was ready by 1997, and a polished version was introduced to the commercial market in 1999. It helped to establish Dutch building assessment in rigorous LCA, but quite differently than the ATHENA system, geared more for a market-driven context. Beside the national systems geared to specific markets, the Green Building Challenge (GBC) has emerged internationally as a means for researchers and practitioners in building assessment to test systems and strategies. A consortium of over 30 countries, the GBC process was launched by Natural Resources Canada in 1996, but in the early years included mainly European members. Its main goal has been to advance the stateof-the-art in building environmental performance assessment methodologies, and to do this through periodic conferences, and the formulation of an internationally accepted generic framework. The framework would be used to compare existing building environmental assessment methods and to produce regionally based industry systems. The GBC has also served to showcase the performance assessments of environmentally progressive buildings. It has held conferences in 1998 (Vancouver), 2000 (Maastricht, the Netherlands) and 2002 (Oslo Norway). It has been growing rapidly, but its role has changed as more national systems have emerged. Its calculation toolthe GBTool while not geared to a specific market is making contributions to the field of building assessment that can be used by future versions of national systems (J. A. Todd, Crawley, Geissler, & Lindsey, 2001). In North America, the most significant development has been the emergence of the Leadership in Energy and Environmental Design (LEED) system. LEED is a selfassessment and the rating system developed by the US Green Building Council (USGBC). The Council was founded in 1993, but has in recent years exploded in