Cooling systems account for nearly 20 % of electricity consumption and 10 % of greenhouse gas emissions, globally. With demand for cooling expected to grow tenfold by 2050, and the increasing frequency of extreme heat waves, improving the efficiency of cooling systems plays a critical role in addressing the global climate challenge. Passive Radiative Cooling (PRC) materials that can dissipate heat as infrared radiation have recently emerged. This project aims to develop a comprehensive metrological framework, including standardised performance indicators (i.e. figures of merit) and testing protocols, to enable the comparable evaluation of their cooling performance on-site and determination of the potential energy savings that could derive from the deployment of such technologies.