What the People are Within, the Buildings Express Without: Understanding Facility-Use Variability on a Global Scale

The objective of the Population Density Tables (PDT) project at Oak Ridge National Laboratory (ORNL) is to report building occupancy estimates (per 1000 ft²) on a global scale. Understandably guided by our own cultural perceptions and biases, the greatest challenge in estimating building occupancy is accurately understanding and representing the variability in how people use space, to include both physical structures, as well as surrounding outdoor/semi-sheltered areas. The utilization of space is not uniformly driven by the same factors equally across the globe, as it is directly impacted by a multivariate range of factors including the environment, culture, and socioeconomic inequity. Primarily a quantitatively driven system, PDT is increasingly incorporating more qualitative data to help aid in this understanding - resulting in a more robust interpretation of building occupancy. The aim of the research presented here - focused on understanding the variability of school facilities and their use - is to determine if there is culturally-patterned, predictable use of outdoor/semi-sheltered areas, and, if so, whether incorporating these spaces significantly changes the resulting occupancy numbers reported in PDT. To accomplish this goal, multiple variables - including building area - are input into the PDT system, establishing effective day, night, and episodic occupancy estimates for more than 55 facility-types on the national and sub-national scales. Building area is currently calculated through the analysis of satellite imagery, oblique photographs, and open-source information, which in turn is translated into a digitization of physical structures - rendered within a GIS environment - providing a specific value for building area. Prior to this research, area calculations have been restricted to physical building structures alone. Although not previously considered when calculating building area for PDT, adjacent outdoor or semi-sheltered areas may be used with enough frequency to warrant further analysis and incorporation into occupancy calculations. As there are areas of the globe - identified through qualitative research - that utilize outdoor space to a greater degree, incorporating this cultural data may be used to inform and refine existing population models within the PDT learning system.