Sustainable architectural design process is more complicated than traditional building design because it has its own regulations that require calculations and comparisons that also need to be considered. For this article, sustainability parameters were accepted as the standards of green building certification systems (LEED and BREEAM), local climate conditions, and local building regulations. There are conflicting criteria according to those sustainability parameters. As a result, Pareto genetic algorithm was chosen to address multiple objectives by incorporating the Pareto concept of domination. An efficient, sustainable design should be developed during conceptual stage, when the most important decisions are made, so that a decision support system can be developed with the help of Pareto-based non-dominated genetic algorithm (NSGA-II) to evaluate several possibly conflicting objectives. This article discusses a model that aims to produce site layout alternatives according to sustainability criteria for social housing units.