Grantee Research Project Results
Final Report: Human-Building Integration: Occupant Eye Pupil Size-Driven Lighting Control As a Sustainable Indoor Environmental Control Strategy in a Built Environment
EPA Grant Number: SU839276Title: Human-Building Integration: Occupant Eye Pupil Size-Driven Lighting Control As a Sustainable Indoor Environmental Control Strategy in a Built Environment
Investigators: Choi, Joon-Ho , Schiler, Marc , Lin, Xiaoxin , Wolfe, Bernadette , Ferguson, Kody
Institution: University of Southern California
EPA Project Officer: Page, Angela
Phase: I
Project Period: January 1, 2018 through December 31, 2018
Project Amount: $15,000
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet (2017) RFA Text | Recipients Lists
Research Category: P3 Awards , Sustainable and Healthy Communities , P3 Challenge Area - Sustainable and Healthy Communities
Objective:
The purpose of this project is to develop an individual user’s eye-pupil size data-driven adaptive lighting environmental control module that will accomplish energy savings in a building lighting system operation and cost-effectively control a visual environmental condition. Considering that an office building’s occupants are not responsible for utilitycosts and, thus, tend to be less responsive to the need to conserve energy than in a residential setting, this project focuses on an office building workplace to establish an energy-efficient building environmental control. The following specific research objectives have been established in order to reach this project goal:
1) Understand the relationships between human physiological signals (i.e., pupil size and the ambient environmental condition (i.e., lighting) with consideration of subjects’ ethnic origin and age.
2) Develop stochastic models of visual sensations as a function of human physiological signals to be combined with an end-user level lighting environmental control.
3) Integrate the developed stochastic models to enable the deployment of the lighting environmental control in a building energy management system.
4) Evaluate the effect of a human-based lighting system’s control of occupants’ visual sensation estimations in relation to building energy performance.
Summary/Accomplishments (Outputs/Outcomes):
As an early study, this research conducted a human subject experiment with twenty subjects in an environmental chamber and investigated the differences in pupil sizes caused by various visual sensations due to different contrast ratios and unified glare ratings (UGR) values. Overall, significant differences in pupil sizes in response to various visual sensations could be identified when grouped by contrast ratio as well as by UGR value. These findings indicated that pupil size has the potential to be a viable indicator of preferred lighting conditions. For each contrast ratio group, the adjustment range of pupil size was always greater in the dark, as compared to a bright environment. Compared to three contrast ratio groups, the data showed that the adjustment range of pupil size reduced as the contrast ratio narrowed down between a backlighted and task screen. The amplitude range was relatively minimal when the backlight was turned off. The adjustment range of pupil size was significantly greater in the dark, than in the other two groups, whenthe contrast ratio was 1/4.25. This also happened in the groups when the UGR value equaled 18.1 (which was very close to the upper limit value of 19). The eye requires a greater range of adjustment of the sphincter to achieve the proper pupil size, which may be one of the factors leading to eye fatigue. Also, there is no statistically significant difference between the 1/1 contrast ratio and the6.4/1 contrast ratio group. Therefore, the recommended value mentioned in chapter 2.2 has a certain rationality based on the discussion above.
Conclusions:
This research dealt with the relationship between human visual sensation and environmental lighting conditions, based on an occupants’ physiological responses when detecting (im)proper ambient lighting schemes. Illuminance, contrast ratios, and unified glare ratings were tested to identify which is the most significant technical lighting parameter that affects a user’s visual comfort and satisfaction perception. This study also confirmed that illuminance is a primary driving factor of lighting conditions that significantly affects visual comfort and that an optimal control strategy would contribute to saving the use of lighting energy by up to 55%. For verification of the developed biosensing environmental control, a prototype control module was developed in a lab setting to enhance its technical features while considering a real environmental setting. This included offices and educational facilities, where the lighting environment could affect the user’s productivity and environmental health, as well as building energy performance. Further research is deemed essential and is requested to further improve and verify the proposed Human-Building Integration research principle in real practice.
Journal Articles:
No journal articles submitted with this report: View all 2 publications for this projectSupplemental Keywords:
Smart control; Energy use optimization; Visual comfort; Energy savings; Human-in the loop; User-centered environmental control; Resilient cyber-physical systemRelevant Websites:
Human-Building Integration Lab Project Website Exit
First- and Second-Year Studios Utilize LA as Foundation for Housing Projects Exit
The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.