Internal insulation retrofit with ventilated wall and circulation of dry air – focus on airflow distribution and mitigation of noise

¹ Department of Civil Engineering, Technical University of Denmark, Brovej building 118, DK-2800, Kgs. Lyngby, Denmark
² Saint-Gobain Nordic, Robert Jacobsens Vej 62A, DK-2300, Copenhagen S, Denmark

^* Corresponding author: cah@byg.dtu.dk

Abstract

External façade retrofit changes the look, feel and aesthetics of the building and internal façade retrofit changes the heat and moisture conditions of the existing façade. The ventilated internal insulation wall is an existing solution for internal retrofit applications that promises to be an efficient and moisture resilient retrofit solution. It has a ventilated cavity and the moisture content in the cavity is actively controlled by a small dehumidifier unit mounted in the wall. The dehumidifier circulates air inside the air cavity and any excessive moisture is ejected into the room air. The focus of the paper is on mitigating noise from the dehumidifer by analyzing the required airflow rate, the air distribution inside the air cavity as well as optimizing the dehumidifier. CFD simulations were carried out to analyze airflow velocities and distribution and the final results show a possible 30% reduction in the airflow rate without compromising the drying performance. In addition, experimental studies in noise mitigation were performed. Different dehumidifier designs with different fan configurations were tested. A significant noise reduction was obtained from 39 dB(A) to a noise level of approx. 26 dB(A).