This paper describes a novel IS architecture for an Energy Management System (EMS) that administers service leasing in a closed marketplace. The field study seeks to discover generally applicable requirements and constraints for domain specific E-Commerce architectures such as the EMS. The finished system will manage a distributed electric power market in a commercial hi-tech business park. EMS facilitates market interaction indicative of principal-actor relationships and auction models. The EMS E-Commerce model differs from typical outsourcing or Application Service Provider models. EMS relies heavily on Component Based Software Development that allows developers to configure the architecture in response to changing market participant roles. A system architect constructs the EMS from software components encapsulating mission critical electric power and IS services. Those service components are leased over the Internet in order to meet changing circumstances in the market and domain. JiniTM provides the computational infrastructure used by the EMS to establish and execute service leases on components. Preliminary results indicate the JiniTM architecture is an appropriate technology to develop the EMS and marketplace.