This work presents an optimisation based approach for the integrated plan and evaluation of Distributed Energy Resources (DER) systems. The mathematical model takes into account site energy loads, local climate data, utility tariff structure, characteristics of the candidate DER technologies (technical and financial) as well as geographical aspects. The optimal integrated DER system is selected by minimising the total energy cost while guaranteeing reliable system operation. As an illustrative example, we consider a neighbourhood in Athens (Greece), where several options for satisfying its electricity and heat demands are investigated. The adoption of DER technologies combined with a heating pipeline network and a microgrid is examined. (C) 2012 Elsevier Ltd. All rights reserved.