Optimized Green Walls: Study of Vertical Green Systems’ Performance in an Urban Setting

The construction, operation and maintenance of buildings consume more than 40% of primary energy in most countries. Out of this 40%, a large portion is related to the operational phase involving heat losses through a buildings envelope. To reduce this loss, several materials have been developed to reduce the thermal transmittance through a façade, even though they carry a heavy environmental burden. Furthermore, the unregulated and rapid expansion of urban environments led to a considerable amount of problems. Among them, the urban heat island effect demands special attention as it has been responsible for an increase of the energy consumption to higher mortality rates. In part, the use of materials with high thermal admittance is responsible for these effects. Vertical green systems have shown to be a potential solution to improve, among others, the thermal demands of buildings and to mitigate the urban heat island effect. However, due to the uncertainty associated with their design process and operation, the implementation of vegetation as a construction material in an urban setting is often overlooked. Therefore, an in-depth study of their performance under different configurations and climate conditions is needed. The optimization study was based on the parametrization of a green façade and a living wall system which aimed to identify their response under variable initial conditions. A analysis of the essential parameters in the vegetation model was performed. Consequently, the leaf area index showed the highest effect, followed by the substrate thickness, leaf angle distribution, leaf surface albedo and finally by the moisture content of the substrate layer. Furthermore, a state-of-the-art computational work flow was developed through the integration of ENVI_met, Rhino/Grasshopper and modeFRONTIER, in combination with Python 3 scripting, to evaluate the performance of vertical greenery systems. The evaluation focused on the heat transmission through t
Civil Engineering | Building Engineering