Passive strategies involving greenery significantly increase energy performance in buildings and comfortable microclimate conditions. However, few studies model and simulate their effect on buildings’ energy performance. Thus, this work assesses modelling approaches for conducting building performance simulations where detached vertical green trellises (DVGT) are included. The DVGT characteristics are modelled by: (i) large solid component blocks and (ii) small opaque solid component blocks to form a grid. A building with glazed façades is evaluated through dynamic simulation under the tropical climate of Panama City, using DesignBuilder. Parametric analysis is performed to study the impact of the trellis configuration on the performance in reducing the annual cooling, lighting, and total electricity consumption. A cost-effective evaluation is also conducted based on the net present value for each trellis configuration. Results showed strong agreement with previous studies reporting significant cooling needs reduction while increasing lighting needs and promising return periods. This concludes that the correct optical and radiative properties of the vegetation layer that are wanted to be modelled in a detached vertical trellis are crucial.