Conventional cooling systems such as air conditioners should be replaced, because they consume a substantial amount of energy and cause environmental pollution. In this context, radiative cooling systems are emerging as an alternative, as they perform cooling without consuming energy or causing environmental pollution. However, most radiative coolers explored thus far include metals such as silver used as solar reflectors, thereby entailing problems in terms of practicality, mass production, cost, and light pollution. In this study, obtaining clue from seashells, we propose micro-particle-based radiative cooling based on calcium carbonate (CaCO3), i.e., the main component of seashells. This approach utilizes the high-energy band gap of CaCO3 for high-performance radiative cooling. As the cooler has only a single layer of a CaCO3 composite without any metal reflector, it is mass-producible, cheap, and does not cause light pollution. To demonstrate the cooling performance of the CaCO3-based radiative cooler, its optical properties and temperature changes are measured and compared with those of commercial white paint. As a result, it is demonstrated that the CaCO3-based radiative cooler has a cooling power of 93.1 W/m2 and can lower the temperature by an average of 6.52 ℃ and 3.38 ℃ under ambient temperatures in daytime and nighttime, respectively. Therefore, it can be used as a radiative cooler throughout the day.
Bibliographical noteFunding Information:
This research was supported by Creative Materials Discovery Program through the National Research Foundation of Korea (NRF) funded by Ministry of Science and ICT ( NRF-2018M3D1A1058997 ). This work was supported by the National Research Foundation of Korea(NRF) grant funded by the Korea government ( MSIT ) (No. 2020R1A2C3006382 ). This research was supported by the International Research & Development Program of the National Research Foundation of Korea (NRF) funded by the Ministry of Science and ICT (Grant number: 2019K1A47A02113032 ) We would like to thank Editage (www.editage.co.kr) for English language editing.
- Atmospheric transparency window
- Broadband mid-IR emitter
- Passive cooling
- Radiative cooling
ASJC Scopus subject areas
- General Materials Science
- Mechanics of Materials
- Materials Chemistry