i2Cool - Passive Radiative Cooling Paint to Save Energy and Reduce Carbon Emissions

To provide significant benefits to society, outstanding research achievements need to be transformed into practical applications. Research assistant Shirley Du and PhD student Martin Zhu, from the School of Energy and Environment (SEE) of CityU, and other team members decided to turn the scientific research findings of their supervisor, Dr Edwin Tso Chi-yan, an assistant professor in the SEE, into a product that would have a significant impact on society and the environment. They set up a start-up company called “i2Cool” to develop and promote zero-energy, low-cost, highly-efficient passive radiative cooling paint to save energy and reduce carbon emissions in cooling buildings.

The invention of the innovative radiative paint was inspired by the surface hair structure of the Sahara Desert ant that can resist the blazing sun. When applied to the exterior wall of a building, the paint can simultaneously reflect most of the sunlight and dissipate the building's heat into space in the form of mid-infrared radiation, resulting in a significant drop in the building's indoor temperature.

This newly developed technology was awarded the “Gold Medal with Congratulations of the Jury” at the Inventions Geneva Evaluation Days (IGED) in 2021. In addition to receiving a $100,000 seed fund from CityU’s “HK Tech 300”, the team was champion in the Hong Kong Chapter and 1st runner-up in the global final round of “Maker in China” SME Innovation and Entrepreneurship Global Contest 2021. The team's technology has also received attention from Hong Kong government departments and private developers, and the team has been invited to test the environmentally friendly paint in various buildings.

Inspired by ants found in the Sahara Desert

The technology was inspired by an ant species found in the Sahara Desert, which can survive in the high-temperature desert because of its special surface hair structure. The team studied the mechanism of reflecting sunlight and dissipating heat passively in the ant hair structure and then incorporated the technology into a mixture of polymers and nanoparticles to produce the innovative paint. The paint can simultaneously reflect most of the sunlight and dissipate the building's heat into the cold outer space through mid-infrared radiation, achieving a significant cooling effect and reducing the need for air conditioning.

The cooling paint obtained a patent in Hong Kong, which is held by CityU.

The team's technology was inspired by the surface hair structure of a Saharan Desert ant. (Photo courtesy of i2Cool team/ Shi, Norman Nan, et al., Science 349.6245 (2015): 298-301.)

Transforming technology into practical applications

A group of PhD students and research assistants, including Shirley and Martin, studied Dr Edwin Tso's technology and focused on transforming the technology into practical and useful applications. A Hong Kong government department noticed their innovative technology and invited them to collaborate on a test of the paint's cooling performance on a real building.

“We tested the cooling effect of the paint on the rooftop of the Tung Chung InnoTCE building in Hong Kong and found that the paint lowered the indoor temperature by 5 to 6 degrees Celsius, reducing air conditioner electricity use by 8 to 10%,” said Shirley.

The i2Cool team tested the paint on the rooftop of the Tung Chung InnoTCE building in Hong Kong. The picture on the left shows the middle part of the rooftop coated with the team's white paint, and the picture on the right shows that the surface temperature measured in the painted area (dark blue section) was about 30 degrees lower than that in the uncoated area (red section). (Photo courtesy of the i2Cool team)

“The paint can also be used to make wallpaper and applied to the roofs and exterior walls of buildings to achieve the same cooling effect, reducing the need for electricity,” added Martin. The self-cooling technology has many advantages, such as a simple paint structure, ease of manufacturing and low cost.

Led by Dr Tso, the team was awarded the Gold Medal with Congratulations of the Jury at the IGED in 2021 for its unique cooling technology. At the time, they had not yet formally set up i2Cool. But news of their award attracted the attention of private companies interested in their technology. Since then, many companies have invited the team to conduct tests.

When CityU announced the “HK Tech 300” programme, Dr Tso and his team decided to join the HK Tech 300 plan to “get the technology off the ground”. A group of PhD students and research assistants took the lead in June to establish the start-up company, called i2Cool, to promote the passive radiative paint, with Dr Tso acting as an advisor. So the launch of HK Tech 300 led to the birth of i2Cool.

Attending a special reception are Professor Way Kuo, CityU President (seventh from right), Professor Michael Yang Mengsu, Vice-President (Research and Technology) (sixth from right), and the CityU winners of the Inventions Geneva Evaluation Days (IGED) 2021. Fifth from right is Dr Edwin Tso, Assistant Professor in the School of Energy and Environment of CityU.

HK Tech 300 supplements business knowledge

The team members of i2Cool are all scientific researchers who are familiar with the details of the technology. But the promotion of new technology involves commercial operations, which are not their specialty. Neither Shirley nor Martin had any idea about how to start a business or marketing.

“Fortunately, we participated in HK Tech 300 and got the opportunity to participate in various innovation and technology events and competitions. We also met people from different fields and exchanged ideas with other start-up teams. We gradually figured out our product positioning, selling points, customer goals, and so forth,” said Shirley.

“The mentor we were matched with in HK Tech 300 gave us valuable advice on our business model and customer goals, helping us set the direction for our company's development,” added Martin.

“Our mentor gave us advice on how to make our products relevant to the needs of the market and encouraged us to develop more products,” said Shirley. “For example, our first cooling paint is white, and our team is now studying the use of different colours, and even using the new technology on other materials, like clothing.”

The team received $100,000 from the HK Tech 300 seed fund, which will be used to develop technology, purchase equipment such as mixers, buy raw materials, and so on. The team is also preparing to apply for HK Tech 300's $1 million Angel Fund to further support the company's product development and growth.

i2Cool received a $100,000 seed fund from HK Tech 300. Dr Edwin Tso (third from right), Shirley Du (third from left), Martin Zhu (second from left) and other team members. (Photo courtesy of the i2Cool team)

The i2Cool team stood out from 116 entries to win first prize in the Hong Kong Chapter of the “Maker in China” SME Innovation and Entrepreneurship Global Contest 2021 in August. Then they represented Hong Kong in the global final to compete with contestants from Central and Eastern Europe, ASEAN countries, Japan and Korea, as they sought support to enter the Greater Bay Area market, by matching with mainland investors, gaining entry to entrepreneurial parks, and receiving guidance on how to transform technological achievements into marketable products. They won 1st runner-up.

i2Cool was awarded first place in the Hong Kong Chapter of the “Maker in China” SME Innovation and Entrepreneurship Global Contest 2021 (Photo courtesy of Cyberport)

i2Cool was also the award-winning start-up team in the initial idea stage of the “Climate Action Recognition Scheme (CARS) 2020-21”. By working with organisations and institutions in the construction, energy and painting sectors, i2Cool hopes to develop technologies that will have a significant environmental and social impact, help alleviate the energy shortage and reduce carbon emissions, and contribute to the overall sustainability and economic growth of Hong Kong.

The goals are ambitious, but as the saying goes, a journey of a thousand miles begins with a single step. Although they are still in the exploratory stage of their entrepreneurial journey, he suggested, “For those who wish to start their own business, it’s important to grasp the ‘urge to try’ and turn this into motivation to try new things, step out of their comfort zone, and explore the unfamiliar.”

(September 2021)

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