These are apparently taking off. Walking down Piccadilly, I was surprised and uplifted to see a building with walls made of garden. It was like a huge curtain of moss and plants, so soothing and pleasant to see in a tough grey city. From this article by Joe Swift of The Times:
As well as being a fabulous aesthetic solution, green walls also tick many environmental boxes, too. Plants significantly improve the surrounding air quality, reduce sound pollution, increase biodiversity, insulate buildings and, most importantly, cool our increasingly sweltering cities in the summer. The “urban heat island” effect means that our predominantly concrete, glass and tarmac cities hold on to heat and can be up to 6C hotter than the surrounding countryside. Sure, we’ll need thousands of square metres of green walls to have any reductive effect, but at least we now have the tools.
The Independent's Emma Townshend also has information about the creator, designer and gardener Patrick Blanc.
I think it's a fantastic idea. With the right plant choices, this could go well in subtropical cities like Brisbane: imagine if we could reduce residual heat, glare and improve both air quality and quality of life, just by rethinking urban design? I want a green wall totally made up of Venus flytraps, near a public barbecue area. Down with summer flies!