Urban Eye: Hope-Gibbons carpark
Planter boxes transform a multi-storey carpark on Taranaki St into something almost pleasant: The Carpark Gardens of Babylon
The planter boxes don't strictly count as an extra "use" of the building, so they don't contribute to density or liveliness, but they do provide a visual element that would otherwise be lacking. It would be even better if there was a way to add actual variety and vitality (such as street-level shops as a "skin" to the building), but most elevations are already shielded from the street by other buildings and the amount of blank wall at street level has been minimised quite nicely.
There's not much explanation required here: most people prefer foliage to bare concrete. More of the concrete could have been covered by creepers, or the remaining hard surfaces could have been given a more interesting design, but otherwise this is a huge improvement over the standard façades for multi-storey carparks.
"The vertical belongs to man and the horizontal to nature", according to Hundertwasser, but this shows that even the vertical can be partly returned to nature.
Though carparks by their very nature encourage car use, a multi-storey carpark uses less land than surface parking, and the vegetation at least provides a token palliative against the greenhouse emissions of the cars within. I believe that the top level is still exposed asphalt, rather than permeable paving with soakaways, so there is room for improvement by making the horizontal element more compatible with nature. I don't know whether greywater from the roof is currently being used to water the planter boxes, but that would be an obvious way to reduce both runoff and maintenance.
It could be argued that this provides a more pleasant urban environment for everyone, but there are no specific measures in favour of social justice or community cohesion.