Optimizing Comfort Ventilation in Tropical Townhouses: A Simulation-Based Evaluation and Practical Design Framework

Abstract

Small-scale townhouse developments in Bangkok often face natural ventilation problems due to high-density sites and deep-plan building typologies that lack side openings. This study aims to evaluate the comfort ventilation performance of conventional townhouses and climate-responsive townhouse designs using Computational Fluid Dynamics (CFD) simulations based on a real project case study. The evaluation was benchmarked against the ASHRAE 55-2020 standard, using a minimum air velocity of 0.3 m/s as the target criterion. The results reveal key findings at two levels. First, at the layout level, avoiding continuous building rows through staggered layouts and appropriate street proportions can reduce wind-shadow areas and improve airflow penetration into the site. Second, at the building level, subtractive massing to create side openings can transform single-sided ventilation limitations into cross-ventilation opportunities. In addition, a centrally located permeable staircase can function as a vertical ventilation shaft. The proposed framework can be applied to extend the comfort range of townhouse developments and similar residential projects in tropical climates.