Biometeorological indices explain outside dwelling patterns based on Wi-Fi data in support of sustainable urban planning. (December 2017)

• Record Type: Journal Article
• Authors: Reinhart, Christoph F.; Dhariwal, Jay; Gero, Katy
• Is Part Of: Building and environment. Volume 126(2017)
• Page Start: 422
• Page End: 430
• Publication Date: 2017-12
• Subjects: Biometeorological indices -- Outdoor thermal comfort -- Universal Thermal Climate Index (UTCI) -- Comfort simulations -- Wi-Fi scanner; Buildings -- Environmental engineering -- Periodicals; Building -- Research -- Periodicals; Constructions -- Technique de l'environnement -- Périodiques; Electronic journals; 696
• DOI: 10.1016/j.buildenv.2017.10.026
• Languages: English
• ISSNs: 0360-1323

Abstract

Abstract: This study presents a novel approach to validate the capability of biometeorological indices to predict the likelihood of urban dwellers to be outside during midday. Over a period of ten months three Wi-Fi scanners were used in a public courtyard in Cambridge, MA, to record outside dwelling patterns. Based on encrypted MacIDs courtyard attendees could be divided into 16, 000 regulars and 676, 000 visitors. Universal Thermal Climate Index (UTCI) predictions based on a combination of measured microclimatic conditions and mean radiant temperature simulations using ENVI-met were shown to strongly correlate with the number of regulars present during lunchtime with coefficients of determination (R 2 ) of 92% during spring and 70% during summer/fall, respectively. Lunchtime attendance peaked for UTCI values in the thermal comfort and moderate heat stress ranges. In parallel, the probability for regulars to have lunch outside more than doubled during those UTCI conditions and the median lunchbreak length increased from 8 min to 12 min. These findings suggest that UTCI can be used as a reliable environmental performance metric to support the design and preservation of comfortable outdoor spaces. The reported use of public Wi-Fi data can help city governments to better understand – and potentially improve – the use of outdoor spaces while maintaining the privacy of their constituents. Highlights: Wi-Fi data from smartphones was used to study dwelling pattern of 692, 000 individuals in a courtyard in Cambridge, MA. Lunchbreak patterns of 16, 000 regulars correlated with Universal Thermal Climate Index (UTCI) simulations. Attendance peaked for UTCI values in the thermal comfort to moderate heat stress ranges. UTCI is a reliable performance metric for the design of outdoor spaces.