The subject hereof are two typical examples of waste heat and low-temperature heat use and the objective is to evaluate economic effectiveness taking into account various boundary conditions. The first facility considered is an "earth-coupled" heat pump with direct evaporation used as a component of a heating system. The second is an industrial installation, based on a specific project to use waste heat from the cooling process. Alternatively, four different technical options have been considered, including the use of the compression heat pump, absorption heat pump, heat transformer (absorption) and combined system with a gas motor for driving the heat pump compressor. An original simple methodology for economic analysis evaluating uses of low-temperature heat sources as elements of energy supply systems has been developed using input data taken from actual research or industrial projects. The paper also offers a comparison between such energy supply systems operating under different economic conditions of Germany and Poland. (c) 2006 Elsevier Ltd. All rights reserved.