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11/20/2025
WT Staff
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Friday, November 21, 2025 427 pm EST
White to ultra-white: The latest "Cool Roof" technology harvests moisture from the air
Reflective coatings on commercial and residential structures are well known for deflecting solar radiation, reducing rooftop surface temperatures to keep interiors cooler in the hottest parts of the world. An advancement in cool roof science from University of Sydney Nano Institute goes beyond reducing energy demand, Dr. Chiara Neto and Dr. Ming Chiu and colleagues have patented a new roofing technology that can fill a water reservoir overnight.
Dr. Chiara Neto is Professor of Physical Chemistry at University of Sydney and the Chief Scientific Officer for Dewpoint Innovations. WT caught up with her in her native Italy to hear about the new sustainable technology for buildings, developed with Dr. Ming Chiu, Chief Technical Officer at Dewpoint.
Dr. Neto earned her Chemistry titles at University of Florence, Italy, going on to establish herself as an expert in functional nanostructured surfaces, cited for her extensive work on interfacial flow and surface wetting. Neto teamed up with Dr. Chiu, with his expertise in structured polymeric surfaces for atmospheric water capture. Dr. Chiu applied a decade of experience with industrial coatings formulation and deep knowledge of international standard operations (ISO) to create the coolest Cool Roof system to date.
Dewpoint's concept developed from 2019 to a successful rooftop prototype, assessed over a six month period in Sydney, Australia. The results of this investigation were published in Advanced Functional Materials journal last month. The authors, including Neto and Chiu, conclude their cool roof coatings will "advance the provision of sustainable, delocalized and low-cost sources of water from the atmosphere". The ultra-white, reflective paint adheres well to most surfaces without primer. The protective coating turns metal, tile and cement rooftops into a surprisingly productive element of the building envelope, capable of collecting as much as a litre of water for every 2.5 square metres of roof surface. The technology is cost effective, can be applied to existing structures, diverting 96% of the solar radiation, reducing energy demand and heat island effect.
History of the Cool Roof concept
According to the US based Green Building Alliance, "Over the past few decades, rooftops have become a large contributor to excessive heat issues. As many as 90 percent of roofs in the United States are poorly designed and built with dark, non-reflective, heat-absorbing materials. Because of this, rooftop temperatures can rise up to 90 degrees Fahrenheit above the prevailing air temperature."
Bright, white buildings and rooftops have been around for centuries in southern Europe and north Africa, while dark colored rooftops are the aesthetic favored in the North American market. Research into cool roof technology may have started in California around 2001. In 2017, the investigation extended to one of the hottest urban centers on the planet. A pilot project in western India converted thousands of rooftops to measure the mitigative potential of cool, white roofing calming the heat island effect. In Ahmedabad City, summer temps can hit above 50C. Three thousand rooftops were painted with white lime and a reflective coating, the change in surface and interior temperatures recorded. US-based Natural Resource Defense Council commented in a 2019 BBC investigative piece, following up on a pro-cool roof statement from former UN Secretary General, Ban ki Moon. BBC News Reality Check team examined the evidence and reported there is indeed a cooling benefit associated with white and reflective roof surfacing, though not the 7C suggested by Moon. Research of the day validated a 2 to 5C lower interior temperature for the white rooftops over the darker version.
By the time Neto and Chiu began their own version of cool roof/water collection, utilizing nanotechnology in Australia, the Berkeley Lab in California was mapping heat units absorbed by various roof surfaces in 2019. The Berkeley Heat Island team measured the ultraviolet, visible, and near-infrared light penetration of Los Angeles structures, recording temperatures on the outer surface and interiors of buildings with reflective vs traditional roofing. The research showed traditional dark colored roof materials absorbing the full spectrum of solar energy, resulting in the highest surface and interior temperatures. Rooftops surfaced in lighter colors, and those of the same color with higher reflective qualities demonstrated significant cooling effects, both inside and outside the building. The study by Lawrence Berkeley National Laboratory (Berkeley Lab) for the California Air Resources Board found a surface deflecting 35% of the sun's energy measured 12°C (22°F) cooler than a non-reflective, traditional roof.
Neto, Chiu and the team at Dewpoint have advanced the cool roof study to utilize extremely fine particles, measured in nanometers rather than micrometers in their paint composition. The reflected solar radiation jumped from 70% in the next best white paint, to 96% with the Dewpoint Innovation. Without missing a step, Dewpoint has designed this sustainable technology to make the most of the cooling effect, passively harvesting water from the atmosphere. Widely reported as a unique and valuable feature for arid and semi-arid regions, the Dewpoint cool roof promotes condensation when surface temperature drops below dewpoint. Condensation runs down the roof into collector lines and into a reservoir. According to Neto, the moisture collection feature is most impressive when humidity is above 70%, the temp 15 to 25C, with relatively low wind conditions, below 11 or 12 km per hour. Where the daytime temperatures are too high for moisture harvesting, significant accumulations gather overnight.
What's in it for property owner/managers?
For those willing to make the leap from dark to white, the building energy savings are significant. As architectural controls slowly adjust for the energy transition, North American developers may shift away from the popular dark roof to realize up to 40% energy cost reductions. The Dewpoint rooftop's passive contribution to household water reserves is more than a bonus. For severely water challenged regions, water capture may become a design driver for the new neighborhood aesthetic. Western Municipalities will be taking a good look at this advanced cool roof technology, adapting building standards, policy and programs to incentivize the shift to ultra-white in the near future.
Dewpoint Innovations, here.
See University of Sydney Nano Institute, here.
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