The environmental impact of human activities has been a concern for engineers and architects for centuries, from limitation of energy and raw materials to predicting future energy and resource demands. This review demonstrates how life cycle assessment (LCA) and life cycle costing (LCC) tools can be used to support design decisions in the building industry throughout the design process. The study is primarily based on DGNB certification projects in Denmark conducted by the engineering consultancy company Ramboll and focuses on how LCA and LCC tools can be used in the early design stages to quantify decision making and how tools are used in the final stages of a certification process to verify the building geometry with regard to life cycle costs and environmental impacts.