This chapter describes an owner’s approach to design, install and operate an energy management system (EMS). This approach bucks the multi-vendor “interoperability” trend by standardizing on one EMS system (i.e., one manufacturer). Maintaining a competitive procurement process with one EMS vendor might sound impossible, but the owner’s EMS design approach makes this happen. The ability to design, install, program, create graphics, and continuously improve the EMS in-house is important to most owners. Costs for training, spare parts and EMS software licenses are minimized by using one EMS. This methodology works well. There are no surprises and in the end, it all works, which is the important thing.