Although the importance of reusing products has been stated frequently, both in legislation and by academics, the scientific literature does not provide comprehensive and systematic methods of assessing the reuse of a generic product from an environmental point of view. Moreover, the definitions of reuse provided in the literature and legislation are not always consistent. This article introduces an original classification of different types of reuse, including some suggested definitions. It then focuses on remanufacturing, a type of reuse in which a used product (or its components) is returned to at least its original performance level. The article describes the development of a method for assessing, from a life-cycle perspective, the potential environmental benefits of remanufacturing energy-related products. The method includes several novel aspects: it helps to analyse possible trade-offs between potential environmental impacts and energy efficiency; it allows the independent modelling of some parameters that influence product reuse; and it can be applied even at the early stages of the design process, when some specifications may not yet have been defined. The environmental impacts of a product's life-cycle stages are used as input parameters for the assessment. The method is then applied to an enterprise server, a case-study product for which remanufacturing is a current market practice. A sensitivity analysis is included to check how uncertainties could affect the overall results. The results of the case study show that remanufactured servers, even those that are less energy efficient, can have lower environmental impacts than new ones. For example, reusing some components (e.g. hard disk drives and memory cards) is environmentally beneficial even if the remanufactured server consumes up to 7% more energy than a newly manufactured server. The case study also demonstrates how the method proposed could be used in the context of product policy discussions.