The Design and Assessment of the Hollow Precast Wall with Integrated Active Ventilation System, for Minimizing Heat Retention, Removing Heat Load

Abstract

Cooling demand in hot, humid climates is driven primarily by heat gains through the building envelope, particularly through opaque wall elements. Conventional static insulation systems reduce steady-state heat transfer but are limited in their ability to dissipate stored heat and respond dynamically to transient thermal loads. This study presents a comprehensive assessment of an actively ventilated hollow precast wall system designed to enhance heat removal through low-speed forced airflow within an internal cavity. A coupled analytical and numerical methodology is employed to quantify airflow-dependent thermal resistance, heat flux reduction, and transient thermal response under conditions representative of hot climates. The results demonstrate that introducing very low airflow (approximately 0.1 m/s) increases the effective thermal resistance by about 28% and reduces heat transfer by more than 50% compared with a non-ventilated wall. The most significant performance improvement occurs during the transition from natural to weak forced convection, while higher airflow rates yield diminishing returns. The findings indicate that actively ventilated hollow precast walls can function as low-energy, hybrid passive–active envelope systems with strong potential to reduce cooling loads in tropical and subtropical buildings.

Keywords: Actively ventilated wall; Hollow precast wall; Dynamic insulation; Thermal resistance; Building envelope energy performance.