This paper offers a conceptual frame work for sustainable space design optimization problems and objectives on which space optimization model is built. The study is based on understanding the philosophy of optimization, its problems and objectives; then classifying them into logical groups  on which optimization model frame work can be created. This frame work links classical design optimization problems to sustainable design goals through space as being the smallest building design component. The research starts with defining general building design optimization problems and sustainable design goals specifically green design practice as being the most propagating sustainable practice approach , then it moves forward to make a projections of these two subjects on space design. This framework  offers a wider vision for the meaning of sustainable space. The most common understanding of sustainable space is related to the enhancement of indoor environmental Quality. This can be recognized though different green rating and assessment methods. Through this model more dimensions can be added to improve the efficiency sustainable space design. The importance of this research work is that it provides the conceptual approach for the optimization model which can be enhanced  mathematically and implemented practically through future research work. It also give awareness for more dimensions that can be taken in consideration at early design stages .This will have a positive impact on space design quality. Also this conceptual frame work  can be a guide line for architects to customize their space design to fit space optimization problems. This will generally enhance sustainable design movement.