This lecture by the instructor focuses on modeling the energy demand in the service sector, which accounts for a significant portion of final energy consumption in industrialized countries. The lecture covers the delineation of the service sector, characteristics of activities and buildings, energy uses, information gathering methods, and forecasting long-term energy demand. It also discusses the impact of building size, age, and features on energy consumption, as well as the selection of technologies to satisfy energy demands. Examples from the USA case are used to illustrate the concepts presented.