The use of a solar cooling system has the potential to reduce the amount of energy required for cooling buildings. One of the most important methods of improving energy efficiency in buildings is by carefully designing building fa ades. A facade integrated evacuated tube collector (ETC)-organic Rankine cycle (ORC)-vapour compression cycle (VCC) was applied in this study. To optimise the design parameters of ORC, a steady-state semi-empirical model was developed in Engineering Equation Solver (EES). The optimum number of plates in each heat exchanger is obtained by maximising the net present value (NPV) of electricity savings. The financial performance of the optimised system was assessed through a unit cooling cost (UCC) analysis. It was found that the UCC of the optimised facade integrated ETC-ORC-VCC system is $0.24 per kWh(r) of cooling effect. Crown Copyright (C) 2016 Published by Elsevier Ltd. All rights reserved.