Green wall of Singapore School of the Arts. Credit Darren Soh

+ Planning departments should make developers think harder about incorporating greening, so that green initiatives, like green walls, may be enjoyed by all on a street – boosting health, wellbeing and productivity.

Private developers are being pushed to incorporate urban greening into their projects, but too often this results in green roofs that most of us will never see. I’d love to see a stronger emphasis on green initiatives that a city’s occupants can enjoy: street planting, window planting and green walls. 

The drivers for urban greening are well understood. As well as benefits for biodiversity, storm water attenuation, air cleansing and urban heat island mitigation, there’s a strong human element. There’s a large body of evidence to suggest that a connection to nature has a positive benefit on wellbeing – increasing happiness, boosting productivity and even making us more resilient to physical illness. 

Cities are well attuned to these drivers and implement a range of grants, mandates and incentives for greening, but generally the focus is on biodiversity or storm water attenuation. Berlin has mandatory requirements for the ratio of ‘ecologically effective surface’ to total envelope area on new buildings. Chicago allows development at higher densities if 50% or more of a roof surface area is covered by vegetation. And Cologne, along with many other cities, offers reductions in storm water drainage connection charges for buildings with green roofs. 

While this is all hugely positive, I call for planners to push harder for pervasive greening that inhabitants can see and appreciate. There’s a huge social benefit to greening that isn’t captured through engineering and environmental criteria. Maybe it could be a remedy to some of our economic woes. Some cities certainly think so. 

The mayor of Paris seems to understand this argument, as does the government of Singapore. Paris has few parks and performs poorly in the World Health Organization’s Urban Green Space Index, so has released large amounts of funding for green initiatives. Likewise Singapore, the ‘Garden City’, first placed an emphasis on urban greening during industrialisation to project a message of stability for investment. Now the state’s aims have migrated towards promoting a knowledge economy – making the city a place in which smart people want to live. Unsurprisingly, both cities lead the way in green wall uptake – the wall at the Musee de Quai Branly in Paris was opened in 2008 and Singapore is planning a 300m green tower by the architect Jean Nouvel.

Of course there are barriers, particularly with green walls. They can be expensive, require careful maintenance, and the reputational risks of a green wall turning brown are considerable. It’s no surprise that developers often hide their greening up on a roof. 

At Arup, our Ventures team are developing a new green wall concept. It aims to be simple enough for a standard façade contractor to install as well as being low maintenance and having a low environmental impact. Crucially, it involves growing plants from seed in-situ so there’s no need to grow plants in greenhouses off site. 

I hope that this will make green walls more accessible, and more common, and that cities and their planning departments will make developers think harder about incorporating greening that you and I can enjoy as we wander their streets.