Experimental validation and impact analysis of dynamic energy exchange between building and rooftop greenhouse (part 1)

Rooftop greenhouses (RTGs) integrated with buildings offer a dual benefit of reducing urban carbon emissions and improving overall energy efficiency through dynamic heat exchange between the two systems. This study aims to experimentally validate and analyse the quantitative impact of dynamic energy exchange between an RTG and its host building by coupling Computational Fluid Dynamics (CFD) and Building Energy Simulation (BES) models based on field experiments at a rooftop greenhouse–office testbed in Korea. Natural ventilation was simulated with CFD, and the RNG k–ε turbulence model provided the best agreement with measurements (RMSE = 0.88), representing an 11–17 % improvement over other tested models. Experiments in summer confirmed vertical thermal stratification of 2.8–3.0 °C between upper and lower layers, which was incorporated into a multi-zone BES model. Winter measurements of temperature and energy use were then applied for BES validation. The calibrated model achieved small bias in energy consumption (NMBE: RTG = 2.0 %, Office = 2.1 %), with CvRMSE values of 10.9 % for the greenhouse and 34.2 % for the office zone. Agreement with internal air temperature was strong (R² = 94–98 %; MAE = 0.7–1.7 °C; RMSE = 0.9–2.1 °C), and total energy consumption differed by only 3.6 % for the RTG and 6.1 % for the office. Overall, the validated framework satisfied international protocols and quantitatively demonstrated the energy-saving impact and dynamic thermal interactions between the RTG and the building. These results provide a robust foundation for scenario analyses of energy savings and carbon reduction.