Surface Energy Balance of Green Roofs Using the Profile Method: A Case Study in South Korea During the Summer

This study introduces the profile method as a simple and less expensive approach for estimating the surface energy balance of green roofs, addressing the limitations of costly monitoring systems based on measurements at two vertical points. Four separate experiment buildings were constructed to minimize temperature disturbances: concrete, highly reflective painted, short bamboo, and grass-roofed. This setup allowed the evaluation of the thermal performance of each roof type without interference from connected building structures. The flux profile method was used to estimate sensible and latent heat fluxes using temperature, atmospheric pressure, and wind speed measurements at two elevations and demonstrated its potential applicability. The results showed that the sensible heat flux was highest (103.81 W/m2) for the concrete roof and that the latent heat flux was highest (53.28 W/m2) for the short bamboo roof. These results indicated the reliability of the method in estimating fluxes across all roof types, where the Nash–Sutcliffe efficiency was 0.90 on average. Furthermore, sensitivity analysis showed that the optimal values of albedo and surface roughness for each roof type were within reasonable physical ranges, providing additional validation for the flux profile method. The surface energy balance analysis of green roofs indicates that the profile method could serve as an effective tool for quantitatively evaluating the advantages of green roofs, especially in reducing urban heat island effects and lowering building energy consumption.