Optimizing wind-catching butterfly roofs to improve cross natural ventilation performance in apartment buildings

Abstract

Abstract This study aims to enhance cross natural ventilation performance in multi-level double-loaded apartments by employing a wind-catching butterfly roof, specifically designed for apartments with a center-to-center opening configuration. A 2k full-factorial design of experiment (DOE) method with a center point is utilized for design optimization. Nine configurations, determined by roof height h and roof angle α, are assessed using Computational Fluid Dynamics (CFD). After the initial DOE assessment, three additional butterfly roof designs with varying α values are explored. The dimensionless flow rate (DFR) serves as the objective function for optimization. The optimal design features a butterfly roof with h = 0.01m and α = 30°, demonstrating improvements of 2.5%−4.9% in DFR and 5.3%−9.0% in the pressure coefficient C p compared to scenarios without a butterfly roof. Butterfly roofs also increased the velocity magnitudes in the rooms of the leeward block, with configurations h = 0.01m and α = 35° and 37.5° showing the most significant increases of 58.5% − 86.9% on levels 1 to 3. The discharge coefficient C d induced by all butterfly roof configurations are within 0.6 − 0.7 on levels 1 to 3, while the C d values for levels 4 to 6 are within 0.5 − 0.6. Although butterfly roofs can enhance indoor air quality, they require further research to meet all recommended guidelines. These findings provide valuable insights for architects and urban planners aiming to reduce the environmental footprint of apartment buildings. This research presents a comprehensive evaluation of the potential of butterfly roofs to enhance apartment ventilation and offers recommendations for future design improvements.