Performance and seasonal trade-offs of passive daytime radiative cooling roofs in European buildings

• A novel method includes spectral emissivity in PDRC performance simulations. • MATLAB–EnergyPlus model spectral emissivity-dependent radiative cooling effects. • Constant emissivity model slightly overestimates building energy PDRC performance. • Cooling energy savings reach up to 75% in Mediterranean residential buildings. • Spectral emissivity-dependent model reduces winter condensation risks. This study presents an advanced methodology for evaluating passive daytime radiative cooling (PDRC) materials, focusing on their spectral emissivity, a wavelength-dependent property often neglected in building simulations. Two modelling approaches were compared: a simplified constant emissivity model within Energy Plus, and a spectral-dependent emissivity model using a coupled MATLAB–EnergyPlus framework. This model improves the accuracy of surface energy balance representation. Simulations were conducted on four residential buildings across Mediterranean climates: a multi-family building in Marseille, a single-family house in Varaždin, a detached houses in Milan and Athens. Comparisons with other passive technologies (green roofs, inverted roofs, and massive roofs) are also presented. Results reveal significant reductions in roof surface temperatures (up to 30 °C). Although constant emissivity models tend to overestimate cooling performance and the differences with the spectral model remained modest (≤3.8 °C). Accounting for material aging, means surface temperature are expected to rise by 3 °C after 5 years and 6 °C after 10 years. In warm climates like Athens, poor-insulated single-story building (surface to volume ratio = 1.11, total specific heat transfer coefficient = 9.16 W/m 2 K) achieves 75 % reduction in cooling energy need but face a 24 % increase in winter heating, resulting in a modest 5.4 % primary energy saving overall. In this case thermal insulation is more effective than PDRC, reducing primary energy use by around 46 %. Spectral modelling also improves thermal comfort predictions and reduces condensation risks in winter. Overall, the PDRC application delivered substantial gains in annual comfort hours (up to 3.6 times greater). The methodology bridges a critical gap between material-level innovation and whole-building energy simulations, offering a robust framework for integrating next-generation cool roof technologies into climate-responsive building design.