Designing a biomass combined heat and power (CHP) system that fulfils uncertain energy demands is a challenging task. This task becomes increasingly complex when historical data and probability distributions are not well defined. This work presents a newly developed decision analysis design framework for biomass CHP system which considers three types of decision-makers, namely optimistic, pessimistic and cautious decision-makers. To illustrate the proposed framework, a palm-based biomass CHP case study is solved. In addition, sensitivity analysis is performed to evaluate the effect of Feed-in Tariff (FiT) rates towards the design of CHP system. The optimum biomass CHP design is then further analysed to determine the "must-have", "optional" and "must-avoid" equipment within a given range of power demand. The proposed decision analysis design framework enables decision makers to make informed decisions. (C) 2018 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.