Green fa ades or vertical greenery systems (VGSs) are continuously gaining attention among urbanists for improving the living comfort and energy efficiency in urban areas. However, modeling and simulating the thermal response of VGSs remains a research topic. This paper introduces a novel inverse modeling approach for modeling the thermal response of VGSs on building envelopes. The modeling approach considers the VGSs as a homogeneous layer with apparent thermo-physical properties. The approach optimizes the apparent thermophysical properties by calibrating the inverse model using data generated by a detailed thermal response model of VGS or experimental data. It is shown that the predicted temperature of VGS deviates by less than +/- 1.3 degrees C, while the heat flux on the inner side of the building envelope deviates by less than +/- 0.3 W/m(2) compared to the measured values.