Wonderful image Peter, and as a NZer maybe I should be able to offer assistance...
Sadly I am from the Deep South (next step Antarctica) so I cannot claim any local knowledge.
Google came up with this article, if the link works for you.
http://www.bvn.com.au/projects/asb/
(Scroll down for more information rather than swipe through images)
The mirrors on the North Facade are a sunscreen and reference the native NZ Pohutukawa tree.
Well seen & photographed as now knowing more about the subject, I’d imagine it would be tricky, you have done it justice here.