This article is concerned with external ventilation levels within a multi-story Housing and Development Board (HDB) residential estate, focusing toward a deeper understanding of wind flow with respect to different levels of height variation (HV). This study analyzed through parametric study, using numerical simulations with the realizable k – 1 turbulence model, the various scenarios of HV within a typical residential HDB estate or precinct. It is found that external wind flow within the precinct for both the pedestrian and mid-height levels are affected differently by the HV value. Some rules of thumbs can be established for HVs in the efficient use of outdoor ventilation.