Speaker: Jyotirmoy Mandal Ph.D., University of California, Los Angeles
Title: Radiative Cooling Under the Earth’s Glow
Abstract: Passive radiative cooling (PRC) of objects involves radiative heat loss into the cold outer space through the long wavelength infrared (LWIR) atmospheric transmission window. Due to its passive operation and net cooling effect, it is a promising alternative or complement to electrical cooling. For efficient PRC of objects, an unimpeded view of the sky is ideal. However, the view of the sky is often limited – for instance, the walls of buildings have > 50% of their field of view subtended by the earth, while low-lying roofs are overshadowed by taller buildings. Moreover, objects on earth become heat sources under sunlight. Therefore, buildings with hot terrestrial objects in view experience reduced cooling or even heating.
We show that by using common materials with selective LWIR emittances, walls and roofs can radiatively cool to considerably lower temperatures than achievable by using traditional broadband emitters like paints. Cooling enhancements (theoretical and demonstrated) achieved by such materials opens opportunities for the appropriate selection and design of materials for building envelopes.
Bio: Jyotirmoy “Jyoti” Mandal received his Ph.D. from Columbia University in June 2019, where he created high-performance and low-cost solar heaters and radiative coolers for, and designs that can switch between heating and cooling modes. Currently, he is a Schmidt Science Fellow at University of California, Los Angeles. There, as a postdoctoral researcher in the Aaswath Raman group, he is creating optical components and radiative cooling designs. Besides scientific novelty and performance, a guiding consideration for his designs was low-cost and simplicity of fabrication needed for use in developing countries. Besides radiative cooling and optical design, his interests include photonics of disordered materials, climate science and geoengineering, and sustainable building design.
For more information about joining in remotely, contact Leah Abraha at labraha@gc.cuny.edu