Buildings are becoming considerably more energy-efficient and thus achieving greater thermal comfort. This study was conducted to develop an optimization model that simultaneously takes into consideration the occupants' thermal comfort, thermal energy consumption, and life cycle economic-environmental values. To this end, a multidisciplinary approach was adopted involving the analysis of the thermal comfort and thermal energy consumption through the EnergyPlus, and the quantification of the economic-environmental values through a life cycle cost analysis and life cycle assessment analysis. For the validation of the proposed model, a case study was conducted. A library facility in a monsoon climate as the target was chosen for this. A total of 4.26 x 10(12) possible building design scenarios (31 window types x two ventilation types x 8(12) (eight set points: 18-25 degrees C, 1 degrees C intervals per month)) were generated and used to calculate the optimal building design solution. Based on the tables for making a better decision, trade-off analyses among the five optimization objectives were conducted. In terms of efficiency, the results showed that the time required for determining the optimal solution was only 2 s for each scenario, excluding the EnergyPlus running time. The proposed model may therefore be applied to other energy-saving techniques and buildings. (C) 2019 Published by Elsevier Ltd.