Instantaneous and Long-term Lighting Design Metrics for Higher Education Buildings in a Tropical Climate Zhe Kong 1 , J. Alstan Jakubiec 2 1 Southeast University, Nanjing, China 2 University of Toronto, Toronto, Canada Abstract This paper presents a study that explores instantaneous and long-term lighting design metrics based on subjective evaluations within higher educational buildings in a tropical weather. Three types of classrooms–computer labs, collaborative spaces, and lecture halls–were studied. Lighting simulation models were calibrated and validated using measurements taken onsite and utilized to generate both instantaneous and annual climate-based lighting predictors. Four hundred and thirty-nine participants’ responses to online questionnaires were collected. From an analysis of this data, the authors recommend instantaneous horizontal illuminance of 150 lx and vertical illuminances of 200 lx as the lighting thresholds for classrooms access to daylight, which result in 80% of occupants reporting imperceptible or noticeable daylight glare, as well as 53% of occupants comfortable with daylighting environments. Annual mean vertical illuminance of 200 lx during the daytime leads to 85% of occupants satisfied with annual access to daylight. Daylight falling on monitors should be controlled around 100 lx or lower to satisfy at least 70% of occupants and reduce reflections in monitors. For classrooms under electric lighting, horizontal illuminance of 200 lx and vertical illuminance of 250 lx are recommended to achieve visual comfort for 60% of occupants and visual discomfort for 7% of occupants. Introduction Lighting has an important impact on comfort, learning, and task performance as has been alluded to by many researchers. Heschong et al. (2002 and 2007) demonstrated the improvement of students’ performance associated with sufficient and uniform daylight and later proposed the positive correlation between student performance and horizontal illuminance under daylight. Theodorson (2009) demonstrated the importance of daylight from teachers’ perspectives. Dunn et al. ( 1985) suggested designing lighting environments according to an individual’s needs. Although many studies have demonstrated lighting’s positive influence on student performance, insufficient research explores lighting design thresholds from the occupant’s perspective in educational spaces. Instead of employing the same visual discomfort and lighting design thresholds for all countries and contexts, recent research has shown that occupant preferred lighting levels are influenced by the climactic context. Although Wienold et al. concluded Daylight Glare Probability (DGP)’s highest performance in lab studies globally (2019), Mangkuto et al. (2017) suggested much lower Daylight Glare Probability (DGP) thresholds for detecting results from perceptible to intolerable glare in Indonesia. Hiring et al. (2017) proposed the ratio of window to background luminance as the more sensitive measure of occupant discomfort under tropical skies. Dahlan et al. (2009) concluded that participants accepted dimmer daylighting environments in Malaysia. These previous studies show the necessity of exploring daylighting design metrics under tropical skies for educational facilities. Despite the fact that many studies focusing on instantaneous lighting metrics (Hirning, Isoardi, & Garcia-Hansen, 2017; Jakubiec, Reinhart & Van Den Wymelenberg, 2015; Van Den Wymelenberg, 2012; Wienold & Christoffersen, 2006) limited studies have explored long-term lighting metrics. Wienold proposed a simplified method of calculating annual DGP and defined the annual daylight glare comfort classes without subjective assessments (Jan Wienold, 2009). Similarly as Useful Daylight Illuminance (UDI) (Nabil & Mardaljevic, 2006) and Daylight Autonomy (DA) (Reinhart, Mardaljevic, & Rogers, 2006; Reinhart & Walkenhorst, 2001), Spatial Daylight Autonomy & Annual Sunlight Exposure (IES-LM-83, 2012) proposed annual climate- based metric of avoiding direct sunlight without further proof involving occupant subjective evaluations. Jakubiec and Reinhart (2016) proposed an annual discomfort glare model specific to the site and participants in their study. Rockcastle and Andersen (2014) suggested image- based annual spatial contrast and annual luminance variability as a metric by simulating ten conceptualized spaces without subjective evaluations. This study aims to fill the gap by combining detailed physical measurements, correlations with occupant subjective data on perception, and an investigation of instantaneous and long-term simulation metrics used in design. This research investigates lighting metrics within three types of classrooms in Singapore. Lighting data within 12 classrooms were measured or simulated. Four- hundred and thirty-nine participants evaluated their instantaneous and long-term lighting experience within the 12 classrooms. One aim of this paper is to examine the effectiveness of existing lighting design metrics in terms ________________________________________________________________________________________________ ________________________________________________________________________________________________ Proceedings of the 16th IBPSA Conference Rome, Italy, Sept. 2-4, 2019 1083 https://doi.org/10.26868/25222708.2019.210728