This research paper deals with a detailed design and optimization of a combined cooling, heating and power plant. This is a detailed fundamental approach to other optimizations and performance evaluation such as optimizing the operational strategy. Different scenarios are introduced and optimized. In addition, influences of prime mover size (e.g. produced power), interest rate and fuel cost on the plant optimum design are studied. Internal rate of return and net present value of the plant are calculated and used to compare the scenarios besides exergy efficiency and carbon dioxide emission. Results show that economic factors affect the optimum cycle thermodynamics greatly. Efficiencies, heat and cooling capacities and fuel flow rates at optimum design point vary significantly by economic factors and are correlated to the plant size.