This project proposes a technique, called the Green Room method, to enable incorporating a Green Façade into a whole building energy model using software from Integrated Environmental Solutions, called Virtual Environment (IES-VE). The technique sees a room created onto the exterior walls of a building. This room has geometry similar to that of a planned or actual Green Façade and sees thermal properties assigned to its walls which are also similar to the ones of the vegetative cover growing on the structure of Green Façades. In addition, a mechanical system is assigned to the void space of the green room (plenum) in order to dissipate the thermal gains from solar radiation through evaporative cooling, imitating plant transpiration and other biological functions. Results indicate that the Green Room Method is accurate in predicting the thermal behaviour of Green Façades.