The smart grid enabled city is an emerging complex system of systems where different stakeholders will have to strive towards achieving their goals while interacting with each-other. At parts of the city such as the districts, the energy signature and efforts towards its better energy efficiency will heavily depend on the utilization of availability and optimal usage of the local resources. The latter may be very dynamic and depend on several complex conditions such as weather, prosumer behavioural patterns, business interactions etc. An emergent city-wide behaviour appears when a number of simple entities i.e. the prosumers, operate in an environment, forming more complex behaviours as a collective. In order to empower the smart grid city, several energy services capturing the common needs of all stakeholders need to be made available to them. As a result of a (potentially) common platform that offers basic energy services, rapid development of applications can be realized without the need to start from scratch. Such energy services have been identified, analysed and implemented, in the context of a wider enterprise system architecture. An insight on their functionality, usage and development challenges and experiences is provided.