Buffering practices in HVAC ductwork supply chains

Buffers are important components of production systems. They are necessary holding places for resources needed to perform tasks and to protect production systems against variations in supply and demand. Protecting production systems against supply and demand variation comes at a cost, which can be high in case buffer profiles (i.e., type, location, and size) are not judiciously defined. In this dissertation, the author focused on the heating, ventilation, and air conditioning (HVAC) sheet metal ductwork supply chain (SMDSC) to investigate how companies define buffer profiles. In the SMDSC, one company (i.e., mechanical contractor) may perform all activities (i.e., design, detail, fabricate, install, and maintain) necessary to deliver the final product. This allowed the author to investigate execution of multiple activities in the SMDSC and interaction between different stakeholders. The author visited a group of companies, fabrication shops, and construction sites to investigate buffering and batching practices used and their relationship with these companies' business environment. Three case studies were conducted to investigate the dynamics of fabrication shops in the SMDSC and the relationship between fabrication and installation. This research revealed that buffer profiles appear to be closely related to the business environment in which a company operates. The simulation models presented in this dissertation illustrate the importance of real-time feedback and communication between different activities in the SMDSC and their role in the definition of buffer profiles. Based on these findings, the author discusses alternatives to improve the definition of buffer profiles in the SMDSC as a means of improving this supply chain's performance. This dissertation sheds light on concepts and applications to define buffer profiles as well as to design production systems as needed to improve performance in the SMDSC. The research findings indicate that deeper and further investigation of these topics is warranted, beyond what is presented here.