Measuring the exitability of buildings: A new perspective on indoor accessibility

In the last decades, geographers’ attention has been drawn to the vertical dimension of space and indoor environments due to population growth and concomitant city expansion. While traditional geography has long studied merely horizontal relationships of spatial processes and phenomena, recent years have also witnessed a growing number of studies that have sought to extend traditional spatial analysis tools to three-dimensional and indoor environments. In line with these developments, this paper proposes a new indoor accessibility measure which quantifies the quality of access to exits, called exitability. In this, the movement of people with respect to its three-dimensional environment, the user characteristics and the surrounding occupant interactions is considered key. Since the accessibility of exits is most important during evacuations, the calculation of exitability uses existing evacuation flow models. In a case study, we demonstrate the usefulness of exitability measurements through an application on existing building data.

► Exitability defines the quality of access to exits in buildings during evacuations.
► The movement of building occupants is the key factor in the calculation.
► The calculation is based on evacuation flow models.
► A case study on an existing building proves the usability of the model.
► Results allow thorough evaluation of inter-room differences in exitability.