Among the key barriers to profit in Energy Performance Contracting (EPC) are uncertainties about attaining the realized energy cost savings and potential disputes over the guaranteed cost savings. In this paper, a methodology has been proposed to assist the Energy Service Company (ESCO): (1) to evaluate the risk threshold if the guarantee has already been made, and (2) to determine the guarantee design, if the guarantee has not been made yet, that not only promises the ESCO's profitability from EPC but also maintains its competitiveness to win the bid. Uncertainties within the energy cost savings are modeled stochastically using Monte-Carlo simulation, taking both the energy price fluctuation and the facility performance variability into account. Based on that, a strategic energy savings guarantee design curve is derived, that all the points on it would return as appropriate guarantees. Finally, a campus case is presented to demonstrate the applicability for finding the appropriate guaranteed savings value. This method is also worth popularizing in similar performance-based projects. (C) 2014 Elsevier Ltd. All rights reserved.