i2Cool: The Coat that Chills
If Dr Martin Zhu had lived in a more modern building as a child, i2Cool and its revolutionary technology might never have existed. As he recounts, “In the summer that type of old building was incredibly hot. You could barely survive in there. Even if you had air conditioning and turned it to maximum, you would barely feel the difference.
“I couldn’t stand it and I really wanted to change my living environment.”
Inspiration from perspiration
The oppressive heat of Zhu’s childhood forged an obsession with cooling that guided his studies all the way to his PhD from the City University of Hong Kong (CityU). But rather than researching ways to improve air conditioning technology, Zhu’s path led him toward a much greater vision; a zero-energy, low cost, super efficient way to passively cool any building – to not necessarily replace air conditioning, but enable us to live comfortably with significantly less.
In other words, a “universal solution” with the potential to disrupt an entire industry ecosystem.
As overambitious as this may sound, various proven technologies and methods for effective passive cooling have long existed. But as Zhu and his colleagues quickly discovered, such films and coatings usually require the use of silver and heavy metals, making them much too expensive to serve as a “universal solution”.
Learning from nature
The beginnings of a breakthrough occurred when Zhu and his fellow researchers crossed paths with the Saharan silver ant. An insect of many extraordinary qualities, it is the fastest of all ant species, travelling at 108 times its own body length per second (if it were human sized, this would correspond to a speed of over 700 km/h). But what specifically inspired Zhu was its amazing ability to go about its business in the 47-degree Celsius heat of the desert. Perhaps this was an ant with answers.
“With the help of biologists, we learned that the structure of the ant’s silvery hairs not only makes them an excellent reflector of solar energy, but also enables them to dissipate body heat as mid-infrared energy,” Zhu explains. “We learned from this working principle and adopted it to our materials.”
At that stage, Zhu and his colleagues had developed a water-based, reflective paint-on coating that, in trials, had proved capable of reducing surface heating by a stunning 30 degrees Celsius. “Nevertheless, we were still using some very expensive materials to simulate the structure of the silver ant – a 10x10cm patch of our material would have cost about HK$20,000. But it did show that what we were doing was feasible,” says Zhu.
Further ant-guided development enabled some expensive ingredients to be supplanted by cheaper ones, and for the paint’s nano structure to be optimised and refined. Eventually, the formula reached the ideal balance of durability, performance and cost – just in time for CityU’s ‘Tech 300’ programme to offer the prospect of commercialisation.
“In that year we came into contact with various industrial partners, government departments such as Invest Hong Kong, and potential clients suggested by the university. It was a great help, because if you are trying to promote a new material, nobody trusts you at first. The government provided us with the means to conduct more real-world testing. Then we started to sell the product using the test data,” Zhu recalls.
Feeling is believing
The data was important, because on the face of it, the i2Cool company’s first product sounds almost too good to be true. The formula is simply mixed with water and brushed on like paint, and can remain effective for up to 10 years before reapplication is needed. As one of i2Cool’s first customers found, it can reduce air conditioning energy consumption by a whopping 42% – paying for itself in less than a year. Not surprisingly, the product has caught on, having since been used on several buildings in Hong Kong (including Central Market) and the mainland.
On a smaller scale, i2Cool collaborated with an NGO to apply the paint to the rooftop of a subdivided apartment block in Sham Shui Po. Residents subsequently reported electricity bills reduced by around HK$150 a month.
As Zhu points out, a widespread use of the paint – even just on roofs – would make a significant dent in one of Hong Kong’s major sources of energy consumption. “It would be very effective in improving the carbon neutrality of Hong Kong, and I think this would also be the case in other cities in the GBA, southern China, Singapore, the Middle East, etc.” He muses.
From roofs to windows to pavements
Rooftops are only just the start. The formula can be easily mixed with polymer-based paints to reduce the air conditioning needs of everything from warehouses to data centres to buses to cruise ships. i2Cool has already applied it to make ceramic tiles and transparent films for windows. “The tiles are suitable for pavements in gardens, playgrounds, etc, and would help solve the heat island issue for the community,” says Zhu.
On that note, the coming year will see i2Cool launch a consumer version of its paint, truly fulfilling its universal potential. And soon, the company will be applying the paint to a large number of rooftops in Sham Shui Po to observe its impact on the heat island effect. “We already found that if you passively reduce the surface temperature of one building, it has an effect on other buildings closely around it,” Zhu remarks.
A Hong Kong that’s cooler outside as well as inside? That’s the kind of disruption Martin Zhu – and all of us – can be comfortable with.