A growing trend for green walls is emerging, boosting biodiversity in our towns and cities. According to a recent report by the UK Green Building Council (UK-GBC) externallink, Biodiversity and the Built Environment, the development and refurbishment of buildings can actually improve the ecological value of a site, if done well, and the use of living walls and green roofs can be a key feature.

This point is reinforced by Paul King, Chief Executive of the UK-GBC. "All too often our mindset is simply to reduce the negative impacts from construction and development. But it's important to think about how we can actually increase positive impacts - for people, wildlife and the economy."

He said: "Development done well can and should actually create habitats in which wild species thrive, and a habitat for the human species that we can all enjoy. Green roofs, living walls, and good old-fashioned parks and green spaces in our built environment can make us all feel happier and healthier, and give something back to nature. There is also evidence emerging of the economic value of biodiversity enhancement, which will be a critical driver for the industry."

Living walls, or vertical gardens, are part of a building or structure, utilising the vertical surfaces that would normally be ecologically barren. 

Praised in the report is the 170m long living wall, covered with ferns and flowers, which separates the pedestrian approach from surrounding residential areas at London's giant Westfield shopping centre.

Westfield's owners claim the wall has cut down noise pollution, and has also created an attractive environment which has contributed to all the restaurant units in the centre being let.

Living walls, or vertical gardens, are part of a building or structure, utilizing the vertical surfaces that would normally be ecologically barren. They consist of a variety of plants and some sort of growing medium, supported by a structure. In some cases, where water is plentiful, soil may not be required, which can drastically reduce the weight. As living walls can weigh 30kg or less per square metre, almost any type of wall can be used.

This drive to utilize the built environment to add to biodiversity and improve the urban environment for those living and working there is a worldwide phenomenon. In Mumbai, India, work is underway on a 170m high building, Residence Antilia, which will be the largest and tallest living wall in the world — a vertical garden that will encompass all walls of the building.

One of the tallest buildings in Mumbai when complete, the Perkins + Will designed tower consists of stacked tiers supported by structural pillars, and will not only feature green walls, but will also incorporate several floors of gardens in the residential section, taking up almost half the height of the building.

In the corporate sector, the PNC Financial Services Group, Inc. recently announced plans to create an environmentally friendly living wall at its Pittsburgh, USA, headquarters. The 220m² soil-based living wall on the south-facing exterior of One PNC Plaza will be the largest in North America. Using a variety of specially-selected plants local to the region, the wall will grow into living art.

According to PNC Director of Corporate Real Estate Gary Saulson, "City sidewalks are cooler and quieter thanks to shade and sound absorption by green walls and urban planting."

Using 602 panels of soil-based growth medium, the wall will weigh approximately 22 tonnes when fully watered via an internally controlled irrigation system, and will require just 15 minutes of watering once a week. The wall's designers, Green Living™ Technologies, claim that a south facing living wall constructed using their methods can be 20 to 25 degrees celcius cooler than other surfaces on the same building.

With clear benefits to a building's occupiers and its environment, green walls will soon be a recognized feature of the urban landscape.

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Living facade in Copenhagen at European Environment Agency Headquarters