A Dual Airflow Window for Indoor Air Quality Improvement and Energy Conservation in Buildings

This paper proposes a novel dual airflow window for use in residential buildings that tempers outdoor air with exhausted indoor air. The energy needed to condition outdoor air is reduced because of the counterflow heat exchange between the two flow streams. Experimentally validated computational fluid dynamics (CFD) simulations have been used to optimize the window design and to estimate the benefits of the window system. The results show that a small flow rate of 10 L/s and a small cavity width of 9 mm result in the best window performance. The heat recovery efficiency of the window varies from 20 to 56% under the conditions studied in this paper. Within this range, the utilization of trapped solar energy can account for up to a 20% improvement in efficiency during winter conditions. The performance of the dual window is better than that of the existing single airflow window. Although the study shows risk of condensation under humid conditions, the dual airflow window has a great potential for conserving energy and improving indoor air quality.