The Science Advances study demonstrates that polyethylenimine nanofiber filters, designed to fit into existing HVAC systems like HEPA elements, can capture indoor CO2 with 92.1% efficiency in lab tests. Researchers say global adoption could reduce emissions by about 596 megatonnes per year—equivalent to removing 130 million cars. The filters can be regenerated using solar thermal heat and may lower HVAC energy use by reducing the need for outside air. The study does not analyze commercialization requirements or real-world deployment costs.
Nanofiber HVAC Filters Could Remove Nearly All Indoor CO2, Study Shows
An HVAC technician works on a ventilation system. The University of Chicago says it has developed a filter that can capture most of the CO2 in a building.
A new study in Science Advances reports that a carbon-capture nanofiber filter designed to fit into building ventilation systems like a HEPA element can remove nearly all the carbon dioxide from indoor air. The approach could cut emissions, reduce HVAC operating costs and be deployed without building new infrastructure, researchers say.
How the Filters Work
The research team created distributed carbon-capture filters from polyethylenimine (PEI) formed into nanofibers that are sized to be slotted into existing HVAC filter bays. In laboratory tests the filters achieved 92.1% CO2 removal efficiency, a performance the authors say is sufficient to offset the CO2 generated by commercial manufacturing and distribution of the filters themselves.
Practical Deployment and Regeneration
Building operators would install the carbon-capture elements the same way they fit HEPA filters into HVAC units. As the filters become saturated, they can be removed and either regenerated on-site or shipped to a centralized facility for carbon recovery. The researchers note several regeneration pathways, including dissolving or concentrating the captured CO2 for storage or converting it into higher-value chemicals or fuels.
“Every building already has ventilation systems that move large volumes of air,” said Ronghui Wu, an assistant professor at Nanyang Technological University who led the research while at the University of Chicago. “By integrating our carbon-capture filters into these systems, we can remove carbon directly from the air without building new plants or using extra land. It’s a practical and scalable way to make carbon capture part of everyday infrastructure.”
Solar Thermal Regeneration
Polyethylenimine has high solar absorptivity, which the authors say enables solar thermal regeneration. That means the filters can be heated by sunlight to release captured CO2 without requiring large additional energy inputs, potentially lowering lifecycle energy use for regeneration.
Operational Benefits
Lower indoor CO2 concentrations may allow HVAC systems to draw less outside air while maintaining air quality standards, reducing the volume of air that must be heated or cooled. The researchers expect this could cut building energy consumption and operating costs.
Scale and Limits
Looking at the big picture, the authors estimate that if similar filters were installed in buildings worldwide, annual emissions reductions could reach 596 megatonnes—roughly equivalent to taking about 130 million cars off the roads. The published paper focuses on filter design and performance tests; it does not include a detailed analysis of what would be required to commercialize the filters at scale.
Note: Results reported are from controlled experiments and modeling in the study; real-world performance, costs, supply-chain impacts and policy or regulatory considerations for widespread deployment remain to be analyzed.
