Energy Information Systems (EIS), which can monitor and analyze building energy consumption and related data throughout the Internet, have been increasing in use over the last decade. Though EIS developers describe the capabilities, costs, and benefits of EIS, many of these descriptions are idealized and often insufficient for potential users to evaluate cost, benefit and operational usefulness. LBNL has conducted a series of case studies of existing EIS and related technology installations. This study explored the following questions: (1) How is the EIS used in day-to-day operation? (2) What are the costs and benefits of an EIS? (3) Where do the energy savings come from? This paper reviews the process of these technologies from installation through energy management practice. The study is based on interviews with operators and energy managers who use EIS. Analysis of energy data trended by EIS and utility bills was also conducted to measure the benefit. This paper explores common uses and findings to identify energy savings attributable to EIS, and discusses non-energy benefits as well. This paper also addresses technologies related to EIS that have been demonstrated and evaluated by LBNL.