Passive directional sub-ambient daytime radiative cooling

Ultrabroadband photonic structures to achieve high-performance daytime radiative cooling.

If properly designed, terrestrial structures can passively cool themselves through radiative emission of heat to outer space. For the first time, we present a metal-dielectric photonic structure capable of radiative cooling in daytime outdoor conditions. The structure behaves as a broadband mirror for solar light, while simultaneously emitting strongly in the mid-IR within the atmospheric trans...

Nanoparticle embedded double-layer coating for daytime radiative cooling

Radiative sky cooling :

Radiative sky cooling reduces the temperature of a system by promoting heat exchange with the sky; its key advantage is that no input energy is required. We will review the origins of radiative sky cooling from ancient times to the modern day, and illustrate how the fundamental physics of radiative cooling calls for a combination of properties that may not occur in bulk materials. A detailed co...

A field investigation of passive radiative cooling under Hong Kong’s climate

This paper discusses the feasibility of cooling using radiation under Hong Kong’s hot and humid climate. Three different designs of a passive radiative cooler were studied in this work. The three designs include non-vacuum, and vacuum with seven potassium chloride (KCl) IR-Pass windows as well as one system with a single KCl IR-Pass window. The coolers were examined during daytime and night tim...

Passive Cooling Technologies