Investigating the Impact of Architectural Variables on the Optimization of Natural Ventilation in Residential Villas Using CFD Simulation (Case Study: Dastek Region, Gilan)

Abstract

Given the significant contribution of the building sector to global energy consumption—particularly in developing countries like Iran—optimizing natural ventilation has increasingly gained importance as an effective and low-cost solution for reducing energy use and improving indoor air quality. This study aims to analyze the influence of three architectural variables—window-to-wall ratio (WWR), window height, and building orientation relative to prevailing wind—on the performance of natural ventilation in residential buildings. To this end, numerical simulations were conducted using DesignBuilder software and Computational Fluid Dynamics (CFD), and various design scenarios were evaluated across three seasonal climates (spring, summer, autumn, and winter). The findings indicated that increasing the WWR from 40% to 60%, combined with raising the window height to 2 meters, significantly enhances the air ventilation rate (up to 25%) and improves temperature distribution in interior spaces. Moreover, building orientations at angles of 30°, 45°, and +15° relative to the prevailing wind demonstrated the highest effectiveness in increasing pressure differentials and enhancing natural airflow. The results suggest that climate-based smart architectural design can reduce reliance on mechanical ventilation by up to 30%, playing a key role in energy savings, reducing greenhouse gas emissions, and improving the thermal comfort of occupants. This study can serve as both a scientific and practical guide for architects and designers in developing sustainable and energy-efficient buildings.