In literature, many models (qualitatively as well as quantitatively) can be found to cope with the problem of communicating results of LCA analyses with decision takers. In a previous article of this Journal, an LCA-based single indicator for emissions is proposed: the 'virtual pollution prevention costs '99' (Vogtländer et al. 2000a). In this article, a single LCA-based indicator for sustainability is proposed. It builds on the virtual pollution prevention costs '99 for emissions, and adds the other two main aspects of sustainability: material depletion and energy consumption. This single indicator, the 'virtual eco-costs '99', is the sum of the marginal prevention costs of: - Material depletion, applying 'material depletion costs', to be reduced by recycling - Energy consumption, applying 'eco-costs of energy' being the price of renewable energy - Toxic emissions, applying the 'virtual pollution prevention costs '99' The calculation model includes 'direct' as well as 'indirect' environmental impacts. The main groups of 'indirect' components in the life cycle of products and services are: - Labour (the environmental impacts of office heating, lighting, computers, commuting, etc.) - production assets (equipment, buildings, transport vehicles, etc.) To overcome allocation problems of the indirect components of complex product-service systems, a methodology of economic allocation has been developed, based on the so called Eco-costs/ Value Ratio (EVR) model. This EVR calculation model appears to be a practical and powerful tool to assess the sustainability of a product, a service, or a product-service combination.
