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

Christian A Hviid,Fabricio Lucchesi,Dessy Wina Harjani

doi:10.1051/e3sconf/201911106066

Christian A Hviid, Fabricio Lucchesi + Show 1 more

Open Access

https://doi.org/10.1051/e3sconf/201911106066

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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).

Highlights

Internal insulation is problematic in heritage buildings because they are often made from combinations of wood and stone materials
The old façade is exposed to moisture from both inside and outside which may cause moisture build-up, and subsequent decay, fungi growth and rot of any organic materials [1]
The dehumidifier has the important role of ensuring adequate circulation of air in the cavity between the original wall and the extra wall layers in order to avoid the build-up of moist

Summary

Introduction

Internal insulation is problematic in heritage buildings because they are often made from combinations of wood and stone materials. The basic idea is to apply extra wall layers to the original (existing) wall to improve the insulation properties. The dehumidifier has the important role of ensuring adequate circulation of air in the cavity between the original wall and the extra wall layers in order to avoid the build-up of moist. The dehumidifier is of a desiccant type which is suitable for use in the winter time for areas with low temperatures and high relative humidity (RH) like in Denmark. This solution is acceptable for commercial buildings, but for residential use, the solution generates too much noise. The air distribution ductwork and the layout influences the noise level due to its impact on the air flow

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