Natural ventilation potential for residential buildings in a densely built-up and highly polluted environment. A case study

The application of Natural Ventilation (NV) as a measure to improve comfort conditions in transition and summer periods has been a topic of research on the spotlight for years. However, there is a lack of knowledge about how the combined effect of a dense urban layout with high pollutant concentrations may affect its potential. This paper addresses this gap by running detailed thermal simulations for a typical apartment flat located in the Yuzhong district of Chongqing city (China) using a holistic approach that makes use of: i) wind pressure coefficients on building facades from urban-scale CFD simulations, ii) hourly measured values of PM2.5 concentrations and weather variables and iii) indoor environment measurements for validation purposes. Scenario analysis revealed the average amount of air change rates achievable in a year varies from 8 to 15 ACH according to the windows orientation. These figures drop down to around 2 ACH when taking into account reduced windows opening time when outdoor PM2.5 concentrations are too high. The resulting natural ventilation potential of the case study decreases from 4234 h when outdoor pollution is neglected to 2707 and 529 h when considering the exposure thresholds set by the Chinese government and the WHO respectively.