Distributed energy systems (DESs) are becoming increasingly popular because of their high-energy efficiency and low pollution emissions. Accurate performance evaluation of such systems is critical for processes at the early design stages. However, there are considerable uncertainties in terms of the parameters used for performance evaluation and design optimization, including component efficiencies, customer demands, and energy markets. These uncertainties can significantly influence the performance of DESs. Without consideration of these uncertainties, the performance of DESs can be overestimated or underestimated, which leads to inaccurate decision-making. Therefore, this paper presents a comprehensive evaluation of the performance of DESs by considering uncertainties in 12 parameters that relate to the electrical and thermal efficiencies of generators, efficiency of chillers and pumps, load density, energy markets, and so on. The energy and economic performance of DESs under each uncertainty are analyzed and compared with that of conventional energy systems. The suitable conditions for using DESs and other factors that can influence their performance are determined. The results of this study can serve as a guide for design optimization and policy development to promote the use of DESs in China. (C) 2019 Elsevier Ltd. All rights reserved.