We have been developing methods for objectively grasping influences of service process changes based on human behavior sensing technologies and work records. In this paper, we describe a case study on a building maintenance service. In order to properly evaluate the service process changes, we analyze multi-faceted indices corresponding to the service triangle. Especially, as some indices concerned with “quality of working (QoW),” we tried to measure and quantify the time-allowance during work. As a result, we found the productivity was improved without reducing the service level. We also found an increase in workload per employee was within an allowable range.