i2Cool's Electricity-Free Cooling Cuts Roof Temperatures by Up to 32.8°C

Hong Kong climate-tech company i2Cool presented field results from a series of school-based passive radiative cooling pilots at the 2026 Global Conference of the International Decade of Sciences for Sustainable Development, held at UNESCO Headquarters in Paris from 15 to 17 July. Across three Chinese schools, the company's electricity-free cooling membranes and coatings recorded roof-surface temperature reductions ranging from 20.1°C to 32.8°C, with one installation cutting indoor temperatures by 8.3°C. The pilots form part of the Fostering Innovation for Resilience and Sustainable Transformation Programme, a UNESCO-endorsed initiative led by City University of Hong Kong under the International Decade of Sciences for Sustainable Development running from 2024 to 2033.

 

How Passive Radiative Cooling Works Without Electricity

 

The core technology reflects a high proportion of incoming sunlight while releasing heat through mid-infrared radiation, a wavelength range that passes largely unimpeded through the atmosphere into space. That combination allows a surface treated with the material to stay cooler than its surroundings without drawing any power, in contrast to conventional air conditioning, which requires continuous electricity to run compressors and refrigerant cycles.

That distinction matters specifically for facilities where air conditioning is unavailable, insufficient or too expensive to operate reliably, conditions common in under-resourced schools and community buildings across parts of Asia and other developing regions. A cooling technology that requires no electricity input and no refrigerant removes both the ongoing operating cost and the infrastructure dependency that air conditioning requires, making it viable in settings where grid electricity access itself may be limited or unreliable.

 

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What the Field Measurements Actually Show

 

The three pilot deployments demonstrate meaningful variation in results depending on application method and site conditions. At Kuzhi Yucai Public Welfare School in Chenzhou, Hunan, approximately 830 square metres of cooling membrane applied to teaching building roofs achieved a maximum roof-surface temperature drop of 21.6°C alongside an 8.3°C indoor temperature reduction, the only pilot reporting an indoor measurement rather than roof-surface temperature alone. At Ren Bishi Red Army School in Miluo, Hunan, over 668 square metres of membrane achieved the largest recorded reduction, 32.8°C at the roof surface. At Beima Primary School in Longkou, Shandong, a partnership with a Towngas volunteer team applied roughly 960 square metres of cooling coating, recording a 20.1°C difference between coated and uncoated roof areas.

That range, from 20.1°C to 32.8°C, likely reflects differences in local climate conditions, baseline roof materials, and whether the product applied was a film membrane or a sprayed coating, variables that matter for anyone assessing how reliably this technology might perform at a new site with different conditions. The indoor temperature figure from the Chenzhou project is the more directly relevant metric for occupant comfort, since roof-surface temperature reduction alone does not automatically translate into a proportional indoor cooling effect depending on a building's insulation and construction.

 

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Why the Programme Pairs Technology With Education

 

Beyond the physical cooling installations, each pilot incorporated STEM and climate education components, letting students engage directly with the science behind passive cooling rather than treating the technology purely as infrastructure. Pairing a physical intervention with educational programming positions schools as both testing grounds for the technology and platforms for building climate literacy among students, a dual function that may help explain why UNESCO-endorsed programmes have gravitated toward school settings specifically as pilot sites.

The FIRST Programme extends beyond cooling technology to include low-cost printed solar films, waste-biomass conversion, and human-powered water purification, framing the four technology areas collectively around several UN Sustainable Development Goals including clean water and sanitation, affordable and clean energy, sustainable cities, and climate action. The programme has built a network spanning more than 45 partner organisations across 25 countries, with pilots conducted or planned across Hong Kong, mainland China, Vietnam and Malaysia.

 

What Comes Next

 

The FIRST Programme and its cooling applications are featured in UNESCO's 2026 report, Science at a Turning Point, which examines how scientific collaboration can help close gaps in access to knowledge and infrastructure across the Sustainable Development Goals. Whether the technology's demonstrated temperature reductions translate into meaningful energy savings and comfort improvements once deployed at greater scale across the programme's expanding international network, and whether the variation in results seen across the three Chinese pilots narrows as the technology and application methods mature, will indicate how replicable this cooling approach proves across the diverse climates and building types the programme is targeting.