Abstract Many wind turbine manufacturers offer services for their products. The integration of products and services, so called Product-Service Systems (PSS), are intended to support customers over the life time of a product and to ensure a long and successful customer relationship. Besides of the requirements of customers, wind turbine manufacturers have to consider requirements of the government and society as well. Sustainability in all three dimensions, economy, environment, and society, is increasingly relevant in engineering. PSS providers have the possibility to improve sustainability of their products and services over the entire life time and supply chain. For this purpose, novel methods need to be provided to support PSS providers to evaluate and improve PSS sustainability. In this paper, an approach to analyse and reduce the Cumulative Energy Demand (CED) of PSS is presented to improve economic and environmental sustainability. The approach is explained on a wind turbine including training as service. In the approach three subgoals are addressed: First, CED of PSS is investigated. Second, the impacts of changes in the CED of PSS will be analysed, potential levers will be identified and measures derived. Third, strategies based on the measures will be generated which enable a reduction of the CED of PSS.