The effectiveness of vernacular stack ventilation with application in modern and retrofitted buildings

Abstract

Ventilation is a vital aspect in an internal environment for every room occupant to achieve basic health requirements and acceptable thermal comfort. To achieve the required ventilation rate, mechanical ventilation is generally used in modern buildings. This comes at an energy cost required in operating the necessary equipment. In some cases, it makes sense to make use of natural ventilation depending on site conditions. Vernacular stack ventilation systems use vents to try to achieve modestly ventilated spaces. At the moment, there is little to no knowledge on their effectiveness and no quantification of the ventilation rates can be found from the addressed literature. This research aims at bridging this gap in knowledge. The ventilation flow rates resulting from vents are numerically assessed using a hypothetical test room as well as a case study. On the basis of this, new modifications are proposed and analysed. The purpose of this is to enhance the ventilation flow rates and compare them with established ventilation standards. The numerical approach used here is based on Computational Fluid Dynamics (CFD). The results obtained are promising, as the studied case was found to result in an air change rate of 3.2l/s or 0.13 ACH for a typical summer condition while the enhanced natural ventilation case produced a ventilation rate of 5.8 l/s or 0.23 ACH, with a significant improvement in comfort. Upon further research, such a vernacular ventilation system using vents could be an important yet simple and relatively maintenance free approach. This can aid in reaching nearly zero energy targets for buildings.