This paper presents a general methodology to roughly estimate in advance the actual performance of mu-CHP (micro Combined Heat and Power) systems in one year of operation, by means of limited information on the CHP prime mover efficiency and emission factors in selected set points and by means of a simplified prediction model of the operating cycle. The carried out analysis has been applied to several market-available and under development mu-CHP units of different technologies (Internal Combustion Engines, Micro Gas Turbines, Organic Rankine Cycles, Stirling, Thermo Photo Voltaic, Fuel Cell), operated under a hypothetical virtual operating cycle. The virtual cycle is obtained in this paper on the basis of the year thermal demand of a domestic user, assuming thermal load following of the CHP system. The methodology can be generalized to different applications and different management logics of the CHP system. (C) 2013 Elsevier Ltd. All rights reserved.