Combined infrared imaging and structure from motion approach for building thermal energy efficiency and damage assessment

In the United States, buildings' heating, ventilation, and air conditioning (HVAC) systems account for approximately 40% of the global energy consumption, and contribute between 40% and 48% of the CO2 emissions. One of the largest causes for this type of energy consumption is heat loss. Energy loss can be attributed to inefficiency and sub-surface defects in the structure that reduce the thermal resistance and facilitate unwanted heat transmission within the environment. In recent years, infrared (IR) thermography has proven to be an excellent tool for detecting heat loss from a building envelope. At the same time, advancements in computer vision systems have enabled the use of Structure from Motion (SfM) as a photogrammetry technique. SfM is used for the generation of three-dimensional (3D) building information modeling (BIM). It has the potential to facilitate remote visual inspection of large-scale structures and infrastructure systems by creating virtual renderings. The results of an experiment performed on a lab-scale building using both IR and SfM techniques is analyzed. In particular, the accuracy of SfM in generating a 3D virtual rendering of a target object by using images acquired from a low-cost IR camera is discussed. IR images of a building are recorded and are used for reconstructing a digital model of the structure. The goal is to characterize the viability of SfM in detecting sub-surface defects that can yield to significant heat loss and reduce thermal efficiency in the façade of the building.