Eco-friendly smart daytime radiative cooling coating


Subambient daytime radiative cooling (SDRC) provides a promising electricity- and cryogen-free pathway for global energy-efficiency. This project has led to the development of an eco-friendly, self-cleaning, durable and cost-effective SDRC coating. The coating cools the buildings under direct sunlight in summer without the use of electricity. It can achieve a day-time enhanced yet nighttime suppressed sub-ambient cooling effect.

  • Eco-friendly smart daytime radiative cooling coating 0
  • Eco-friendly smart daytime radiative cooling coating 1
  • Eco-friendly smart daytime radiative cooling coating 2
Commercialisation opportunities
Collaboration for product development, technology development in various application segments; Product distribution
Problem addressed

Building cooling during hot weather is critically important to our society. The peak demands of building cooling in cities pose a great challenge to power grids and may cause power blackouts. Moreover, the refrigerant gases used in air conditioners are one of the largest contributors to greenhouse gas emissions. Environmentally friendly building cooling solutions should be pursued.

  • A unique single-layer daytime radiative cooling coating allowing heat to be transmitted into outer space through Earth’s atmospheric window.
  • The coating has broadband emissivity-induced smart cooling, multiple-layer particle scattering and Purcell effect-enhanced fluorescent emission.
Key impact
  • Collaborating with EMSD and CEDD to perform the field exposure tests to demonstrate the potential of the coating in energy-saving, carbon neutralization and creating sustainable built environment.
  • Winner of 7th "Creation of Youth" Guangdong-Hong Kong-Macao Greater Bay Area Youth Innovation and Entrepreneurship Competition 2021
  • The 7th Hong Kong University Student Innovation and Entrepreneurship Competition (Entrepreneurship, Second Prize)
  • Gold Medal, Special Edition 2022 Inventions Geneva Evaluation Days – Virtual Event”
  • Roof, Wall, In-situ Office, Exhibition hall
  • Industry plant, storehouse, oil tank, airport covered bridge, road


  • PCT patent Application no. PCT/CN2020/124665 Claiming priority from US provisional patent application no. 62/927,756
The Hong Kong Polytechnic University (PolyU)

With over 80 years of proud tradition and ranking among the world’s top 100 institutions, The Hong Kong Polytechnic University (PolyU) aspires to be a leading university with world-class research and education.

PolyU is a home for educating thinkers, discoverers, innovators and communicators in delivering positive impact. We are committed to nurturing tomorrow’s leaders today, through a holistic education that provides graduates unrivaled placements to thrive in communities, industries and businesses.