Hot, cold, or just right? An infrared biometric sensor to improve occupant comfort and reduce overcooling in buildings via closed-loop control

Levinson, Ronnen; Kim, Donghun; Goudey, Howdy; Chen, Sharon; Zhang, Hui; Ghahramani, Ali; Huizenga, Charlie; He, Yingdong; Nomoto, Akihisa; Arens, Edward; Suárez, Ana Álvarez; Ritter, David; Tarin, Markus; Prickett, Robert

doi:10.1016/j.enbuild.2024.114063

Hot, cold, or just right? An infrared biometric sensor to improve occupant comfort and reduce overcooling in buildings via closed-loop control

Journal Article · Tue Mar 05 23:00:00 EST 2024 · Energy and Buildings

DOI:https://doi.org/10.1016/j.enbuild.2024.114063· OSTI ID:2407291

^[1]; Kim, Donghun ^[1]; Goudey, Howdy ^[1]; Chen, Sharon ^[1]; Zhang, Hui ^[2]; Ghahramani, Ali ^[2]; Huizenga, Charlie ^[2]; He, Yingdong ^[2]; Nomoto, Akihisa ^[2]; Arens, Edward ^[2]; Suárez, Ana Álvarez ^[3]; Ritter, David ^[3]; Tarin, Markus ^[3]; Prickett, Robert ^[4]

Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
University of California, Berkeley, CA (United States)
MoviTHERM, Irvine, CA (United States)
Daikin Silicon Valley, Santa Clara, CA (United States)

To improve occupant comfort and save energy in buildings, we have developed a closed-loop air conditioning (AC) sensor-controller that predicts occupant thermal sensation from the thermographic measurement of skin temperature distribution, then uses this information to reduce overcooling (cooling-energy overuse that discomforts occupants) by regulating AC output. Taking measures to protect privacy, it combines thermal-infrared (TIR) and color (visible spectrum) cameras with machine vision to measure the skin-surface temperature profile. Since the human thermoregulation system uses skin blood flow to maintain thermoneutrality, the distribution of skin temperature can be used to predict warm, neutral, and cool thermal states. We conducted a series of human-subject thermal-sensation trials in cold-to-hot environments, measuring skin temperatures and recording thermal sensation votes. We then trained random-forest classification machine-learning models (classifiers) to estimate thermal sensation from skin temperatures or skin-temperature differences. The estimated thermal sensation was input to a proportional integral (PI) control algorithm for the AC, targeting a sensation level between neutral and warm. Our sensor-controller includes a sensor assembly, server software, and client software. The server software orients the cameras and transmits images to the client software, which in turn assesses occupant skin temperature distribution, estimates occupant thermal sensation, and controls AC operation. A demonstration conducted in a conference room in an office building near Houston, TX showed that our system reduced overcooling, decreasing AC load by 42% when the room was occupied while improving occupant comfort (fraction of “comfortable” votes) by 15 percentage points.

View Accepted Manuscript (DOE)

Research Organization:: Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)

Sponsoring Organization:: USDOE Office of Energy Efficiency and Renewable Energy (EERE), Energy Efficiency Office. Building Technologies Office

Grant/Contract Number:: AC02-05CH11231

OSTI ID:: 2407291

Journal Information:: Energy and Buildings, Journal Name: Energy and Buildings Vol. 312; ISSN 0378-7788

Publisher:: ElsevierCopyright Statement

Country of Publication:: United States

Language:: English

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Hot, cold, or just right? An infrared biometric sensor to improve occupant comfort and reduce overcooling in buildings via closed-loop control

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