This paper presents a mixed-integer linear programming (MILP) super-structure model for the optimal design of distributed energy generation systems that satisfy the heating and power demand at the level of a small neighborhood. The objective is the optimal selection of the system components among several candidate technologies (micro combined heat and power units, photovoltaic arrays, boilers, central power grid), including the optimal design of a heating pipeline network, that allows heat exchange among the different nodes. The objective function to be minimised contains the annualised overall investment cost and the annual operating cost of the system. We show that besides the usual energy balance and unit operations constraints, additional equations must be included in the model to guarantee correctness of the produced heating pipeline designs. A special instance of the problem where a single centralised combined heat and power unit is installed in the neighborhood is also considered. The efficiency of the proposed model is evaluated through illustrating examples. (C) 2012 Elsevier Ltd. All rights reserved.