Work

Performance assessment methods and metrics for passive daytime radiative cooling materials

Year: 2026

Type: article

Abstract: Passive daytime radiative cooling (PDRC) is an emerging, electricity-free cooling approach that can achieve sub-ambient temperatures by emitting thermal radiation through the atmospheric transparency window (8–13 μm). It therefore offers a promising route to mitigate the growing demand for cooling across a broad range of applications. As the number of reported PDRC materials and demonstrations increases rapidly, robust and broadly comparable figures of merit (FoMs) and testing protocols are increasingly needed to assess performance and to translate laboratory results to diverse outdoor conditions. However, commonly used FoMs and experimental methods are often reported inadequately or without key experimental information, which hampers reproducible benchmarking and cross-study comparison. This perspective critically reviews the main classes of spectral and thermally derived FoMs. In doing so, it discusses numerical and experimental testing approaches by highlighting recurring limitations that drive discrepancies between studies. Building on this analysis, we propose a metrological framework for the classification and comparison of PDRC materials and provide a minimum reporting checklist to enable efficient inter-laboratory comparison and more reliable performance assessment.

Source: Cell Reports Physical Science

DOI: 10.1016/j.xcrp.2026.103225

Authors: Jérémy Werlé, David Tichý, Chrysanthi Efthymiou, Margarita-Niki Assimakopoulos, Michal Voldán, Lorenzo Pattelli

Institutions: Istituto Nazionale di Ricerca Metrologica, Český metrologický institut, National and Kapodistrian University of Athens

Language: English

Topic: Thermal Radiation and Cooling Technologies

Subfield: Civil and Structural Engineering

Field: Engineering

Domain: Physical Sciences

SDG: Affordable and clean energy

Open Access status: gold

Estimated APC paid: $5,620