In the goal and scope definition, important decisions about the study are made such as the reason why the LCA should be performed and the questions to be answered, the functional unit of the system studied, the system boundaries, the data quality required and other hypothesis or limitations of the study. In the Life cycle Inventory step, all inputs and outputs (of material, energy, waste, etc.) of the system are compiled to calculate the impacts associated. The inputs and outputs of the system also have inputs and outputs of energy, material, waste, etc. associated which should be taken into account. This is the approach followed in a life cycle perspective. The Life Cycle Impact Assessment enables to value the results obtained in the Life Cycle Inventory and assess the impacts of the product or system. For this step a characterisation method is required. Several impact methods exist, and they each propose certain impact categories(แคท ที โกรี่) and their corresponding characterisation model to calculate the environmental impact or damage results.