Upside aims to build an ICT service that aggregates energy storage capacity in thousands of small devices and coordinates the charge/discharge cycles of these devices to create a coherent energy store that can be used to manage demand on the grid. By working with a wide range of devices (e.g. Uninterruptible Power Supplies, Electric Vehicles, battery storage systems for domestic solar arrays, heat pumps), we can build a significant energy store with very flexible operating characteristics. Our initial target is to build a 30MWh store from "spare" capacity in small (<50kW) UPS currently installed in the UK. Such a store can be made financially viable by offering it to National Grid's Fast Reserve scheme. By shifting demand from peak periods to times of higher renewable generation, such a store can also significantly reduce CO2 emissions associated with electricity generation. An initial prototype for Upside is being developed for the finals of the Nesta Dynamic Demand Challenge. This project will help us build a pilot-scale service with a novel, "pluggable" ICT architecture, develop new algorithms for coordinating additional classes of device, and explore emerging business models.