IELTS Reading 165: Turning Buildings Into Carbon-Catchers

Adapted from the University of Chicago Pritzker School of Molecular Engineering / Science Advances (November 2025). IELTS Reading Section 3 difficulty, approximately 1,050 words. Source: https://climate.uchicago.edu/news/innovation-turns-building-vents-into-carbon-capture-devices/

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Reading Passage

A. Most people picture direct air capture as a landscape-scale affair: warehouses full of fans, towering over scrubbing towers, sucking carbon dioxide out of the atmosphere at enormous expense and on enormous plots of land. Researchers at the University of Chicago's Pritzker School of Molecular Engineering have now proposed a quieter, dispersed alternative. In a paper published in Science Advances, the laboratory of Assistant Professor Po-Chun Hsu described a carbon nanofibre filter that slots into the ventilation systems homes and offices already possess. Every building, the team points out, already moves huge volumes of air through ducts each day — pulling in fresh air, expelling stale air, running heaters and air-conditioners. If that existing stream could be made to part with its carbon dioxide on the way, every home, classroom and office would become a small capture point, removing carbon directly from the sky without constructing dedicated plants or devoting fresh land to them. The approach borrows a familiar logic from solar energy: a technology once confined to enormous utility farms has been reimagined as a network of small, distributed units strung across the built environment. The analogy is exact. The early solar industry could imagine only vast power stations, until panels shrank cheap enough to bolt onto a rooftop, after which millions of small generators did the work of a few enormous ones. Carbon dioxide, like sunlight, falls roughly evenly wherever a person stands, so there is no technical reason a capture device must sit in one dedicated place.

B. The figures attached to the idea are striking enough to justify the ambition. A full life-cycle analysis, which tallies not only the carbon removed but also the extra emissions created by manufacturing, transporting, installing, maintaining and eventually disposing of the filters, still credits the device with a 92.1 percent net efficiency in stripping carbon dioxide from passing air. Scaled to the largest conceivable level — swapping the filters into every building's ventilation — the team estimates the network could remove up to 596 megatonnes of carbon dioxide from the atmosphere each year, an amount comparable to taking roughly 130 million cars off the road for twelve months. At the individual scale the arithmetic is friendlier still. Because the filter scrubs carbon dioxide inside a building, an air-conditioning system no longer needs to pull in as much outside air to keep indoor levels low, which means less air must be heated or cooled; one 2024 study suggested household energy bills could fall by as much as 21.66 percent. Capture and savings, on this design, travel together rather than pulling against each other.

C. Practical capture, however, is a balancing act, and the material at the heart of the device has to earn its keep. The team built the filter from a carbon nanofibre skeleton coated with polyethylenimine, an amine-bearing polymer that binds carbon dioxide, and engineered it to slot into existing heating, ventilation and air-conditioning racks in much the same way that ordinary HEPA air filters do. The resemblance ends there. Conventional HEPA cartridges are sealed shut with dust after six to twelve months and trucked to landfill, a permanent disposal. The new filter is designed instead to be reusable: once saturated with captured carbon, it can be regenerated — that is, emptied of its load — and returned to service, rather than thrown away. Crucially, the material was chosen for its strong absorption of sunlight, so that regeneration can be driven by solar heat, literally by leaving a loaded filter out in the open. The point is more than cosmetic. The usual way to release carbon dioxide from a liquid solvent is to heat it, and heating it by burning fossil fuel would release more carbon than the system ever captured, defeating the entire enterprise.

D. Imagining a whole city operating this way requires a logistics chain that does not yet exist. The researchers' vision is mundane rather than heroic: municipal waste-collection crews would gather the saturated filters from homes and commercial buildings on their weekly rounds, just as they now collect rubbish and recycling, and swap in fresh cartridges. The loaded filters would be delivered to a central facility, where the captured gas could be released, concentrated, stored underground, or even converted into valuable chemicals or transport fuel. No household would need a chemical plant in its basement; the chemistry would be centralised while the capture stayed scattered. That split — distributed collection, centralised processing — is precisely what made rooftop solar workable on a large scale, and the team argues the same economics could apply to carbon removal, since carbon dioxide in the air is, like sunlight, roughly uniform wherever one stands. The household, on this model, needs no chemical expertise, no pipeline and no contract with a power station; it merely swaps a filter on a schedule, much as it now replaces a cooker hood or a heating element. The heavy industrial work of concentrating and storing the gas is left to the few facilities best equipped to do it.

E. The benefits, though, do not stop at the climate ledger. Because the filter keeps indoor carbon dioxide concentrations low, it also improves the air people actually breathe. In crowded classrooms and open-plan offices, where dozens of occupants exhale the gas by the hour, indoor levels can climb high enough to dull concentration; keeping them down helps occupants stay alert, focused and comfortable. A device that simultaneously cuts household energy bills, scrubs the outside atmosphere and sharpens the minds inside a room is, on paper, a rare piece of engineering with three payoffs for one cost. Whether the design survives contact with manufacturing, humid weather and decades of use remains to be tested, but the principle — that the ducts already in every building could be repurposed as modest carbon-capture infrastructure — is the kind of idea that turns a global problem into a retrofit rather than a monument.

Questions 1-4

Choose the correct heading for paragraphs B, C, D and E from the list of headings below.

List of Headings i. The numbers behind a distributed network ii. How nanofibres are manufactured in space iii. A reusable filter designed for solar-powered regeneration iv. The cost of landfill disposal v. A city-scale logistics chain that does not yet exist vi. Why carbon dioxide is poisonous to plants vii. Three payoffs from one device

1. Paragraph B: ____
2. Paragraph C: ____
3. Paragraph D: ____
4. Paragraph E: ____

Questions 5-8

Choose the correct letter, A, B, C or D.

5. What distinguishes the new filter from a conventional HEPA filter? A. It is thrown away after six months. B. It can be regenerated and reused rather than landfilled. C. It removes only dust, not carbon dioxide. D. It requires a separate dedicated building.

6. Why did the team design the material to absorb sunlight? A. To heat buildings during winter. B. So the loaded filter can be regenerated using solar heat. C. To make the filters look attractive. D. To block ultraviolet radiation.

7. According to the passage, how would saturated filters be collected? A. By dedicated carbon-capture trucks only. B. Through existing municipal waste-collection rounds. C. By individual households driving them to plants. D. They would be left in place indefinitely.

8. Why is burning fossil fuel to regenerate the solvent undesirable? A. It would release more carbon than is captured. B. It damages the nanofibre material. C. It makes the filter too expensive. D. It reduces indoor air quality.

Questions 9-13

Do the following statements agree with the claims of the writer?

Write:

• TRUE if the statement agrees with the information
• FALSE if the statement contradicts the information
• NOT GIVEN if there is no information on this

9. The new filter is claimed to be 92.1 percent efficient even after accounting for its own emissions.
10. Replacing all building filters could remove about 596 megatonnes of carbon dioxide annually.
11. The filter is most effective in cold climates.
12. Keeping indoor carbon dioxide low may help people stay more alert.
13. The technology is already widely deployed across many countries.

Questions 14-15

Complete the summary below using NO MORE THAN TWO WORDS from the passage.

Unlike disposable HEPA filters that go to landfill, the new cartridge is designed to be (14) __________ and emptied of its carbon load, ideally using (15) __________ heat.

Answers & Explanations

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