Real-Time Monitoring of Occupants’ Thermal Comfort through Infrared Imaging: A Preliminary Study

Abstract

Thermally comfortable indoor environments are of great importance, as modern lifestyles often require people to spend more than 20 h per day indoors. Since most of the thermal comfort models use a variety of different environmental and personal factors that need to be measured or estimated, real-time and continuous assessment of thermal comfort is often not practically feasible. This work presents a cheap and non-invasive approach based on infrared imaging for monitoring the occupants' thermal sensation and comfort in real time. Thanks to a mechatronic device developed by the authors, the imaging is performed on the forehead skin, selected because it is always exposed to the environment and, thus, facilitating the monitoring activity in a non-invasive manner. Tests have been performed in controlled conditions on ten subjects to assess the hypothesis that the forehead temperature is correlated with subjects' thermal sensation. This allows the exploitation of this quantity as a base for a simple monitoring of thermal comfort, which could later be tuned with an extensive experimental campaign.

Non-invasive (non-contact) measurements of human thermal physiology signals and thermal comfort/discomfort poses -A review

“…Infrared cameras are usually high cost and big size. Oliveira et al, 2007Bouzida et al, 2009Burzo et al, 2014Ranjan and Scott;2016Burzo et al, 2017Pavlin et al, 2017Metzmacher et al, 2018Yoshikawa et al, 2019 Non-invasive measurements (crossvalidation of infrared camera, RGB camera and wearable devices)…”

“…Infrared camera was widely used for collecting and analyzing infrared images of nude skin such as facial, hand skin (Bouzida et al, 2009;Burzo et al, 2014;Ranjan and Scott;2016;Burzo et al, 2017;Pavlin et al, 2017;Metzmacher et al, 2018), which could be used to control HVAC systems in energy efficient manner without influencing thermal comfort (Ranjan and Scott, 2016). Facial skin temperature was obtained by far-infrared imaging (7-14 μm).…”

Skin Temperature Extraction Using Facial Landmark Detection and Thermal Imaging for Comfort Assessment

“…al. utilized a low resolution thermal camera (FLIR Lepton) to extract temperatures from the forehead region and showed that the extracted temperatures were well correlated with thermal sensations [27]. The approach utilized a low-resolution thermal camera however, it was only able to extract crude measurements from the forehead.…”

“…Among the non-intrusive techniques, thermal imaging has been more widely studied. Results from previous studies show that thermal imaging can provide useful information towards predicting thermal sensations [10,23,27,29]. However, previous studies have either manually extracted skin temperatures from different regions of interest (ROI) or utilized automated methods that are not very accurate in extracting skin temperatures from different ROIs using a thermal camera.…”

Automatic HVAC control with real-time occupancy recognition and simulation-guided model predictive control in low-cost embedded system

“…Therefore, there are plenty of opportunities to harness recent embedded system technologies in intelligent building automation systems. Particularly, sophisticated computational tasks can be conducted on these embedded systems efficiently, such as real-time video processing and accurate building thermal response simulation (e.g., [13]).…”