Because of usage of finite and limited sources unconsciously, especially after industrial revolution and increase in industrial and chemical facilities, there are environmental issues such as global warming, water pollution and ozone depletion. When the construction sector and its environmental impact are concerned, first of all, the building itself creates a negative effect by vanishing the vegetation and flora where it settles. Building destroys as much the soil and the ecosystem as the area of the settlement. Nevertheless, during the construction period, environmental impacts continue as the energy used and the process during production of construction materials. During the production processes of construction materials, there are emissions to air, to soil and to water. For designers and architects, and actors in construction sector, selection of construction materials is an important issue. Recently many construction materials manufacturers have been announcing their Environmental Product Declaration (EPD) in which the environmental impacts are measured. Construction materials that have an EPD can be compared to each other in seven categories in terms of environmental performance. However, these seven categories measured by different units; for instance, Global Warming Potential (GWP) measured in [kgCO2-Eq], while ODP (Depletion potential of the stratospheric ozone layer) in [kg CFC11-Eq.]. Since comparing construction materials with seven indicators is difficult, some institutions developed databases for researchers to unify the results by determining the shadow cost for each category.