Check out here http://www.ecobob.co.nz/ for some New Zealand Eco home ideas.
Web based tools for energy design - http://www.wbdg.org/tools/tools.php
BRANZ annual loss factor tool may help you ? downnload the "AFL" tool http://www.branz.co.nz/cms_display.php?sn=17&st=1&pg=1431
And these links are more likely what your after if SU compatablity is required.
Energy Rating software
IES Intergrated Environmental Software
http://www.iesve.com/content/
http://www.iesve.com/content/default.asp?page=s156 (SU Plugin)
YOU can thank me later
Cheers jeff