A mechanical–optical coupling design on solar and thermal radiation modulation for thermoregulation

Abstract

Passive daytime radiative cooling (PDRC) and selective solar absorption (SSA) represent sustainable alternatives to conventional air conditioning, offering energy-efficient thermal management. PDRC promotes sub-ambient cooling, whereas SSA supports heating, both operating at minimal energy costs. Traditional static PDRC and SSA systems, however, often fail to deal with dynamic and unpredictable environmental temperature fluctuations, leading to overcooling or overheating. In this work, we introduce a novel approach to address these challenges by utilizing a mechanical–optical coupling mechanism for synchronous solar and thermal radiation modulation. This system features a multi-layer structure inspired by the dynamic skin of a squid, composed of a thickness-sensitive Styrene Ethylene Butylene Styrene thermal emitter, an Al₂O₃ bonding layer, an Ag reflector layer, and an Al₂O₃ protective layer. As a result, we successfully achieved a maximum solar modulation of 0.72 (solar reflectance from 0.97 to 0.25) and a thermal modulation of 0.3 (thermal transmittance from 0.07 to 0.37). This innovative modulation enables our film to adjust the temperature by up to 9.3 °C during the day and 2.9 °C at night. Our design significantly reduces annual energy consumption by 20.4% to 56.7%, illustrating a viable and scalable solution for dynamic thermal management suitable for diverse outdoor environments.