About 40-50% of global raw materials are currently used in the building industry in the assembly/construction phase and in the use phase of the building and are responsible for 40-45% of total worldwide anthropogenic carbon dioxide emissions (Huovila [5]). These problems have led to the development of legislative policies, regulations and targets to limit material and energy use in buildings. In order to achieve Energy Performance Building Directive's 2020 target towards energy neutral buildings, most regulations and policies focus on decreasing the operating energy, as a result of which this energy has reduced and is still reducing, thereby increasing the importance of embodied energy consumption in buildings. Most of the embodied energy and some of the operating energy of a building is related to the structure. Hence, one possibility is to minimize the energy consumption of a building by varying its structural design. Another possibility is to increase its service life. However, the relationship between adaptability and energy consumption is not always linear. Hence there exists the potential to apply computational methods to obtain a more optimal design from the point of view of energy efficiency and sustainable building design. This paper investigates the development and application of a computational tool that optimizes the conceptual stage design of a building to have minimum embodied energy and some aspects of operating energy, depending on the adaptability required. For this purpose, a parametric computational framework for sustainable building design was developed and implemented by the tool. The working prototype of the tool focuses on low-rise rectangular grid office buildings in steel and multi-objective optimization techniques. Test cases were applied and their results were validated. Finally, conclusions were drawn on both the framework and the tool, and its limitations and possible future developments are discussed.