Building Assessment & Certification Systems As noted above, limiting evaluation to individual materials can be a problem since so much depends on how these materials are used and combined together. The emergence of environmental assessment systems for assemblies and for whole buildings is a logical evolution of both green building and industrial ecology. The ATHENA Sustainable Materials Institute has developed a typology of assessment tools that has been well received by professionals in the area (Trusty, Meil, & Norris, 1998). It comprises three kinds of tools. Most in the level 1 categoryproduct assessment toolswere covered in previous sections. Level 2 tools are whole building decision support tools that focus on a specific area of concern. They are software programmes or systems that calculate life-cycle environmental impacts, or operating energy, or life-cycle economic costs, or perhaps some simple combination of these things. They include the ATHENA design tool, the Dutch Eco-Quantum programme, the British ENVEST programme, and the US DOE2 programme. They usually involve some kind of weighting or scoring, and the results can contribute to level 3 tools. Level 3 building assessment tools include the national building assessment systemslike the UKs BREEAM, the USs LEED and Norways ECOPROFILE along with international systems like the GBTool. They synthesize a whole range of issues that constitute an agreed-upon definition of sustainable or green. They combine