The layouts of the buildings we live in shape our everyday lives. In office environments, building spaces affect employees’ communication, which is crucial for productivity and innovation. However, accurate measurement of how spatial layouts affect interactions is a major challenge and traditional techniques may not give an objective view. We measure the impact of building spaces on social interactions using wearable sensing devices. I will first describe work where we study a single organization that moved between two different buildings, affording a unique opportunity to examine how space alone can affect interactions. Then I will illustrate a study of cultural differences in inter building interaction. The analysis is based on deployments of wireless sensing technologies: short-range, lightweight RFID tags capable of detecting face-to-face interactions. The talk is based on works published at ACM CSCW 2014 and ACM Ubicomp 2014.