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One Paint, Two Birds : It Cools the Home AND Pulls Water from the Air
So why is Prof. Bivas Saha's innovation still sitting on a lab shelf — and who will pick up the baton?
Context
Scientists develop smart paint that reflects 97% of sunlight, and heatwave cities may get a cheaper weapon against AC demand 09 June 2026 / OkDiario
Extract
A team at the University of Sydney with the startup Dewpoint Innovations has made a paint-like coating from a porous polymer (PVDF-HFP) that reflects up to 97% of sunlight while cooling itself below air temperature — which also lets water vapour condense on it. In rooftop trials it stayed about 11°F cooler than the surrounding air, collected dew on roughly a third of the year's days, and at favourable times a ~129 sq-ft patch yielded close to 1.24 gallons of water a day — no electricity, no moving parts. Lead researcher Prof. Chiara Neto frames the vision as roofs that stay cooler and make their own fresh water. Published in Advanced Functional Materials.
Two threads of mine just collided
For me, this single news item ties together two separate campaigns I have run on these pages for years.
Thread 1 — "Water from Thin Air" ( my 7-year pursuit )
Since February 2018 ( Déjà Vu? #Latur #Marathwada #Waterwar ) I have urged our leaders to embrace atmospheric water harvesting — pulling drinking water straight out of dry air. I pointed specifically to Prof. Omar Yaghi and his Metal-Organic Frameworks (MOF), even sharing his phone number, and asked Maharashtra to simply call him.
Seven years later, in 2025, Prof. Yaghi won the Nobel Prize in Chemistry for exactly that work — and his company Atoco now sells a container-sized, solar-powered unit that makes ~1,000 litres of clean water a day from 20%-humidity desert air, targeting ~1 cent per litre. ( My May 2026 reminder : Dear Devendrabhai — village women are trekking 10 km for water )
That is the heavy-lifter route : powerful, dedicated, but a standalone capital device — you must buy the box, the MOF sorbent, the solar panels.
Thread 2 — "Radiative Cooling Paint" ( my note of Jan 2024 )
On 6 January 2024 I congratulated Prof. Bivas Saha and his JNCASR team ( Congrats, Prof Bivas Saha (JNCASR) ), who had developed an MgO-PVDF radiative cooling paint that dropped surface temperatures by over 10°C — nearly double the cooling of ordinary white paint. In that note I laid out a full roadmap : technology transfer to paint makers, a PLI scheme, a mandatory Building Code for cool roofs, and carbon credits computed by BEE.
The "Two Birds, One Stone" insight
Here is what struck me about the Sydney paint :
A radiative-cooling paint is no longer only a cooling technology. It is quietly also a water-harvesting technology.
And notice the full chain of benefits from a single coat of paint :
- Reflects ~97% of sunlight → building stays cooler
- Cooler building → air-conditioners run less
- Less AC → less electricity drawn
- Less electricity → less fossil fuel burnt → less CO₂ ( in my 2024 note, BARD estimated India's AC load at ~180–200 TWh/yr and ~144–164 million tonnes of CO₂; a 10% cut ≈ 14–16 MT CO₂ and $140–160 million in tradable carbon credits )
- AND the same cool surface condenses water from the air — for free
So the MOF device ( Thread 1 ) and the cooling paint ( Thread 2 ) are not rivals — they are two scales of the same mission :
| MOF water-harvester (Atoco/Yaghi) | Radiative cooling paint (JNCASR/Sydney) | |
|---|---|---|
| Role | Dedicated heavy-lifter | Distributed, passive layer |
| Water output | ~1,000 L/day per unit | A few L/day per rooftop, at near-zero marginal cost |
| Best for | Acute drought, emergency supply | Mass rollout across millions of roofs |
| Bonus | — | Cuts AC, electricity, CO₂ as well |
One fights the drought village by village. The other fights heat-and-water stress roof by roof, by the crore. India should deploy both.
A respectful word to the Ministry of Science & Technology
Dr. Jitendra Singh ji — Hon'ble Minister of State (Independent Charge), Ministry of Science & Technology
JNCASR is an autonomous institute under your own Department of Science & Technology. Prof. Saha's cooling paint was reported by DST itself back in November 2023. Yet two and a half years later, where is the aggressive, mission-mode push to take it from lab bench to terrace roof?
You yourself said recently that science must travel from the laboratory to the market, from ideas to impact. I could not agree more — and I respectfully submit that this paint is the textbook case. A home-grown, low-cost, climate-AND-water innovation has been allowed to sit quietly while the world's labs race ahead ( Sydney has now added water harvesting on top ).
May I gently ask : what would it take for DST to treat Prof. Saha's paint as a flagship "lab-to-market" success story this year, not someday?
Dear Shri Nadda ji — please pick up the baton and run
Shri Jagat Prakash Nadda ji — Hon'ble Union Minister, Ministry of Chemicals & Fertilizers
A cooling paint is, at heart, a chemical product — and therefore squarely within your Department of Chemicals & Petrochemicals. You are already, by your own recent words, building new chemical parks, boosting domestic manufacturing, and cutting import dependence. Here is a ready-made cause :
- Convene Prof. Saha (JNCASR) with the major paint manufacturers for a structured technology-transfer round-table.
- Announce a PLI ( Production Linked Incentive ) scheme for radiative-cooling / atmospheric-water-harvesting paints — a new, exportable category India can lead rather than import.
- Fund a JNCASR ⇄ Sydney head-to-head field trial under Indian summer + monsoon conditions, so the Indian formulation captures both the cooling and the water-harvesting frontier.
- Coordinate with CSIR-NCL Pune / IIT Bombay ( already strong in MOF chemistry ) so that both threads — the device and the paint — are Made in India.
If the chemical sector is to become "modern, competitive and self-reliant," let it own the world's first paint that cools a home and waters a garden at the same time.
And the original asks still stand ( 2024, restated )
- Ministry of Housing & Urban Affairs ( I had addressed Shri Hardeep Singh Puri ji in my 2024 note ) : amend the Building Construction Code to mandate this paint on roofs/terraces of all new buildings, with an advisory for exterior walls.
- Bureau of Energy Efficiency ( BEE ) : compute the electricity saved per litre of paint, and fix the carbon credits earned per unit, tradable on the National Carbon Trading Exchange. I still believe a manufacturer may earn more from the carbon credits than from the paint itself.
- Ministry of Jal Shakti : evaluate roof-coating water harvesting as a low-cost supplement to rainwater harvesting for water-scarce districts, remote schools and PHCs.
Dear Paint Manufacturers — the window is open NOW
In 2024 this was a cooling paint. In 2026 it is a cooling-AND-water paint. By 2028 it should not be an imported paint. Please approach Prof. Saha for technology transfer :
Prof. Bivas Saha — JNCASR — bsaha@jncasr.ac.in
| Manufacturer | Contact |
|---|---|
| Asian Paints — asianpaints.com | proffice@asianpaints.com · csr@asianpaints.com |
| Berger Paints — bergerpaints.com | consumerfeedback@bergerindia.com |
| Kansai Nerolac Paints — nerolac.com | gtgovindarajan@nerolac.com · complaints@nerolac.com |
| AkzoNobel India (Dulux) — dulux.in | customercare.india@akzonobel.com |
| Nippon Paint India — nipponpaint.com/india | tu@nipponpaint.co.in |
| Indigo Paints — indigopaints.com | info@indigopaints.com · secretarial@indigopaints.com |
| Shalimar Paints — shalimarpaints.com | feedback@shalimarpaints.com · ashok.gupta@shalimarpaints.com |
| British Paints India — britishpaints.in | sales@britishpaints.in |
| Jotun Paints — jotun.com/in-en | jotun.mumbai@jotun.com |
| Jenson & Nicholson — jnpl.in | branding@sheenlac.in · md@sheenlac.in |
The science has spoken — twice over. A Nobel Prize validated the device. A Sydney lab has now shown the paint can do double duty. India has the scientist ( Prof. Saha ), the industry ( above ), and the need ( heat + water, in every drought district ).
All that is missing is a phone call and a push. Two birds. One stone. Let us not wait another seven years.
With Regards,
Hemen Parekh www.HemenParekh.ai / 16 June 2026
PS : Chat with my Digital Avatar at www.hemenparekh.ai
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