Demonstration and Cost Analysis of an Acoustic Building Infiltration Measurement System
Dr. Ralph Muehleisen | Argonne National Laboratory
Objectives of the Demonstration
The overall objective of this project, EW-201719, is to demonstrate and estimate cost-benefits for using SonicLQ, an acoustic building infiltration measurement system (ABIMS), to estimate infiltration rates of military base buildings and locate and size specific leaks. ABIMS uses sound waves to both locate and size leaks in buildings with one measurement which will both speed up building envelope leak detection and location and help prioritize the sealing of the leaks to meet infiltration requirements. Sealing buildings will save the Department of Defense (DOD) money and reduce its carbon footprint by decreasing the energy used for heating and cooling and also will decrease vulnerability to Chemical/Biological/Radiation (CBR) attacks, improve indoor air quality, and reduce damage due to moisture accumulation by reducing uncontrolled air infiltration. The proposed demonstration will compare the accuracy of sizing and locating leaks through comparison to standard blower door and infrared (IR) imaging measurements, and also compare the time and associated costs required to complete tests with SonicLQ and the conventional systems. The demonstration will quantify the ability of SonicLQ to reject background noises common to DOD sites and the ability for the technology to measure leaks while the building is in normal operation (i.e. personnel entering/leaving the building).
SonicLQ uses Nearfield Acoustic Holography (NAH) to measure the propagation of sound through a building envelope. A loudspeaker is placed inside a building and produces sound which propagates through the building envelope where it is measured by a microphone array located outside the building. NAH allows measurement of both the pressure and the velocity of transmitted sound which allows the instrument to separate sound propagated through structural vibration from sound transmitted through air leaks and also to locate and size the leak. The ratio of the acoustic pressure difference between the inside and outside to the velocity is related to the size of the leak, and so with ABIMS an envelope leak can be both located and sized with a single measurement. The blower door is one current state-of-the art for envelope leakage measurement that can quantify the total equivalent air leakage for an entire building but cannot locate or quantify the size individual cracks and cannot be used when people are entering and leaving the building. IR cameras can be used to locate leaks when there is a significant temperature difference between the building interior and exterior, but cannot quantitatively size the leak.
If the test is successful, SonicLQ will have been proven to be an alternative to blower door and IR image testing of building infiltration that will be faster, can be utilized when the building is in use, and that provide more actionable information for leak sealing than conventional testing. This will allow the DOD to test more buildings and obtain more actionable information about building envelope air leaks to reduce the costs and improve the effectiveness of envelope air sealing retrofits.