Microservice is a way of splitting the logic of an application into small blocks that can be run on different computing units and used by other applications. It has been successful for cloud applications and is now increasingly used for edge applications. This new architecture brings many benefits but it makes deciding where a given service request should be executed (i.e. its placement) more complex as every small block needed for the request has to be placed. In this paper, we investigate decentralized request placement (DRP) for services using the microservice architecture. We consider the DRP problem as an instance of a traveling purchaser problem and propose an integer linear programming formulation. This formulation aims at minimizing energy consumption while respecting latency requirements. We consider two different energy consumption metrics, namely overall or marginal energy, to study how optimizing towards these impacts the request placement decision. Our simulations show that the request placement decision can indeed be influenced by the energy metric chosen, leading to different energy reduction strategies.