Sustainability is a crucial topic in the day to day life as well as in industries. With the help of innovation and new technologies, the negative impacts on sustainability can be decreased. During the development of technologies, the concept of sustainability should be included at all times. This can be done with the help of sustainability assessment methods. However, companies (like the case company of this study) often only adopt one or a few sustainability assessment methods in their product development process. These methods might not necessarily be suitable for the technology under investigation. Furthermore, guidance on when to use which method can be identified as missing within the literature and in practice.

This thesis study aims to fill this gap by developing decision support for the selection of a sustainability assessment method during technology development. Coming from a comprehensive set of sustainability aspects (social, environmental and economic), during the thesis the focus was put on the environmental aspect exclusively. A literature study is used to identify a set of the possible sustainability assessment method. The identified methods are compared to a set of selection criteria based on the method's acceptance, type of assessment, and sustainability pillar covered. Four methods/method groups are identified as suitable for the defined criteria and the study scope. The selected methods are analyzed in more detail to gain a deeper understanding. Based on the knowledge acquired, a flow chart is developed to support selecting the most suitable sustainability assessment method. In order to be able to compare the selected assessment method with other available method, a ranking is developed. The ranking is based on a qualitative comparison and data obtained from the literature. The ranking is displayed in two ways, by a set of spiderweb diagrams and a ranking with numbers. A partial validation of the developed ranking is done by applying two methods to a use case and comparing the practical results with the theoretical ones. Here a mismatch between the ranking obtained from the theoretical data and the one from practical experience can be identified.

The result of the study is the development of decision support consisting of a flowchart and method ranking. Once both steps are followed, it should be possible to provide a fast and easy method selection for non-experts. Furthermore, the common practice of using only one sustainability assessment method (Life Cycle Assessment) is looked into. It can be seen that no sustainability assessment method is best in all criteria and application cases. Therefore, it is impossible to define one most suitable method in all cases. Choosing the right method depends on the scope (substance, product, or material) and the intended outcome. Thus, relying solely or predominantly on Life Cycle Assessment cannot be recommended. Alternative methods should be adopted and applied, also within the case company.