Thanks for your reply.
I prepare to use Autodesk Building System 2005. I have no idea about this actually.
When I read " New Features Workshop", it says we can export zone data in Green Building Extensible Markup Language(gbXML) format"
" External tools can calculate the heating loads, cooling loads, and air flows for each engineering space. You can import these result into your Building Systems drawing using the Import gbXML feature. Then view the load calculations in the Engineering Properties dialog box."
I have following question: What does external tool mean? Do I need to find a load calculaiton software that can import gbXML? Do you know any calc software support gbXML format? Will import and export gbXML format really make our job easier and more significant?