Effects of vertical farming on natural ventilation of residential buildings

Abstract

While vertical farming can promote sustainable living and mitigate urban heat island, vegetation could worsen the cross natural ventilation due to additional drag force on air flow. This study aims to investigate the impact of vertical farming on ventilation performance that is important to the thermal comfort especially at tropical/subtropical cities. The Computational Fluid Dynamics (CFD) simulation was first validated against the wind tunnel experiment in the street canyon with tree planting. The vegetable was modelled as porous medium in CFD simulation. In the parametric study, six configurations of facades module were investigated with respect to the vegetable block ratio, arrangement, and vegetable species. The results indicate that the natural ventilation performance is highly affected by the block ratio of vegetable. When three forth of the façade is covered by vegetable, i.e. block ratio of 0.75, the natural ventilation of the façade is very limited, with minimum leeward wind speed of 0.2m/s for incoming air flow of 2.0m/s. For the façade with a block ratio of 0.5, half of incoming air flow, i.e. minimum wind speed of 1.0m/s, can reach the near field downstream of the façade to promote indoor thermal comfort. Therefore, in the design process of the vertical farming, the block ratio of vegetable should be carefully determined regarding the ventilation performance. Furthermore, the natural ventilation with the same block ratio of vegetable could also be improved by appropriately modifying the vegetable arrangement and vegetable species. This study provides important understandings on vertical farming to enable architects to make the evidence-based decision in the architectural design.