaining carbon contributor even after dramatic reductions—guiding the team toward biomineral substitutes that could achieve an additional 14% savings. We mapped the sensitivity of emissions to manufacturing location, transportation distance, and grid decarbonization scenarios, revealing that strategic siting in low-carbon electricity grids could reduce emissions by 6%, while clean energy procurement and zero-emission vehicle shipping could achieve 13% additional savings.

For operational carbon, we developed a methodology accounting for covariance between hourly electricity demand and grid emission factors using NREL’s Cambium datasets. Analysis showed that PV arrays covering approximately 60% of roof area could offset 100% of annual energy demand, with comercial-scale battery energy storage systems enabling strategic load-shifting when grid emissions are highest.

By combining best-in-class scenarios—optimized mix designs with agricultural byproducts, clean electricity procurement, strategic manufacturing siting, and enhanced operational efficiency—the system could achieve 80-90% total lifecycle carbon reduction. With additional integration of bio-based infill materials for TPMS void spaces and further cement substitution, the pathway to carbon negativity becomes clear.

Project Team:
University of Pennsylvania (Lead PI: Dr. Masoud Akbarzadeh, co-PI Dr. Shu Yang, co-PI Dr. Dorit Aviv), Texas A&M University (co-PI: Dr. Zheng O’Neill), City College of New York (co-PI: Dr. Damon Bolhassani), KieranTimberlake (co-PI: Ryan Welch)

Funding: U.S. Department of Energy Advanced Research Projects Agency-Energy (ARPA-E) HESTIA Program, 2022-2025

Publications & Conference Proceedings

Proceedings of the IASS Annual Symposium, Design of Concrete 3D Printed, Post-Tensioned Spanning Structures with Embedded Triply Periodic Minimal Surfaces, Ororbia, Motavaselian, Chai, Welch, and Akbarzadeh, 2025

Proceedings of the IASS Annual Symposium, Design approach for a post-tensioned funicular concrete beam, Chai, Ororbia, Zhi, Welch, Faircloth, Yavartanoo, Bolhassani, and Akbarzadeh, 2024

Proceedings of the IASS Annual Symposium, An early design stage parametric exploration of integrated concrete funicular floor element and thermal mass performance for carbon footprint reduction, Wang, Chai, Peng, Welch, Akbarzadeh, and Aviv.

More details can be found at the Polyhedral Structural Laboratory website.