Life cycle based assessment methodologies such as the (environmental) life cycle assessment (LCA), life cycle costing (LCC) and social life cycle assessment (sLCA) are valuable tools for decision support that analyse the impacts of whole product life cycles on individual aspects of sustainability. However, the more aspects are analysed the more difficult it becomes to derive coherent conclusions and concrete recommendations. Integrated life cycle sustainability assessment (ILCSA) builds on these methodologies and provides a practical approach to integrate them. It harmonises the parallel assessment of individual sustainability aspects by introducing common definitions, settings and system models. It is flexible and open to the assessment of any aspect that is relevant to sustainability by any suitable methodology including but not limited to LCA, LCC and sLCA. Furthermore, ILCSA analyses potential barriers that could lead to unintended side effects when attempting to implement scenarios that have been found to be sustainable in the first place (example: limited biomass availability may push operators of an otherwise sustainable conversion plant to using unsustainable sources). Finally, the results are integrated in a structured discussion that does not require debatable weighting factors. This way, synergies and conflicts regarding several sustainability goals are highlighted and can be managed instead of hiding the existent complexity of the systems under investigation.