I feel slightly unsure about giving a star rating for Technique cause I know very little about HDR beyond a vague comprehension of how its done (without any experience to back it up, in my case) and an appreciation for how cool it looks when done well and with a big dose of colour.
I haven't seen many HDR images of people, so this feels very fresh to me. Many HDR pictures I've seen have a muted colour palette, something to do with the tone mapping or other technical aspects I know nothing about, but this one is vivid and bright, benefiting from a strong acidic palette.
The subject is very appealing, hinting at a bigger picture, a longer story. You've created a deliciously enticing and luminous picture which I stared at for quite a while before collecting my thoughts and starting to type.
I know we haven't known each other for long so I may be premature in saying this, but you seem to have hit on a very striking and memorable personal style with this photo, something I can't quite put into words but would love to see more of.
The green was from the reflection off of the ferns around the building. It was a great place to shoot. The post was simply some "fake" HDR with multiple raw exposures and some light tonal changes in photoshop.