Business

Chinese scientists develop Sunflower-like AC

By Sohail Khan 28 September 2026, 4:00 pm

Benchmarks
Nifty22,780.25-360.25

FEATURED FUNDS★★★★★

Motilal Oswal Midcap Fund Direct-Growth

5Y Return
20.4 %

Invest Now

Enter search text:

Business News›News›Trending›Sunflower-like AC: Chinese scientists develop a cooling system that follows Sun and provides 135% higher cooling during hot noon. Here's how it works

Read Today's Paper

Sunflower-like AC: Chinese scientists develop a cooling system that follows Sun and provides 135% higher cooling during hot noon. Here's how it works
Synopsis

Chinese scientists built sunflower-like AC: Researchers in China have developed a sunflower-inspired radiative cooling system that changes its orientation with the Sun to reduce direct solar heating while continuing to radiate heat toward the sky. The system, called dynamic sky view factor steering (DSVFS), delivered 135% higher cooling flux at solar noon than a fixed horizontal emitter in experiments. The September 2026 study is an arXiv preprint and has not yet been peer reviewed.

Sunflower cooling system — China researchers develop a sunflower-inspired cooling system that follows the Sun, boosting daytime radiative cooling by 135% in experiments.

What if a cooling panel did not have to stay in one position all day? Researchers in China are testing a system that moves a radiative-cooling surface as the Sun travels across the sky. The idea borrows from the movement of sunflowers, although the goal is the opposite: instead of seeking sunlight, the device tries to avoid taking in too much of it. The experimental system, called dynamic sky view factor steering (DSVFS), produced substantially more cooling at midday than an identical surface kept flat, according to a September 2026 research paper published as an arXiv preprint. The researchers reported a 135% higher cooling flux at solar noon with the moving system. The work has not yet been peer reviewed.

The problem is sunlight

Radiative cooling works by allowing a specially engineered surface to send heat away as infrared radiation toward the sky. The approach is attractive because it can potentially cool objects without the energy-intensive refrigeration cycle used by conventional air conditioners. Daylight creates a major complication.

A surface that is supposed to lose heat is simultaneously being exposed to the Sun. Even highly reflective cooling materials can struggle when solar radiation adds more heat than the surface can reject. The Chinese researchers approached the problem from a different direction. Instead of trying to make the material deal with sunlight from every angle, they changed the angle of the material itself.

A sensor tracks the Sun and a two-axis mechanism adjusts the cooling surface. During periods of strong direct sunlight, the emitter is positioned to reduce the amount of solar energy falling directly onto it. That movement comes with a cost. A surface tilted away from the Sun can also lose part of its view of the sky, which is where it needs to send its infrared heat. DSVFS is designed to find a balance between the two.

A 30 W/m² surface reached 71 W/m²

One of the experiments used a specially prepared radiative-cooling paint with a measured solar absorptivity of 4.6%. When the surface was kept horizontal at solar noon, its cooling flux was measured at 30 W/m². The moving version reached 71 W/m² under the same general conditions. The researchers reported this difference as a 135% improvement in cooling flux.

The dynamically positioned emitter was also measured at about 1.1°C below the temperature of the fixed emitter at noon. It was around 2.2°C cooler than the surrounding air at that point. Across the daytime experiment, the researchers reported an average temperature advantage of about 0.8°C over the horizontal configuration, while the emitter remained roughly 3°C below ambient. The tracking hardware required energy as well, averaging around 2 W/m².

The more difficult test involved black paint

The researchers then put the concept through a much tougher test. They used an aluminium plate coated with commercial black paint. The surface had a solar absorptivity of 99.6%, so it absorbed nearly all incoming sunlight. Under normal circumstances, a surface with those properties would be poorly suited to daytime radiative cooling.

The researchers added a very thin nanoporous polyethylene layer to help block residual diffuse sunlight while allowing infrared radiation to pass. The comparison produced a striking result. The horizontally positioned black surface could not cool below ambient during the daytime. When the DSVFS mechanism was used, however, the emitter remained an average 6.2°C below ambient during the daytime.

At noon, it was measured at 5.1°C below ambient. The researchers also reported a 23.9°C temperature difference between the dynamically steered surface and the horizontal black-paint surface at solar noon. That experiment suggests the benefit may not depend entirely on using a highly specialised cooling coating.

It does not simply follow the Sun

The sunflower comparison can be slightly misleading if interpreted as ordinary solar tracking. The objective is not to keep the cooling surface pointed at the Sun. It is to manage the relationship between the Sun and the sky.

When direct solar radiation is strong, the surface changes its orientation to limit solar exposure. But it still needs sufficient access to the sky for radiative heat transfer. When sunlight becomes diffuse because of cloud cover, the researchers say the system can return to a horizontal position. It also goes back to that position after sunset. That makes the mechanism a form of active geometric control, rather than simply a solar-tracking system.

Earlier experiments showed the sky can be used as a heat sink

The concept builds on years of research into radiative cooling. Scientists demonstrated in earlier work that carefully designed surfaces can reject heat toward the sky even during the day. A 2018 Nature Communicationsstudy used a directional structure to deal with sunlight and reported cooling of about 6°C below ambient around solar noon.

Another study published in Nature Energy in 2017 demonstrated non-evaporative cooling of water using spectrally selective surfaces. The researchers reported water temperatures up to 5°C below ambient and heat-rejection fluxes reaching 70 W/m². The new Chinese approach differs by making the orientation of the cooling surface itself dynamic.

The researchers see potential beyond the laboratory

The team also used computer modelling to estimate how the approach might perform with a commercially available cooling paint. The model considered conditions from June to September across locations in China and the United States. According to the researchers, the simulations produced summer cooling-energy savings above 150 kWh/m² in many areas, with a maximum of about 200 kWh/m² in the locations studied.

Those figures should not be interpreted as measured savings from an operating building. They are modelling results intended to estimate the technology's potential. That distinction matters because a laboratory setup and a cooling system installed on a building face very different challenges.

The next question is durability

The experiment points to an unusual possibility in cooling technology: instead of relying only on better materials, engineers could use movement to change how those materials interact with sunlight and the sky. But the technology remains at an early research stage.

The paper is currently an arXiv preprint, so its findings have not yet been independently evaluated through peer review. Long-term performance, mechanical reliability, maintenance requirements and the energy cost of repeatedly moving the cooling surface will also matter if the concept is eventually adapted for buildings or other practical applications. For now, the experiment offers a different way to think about daytime cooling.

The material does not simply have to fight the Sun. The researchers are trying to move the material out of the Sun's way.

Add as a Reliable and Trusted News Source
Add Now!

(You can now subscribe to our WhatsApp channel)

(You can now subscribe to our WhatsApp channel)

Read More News on
sunflower acsunflower cooling systemdynamic sky view factor steeringChina cooling researchsolar energyNature Communications

Enter search text:

Continue reading with one of these options:
Limited Access
Free
Login to get access to some exclusive stories

& personalised newsletters
Login Now

Unlimited Access
Starting @ Rs120/month
Get access to exclusive stories, expert opinions &

in-depth stock reports
Subscribe Now

Unlock Access to All Exclusives with ETPrime FREE TRIAL

15 Days Free: Unlock All ETPrime Exclusives, Market Tools & ePapers

Trial offer expiring in00 : 05 : 00

I'd rather pay ₹2599 now

Uh-oh! This is an exclusive story available for selected readers only.

Worry not. You’re just a step away.

Prime Account Detected!

It seems like you're already an ETPrime member with

Log out of your current logged-in account and log in again using your ET Prime credentials to enjoy all member benefits.

Unlock ETPrime's Exclusive Stories Today!

Subscribe to gain powerful insights on business, stock market and industry trends.

Big Price Drop! Flat 40% Off

Student Only Offer

Already a Member? Sign In now

Already a Member? Sign In now
Already a Member? Sign In now

Offer Exclusively For You

Save up to Rs. 700/-

ON ET PRIME MEMBERSHIP

Avail Offer

Offer Exclusively For You

Get 1 Year Free

With 1 and 2-Year ET prime membership

Avail Offer

Offer Exclusively For You

Get 1 Year Free

With 1 and 2-Year ET prime membership

Avail Offer

Offer Exclusively For You

Get Flat 40% Off

Then ₹ 1749 for 1 year

Avail Offer

Offer Exclusively For You

ET Prime at ₹ 49 for 1 month

Then ₹ 1749 for 1 year

Avail Offer

Special Offer

Get flat 40% off on ETPrime

Avail Offer
Avail Offer

Claim NowAlready a Member? Sign In now

Need Assistance?

Connect with an ETPrime expert for personalized support and guidance

+91 9484700004

' + h3 + '

' + h4 + '

' + listing + '

What’s Included with

ETPrime Membership

1Exclusive Insights That Matter

Uncover the truth with our investigative stories

Make strategic moves using the real-world case studies

Read industry-specific stories to identify emerging trends

Spot opportunities with in-depth insights that matter

Trump temper on H-1B visas is forcing Indians to do these things to stay put in US

What Adani’s US indictment means for India Inc’s overseas fundraising
Why veterans like Reliance, L&T are on acquisition spree? Aswath Damodaran has an answer.

Will China’s dollar bond sale in Saudi Arabia trump the US in financial world?
Huawei launches its own OS to compete with Google and Apple. But can it win beyond China?

The problem with lab grown diamonds
Why a falling rupee is a better option for the economy

A list of top 20 momentum stocks that have delivered massive returns in one year