Global assessment of radiative cooling and low-emissivity coatings for energy efficiency in buildings across all climate zones

Radiative cooling and low-emissivity coatings are promising strategies for building energy savings. Despite their potential, comprehensive assessments across diverse climate zones remain limited. This study addresses this gap by investigating the potential energy performance associated with these coatings in buildings at 250 locations worldwide, spanning all ASHRAE climate zones. To quantitatively assess the energy efficiency benefits, this study employs EnergyPlus simulations to analyse annual thermal energy needs in two-floor, single-family detached apartments with varying levels of thermal transmittance. Results indicate that radiative cooling coatings provide considerable energy-saving effects for most locations, including those with higher heating demands than cooling demands. For buildings with poor insulation, low-emissivity coatings provide substantial annual energy savings in over 74% of the case locations. Moreover, the study also assesses heating penalties due to overcooling effects, revealing that these are generally less critical than the cooling energy savings in most climate zones. Furthermore, a strong linear correlation was found between yearly energy savings and the annual average outdoor temperature for each coating type in zones 0 to 6. The insights from this study have broad implications for the applicability of radiative cooling and low-emissivity coatings in new constructions and existing building retrofits across various climate zones.