Towards Understanding Productivity in On-Site Housebuilding

Sammanfattning: The construction industry has a problem of defining, measuring and using productivity that seems to have led to suboptimal overall project performance. Previous research suggest that productivity is a multifaceted term, which meaning depends on the purpose of addressing productivity, the context where one uses the term, the level of analysis (e.g. task, project or industry) and even the background or discipline of the one who addresses the term. Such multifaceted meaning appears to have encouraged the development of multiple methods for measuring productivity in construction. Yet, despite the multitude of methods developed for measuring productivity, global reports over the years indicate that productivity development in construction is poor if compared to other industries, even negative in some countries, calling for a change to increase productivity. The variety of understandings of productivity indicate that different aspects of productivity are accounted for by different people. Moreover, the construction productivity measures at different levels account for different things, and there is a lack of a clear connection between the levels of analysis, which indicates that methods and metrics at different levels also measure and represent different things. Subsequently, how to understand construction productivity, and then what or how to measure and how to use the measures of productivity becomes unclear.This thesis furthers how construction productivity in housebuilding can be understood based on how it is defined, measured and used by drawing on how the literature and on-site housebuilding contractors address the term concerning how productivity is defined, measured and used. The research questions of how productivity is understood, how productivity is measured, and how productivity is used by Swedish housebuilding contractors are answered and synthesized to contribute with an enhanced understanding of construction productivity.  Empirical data was collected through 17 semi-structured interviews and four workshops. The interviews were held with practitioners ranging from site-, to project-, to business area managers from one small and four of Sweden’s largest contractors. The workshops were held with senior managers in charge of production development at the four large companies. Data was cross-analyzed to identify commonalities and contrasting findings connected to how productivity can be defined or understood to represent and include, how productivity can and could be measured, and how productivity can be used. The findings suggest that productivity in on-site housebuilding production is about how efficiently the production system reaches the purpose of its existence; its goal. That is, how efficiently the building is produced in conformance with the requirements to meet client values. Hence, productivity in housebuilding production integrates efficiency, effectiveness and many other factors that make the production system function better towards reaching its goal. Yet, what is included in, and thus what productivity represents differs, caused by the choice of level of analysis (e.g. task, project or industry), and the length of the considered system or value chain (e.g. only production, or design, planning and production). The results also indicate that housebuilding productivity includes planning, measurement, control and reporting results. While separate productivity measures can be used in planning and for reporting results, many different measures are applied to understand, enable for and control productivity during operations. These different measures represent different factors understood to influence productivity at different levels. However, the choice of such measures vary, their use is unstructured and the measures usually stay undocumented. The results suggest that one measure of productivity is not enough to understand productivity of building production systems; it is going to be many. There is a need to adopt a systems perspective to understand how to structure and connect the different measures from sub-processes to processes and productivity, which this thesis suggests as a line of future research.