New air filter turns buildings into carbon-capture machines

Air flows through every building in which we spend time – in our homes, offices, schools, and stores. Heating and cooling systems keep that air moving, but they also carry tiny particles, dust, and too much carbon dioxide (CO₂).

We can now use advanced air-filter technology to clean this indoor air. A new device could reshape how we manage CO₂ – and even trim energy bills along the way.

Turning air filters into CO2 removers

Right now, the biggest efforts to pull CO₂ out of the atmosphere rely on massive industrial machines that cost a fortune and need a lot of space.

The new approach flips that idea. Instead of building big carbon-capture plants, what if we could use the air systems already in place in every home, office, and school?

That’s the goal of a new filter developed by researchers at the University of Chicago’s Pritzker School of Molecular Engineering. It looks a lot like the air filters we already use – but it does much more.

These filters are made from carbon nanofibers and a material called polyethylenimine, or PEI. Together, they trap CO₂ from the air as it flows through HVAC systems.

A full life-cycle analysis found the filter removes 92.1% of CO₂ from the air, even after counting emissions created from manufacturing, transporting, and eventually disposing of the filters.

Same air filter system, new superpower

“Every building already has ventilation systems that move large volumes of air every day. 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,” explained Ronghui Wu, who worked on the project as a postdoctoral researcher.

That makes this tech more than just useful – it’s scalable. If every building used this kind of filter, we could remove up to 596 megatonnes of CO₂ from the atmosphere per year. That’s like taking 130 million cars off the road for a full year.

But even on a small scale, the benefits are clear. In 2024, a study showed that these filters could help cut energy bills by as much as 21.66%.

Lower carbon dioxide, lower costs

Why would a carbon-catching filter help you spend less on energy? It comes down to how air-conditioning systems work.

Normally, HVAC systems have to bring in a lot of outside air to keep indoor CO₂ levels down. People have to heat or cool that air, depending on the season – and that costs money.

“Our filter removes carbon dioxide inside the building, so the system doesn’t have to bring in as much outside air. That means less air needs to be heated or cooled, which reduces the energy consumptions in HVAC,” Wu explained.

So, while your air is getting cleaner, your wallet isn’t taking as big a hit.

The filters can be used repeatedly

A big question with any reusable tech is: how do you clean it or get it working again? Because of their design, people can reuse these filters repeatedly. The trick? Sunlight.

The material absorbs heat from the sun. That heat removes the captured CO₂ from the filter without using extra energy. There’s no need to burn fuel or use expensive heating systems. Just leave the filter out in the sun and it regenerates.

“It has to be able to regenerate using renewable energy,” said lead researcher Po-Chun Hsu.

“The most common way to regenerate CO₂ with solvent, is by heating it up. If you burn fossil fuels to heat up the solvent, then you will probably end up emitting more carbon dioxide than you capture.”

Reusable and recyclable filters

Unlike standard filters, which are tossed in the trash every six months or so, these DAC (direct air capture) filters are built for reuse.

They are designed to fit into current HVAC systems, much like HEPA filters. But instead of heading to landfills, they can be collected and refreshed.

Hsu sees a future where cities manage these filters just like they handle garbage and recycling. Used filters could be picked up, sent to a central location, and stripped of their CO₂. The captured carbon could then be turned into fuels or chemicals, adding value instead of waste.

“They would have these saturated filters from household ventilation systems and commercial buildings, then replace them with new ones,” Hsu said.

“They’d ship the saturated one to a centralized facility to dissolve the CO₂ or make it into highly concentrated CO₂ to capture or, even better, convert to high-value chemicals or fuel.”

Filters that improve indoor air quality

Beyond energy savings and climate impact, there’s another benefit that hits close to home – better indoor air.

“This kind of air filter can also improve indoor air quality, especially in places like classrooms and offices where many people share the same space,” Wu said. “By keeping indoor carbon dioxide levels low, it helps people stay more alert, focused, and healthy.”

This isn’t just a cleaner filter. It’s a smarter one. It captures carbon, saves money, uses sunlight, and keeps us healthier. And it all fits into systems we already use every day. That’s what makes it powerful.

If this technology catches on, buildings around the world could become quiet climate helpers – one HVAC system at a time.

The full study was published in the journal Science Advances.

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