Limited urban ventilation in the case of contemporary perimeter block housing in Poland

Regulating air exchange processes in cities is essential to create spaces conducive to residents’ health and well-being and to make areas resilient to climate change. The widespread trend toward increasing building density risks reducing ventilation efficiency in the vicinity of buildings that form closed spaces. The aim of the article is to diagnose the risk of insufficient ventilation around perimeter building development under the design conditions in force in Poland. The research focused on multi-family residential buildings. A building model was developed using analyses of multi-family block buildings erected after 2003 in three large Polish cities. The study shows that the dimensions of the perimeter building development, especially the w/h ratio of the inner courtyards, resemble parameters recognised in the literature as causing skimming flow and wake interference flow effects. The CFD analysis shows that, for most of the area inside the perimeter building development, the velocity amplification factor does not exceed 0.45. Therefore, the results confirm the risk of insufficient ventilation.