This paper proposes a computer-based method for providing product designers with real-time environmental impact assessment. In this concurrent modeling approach, environmental experts build life cycle models, define their interfaces, and publish them as distributed objects on the internet. Traditional designers integrating these objects into their design model have access to the impact assessment methods provided. Communication between these models is the primary focus of this paper — methods for establishing and maintaining this communication are described in detail. A beverage container design example illustrates how this collaborative approach can be effective in determining tradeoffs between design alternatives.