Jan. 10, 2018

Central London hotel Athenaeum has seven stories of lush greenery winding up a corner, while the entire side of Madrid museum and cultural center, the CaixaForum, is blanketed in plants and flowers.

In Paris, the entrance to the Musée du quai Branly is a green wall of 15,000 plants across 800 square meters – and by 2020, the city aims to have 100 hectares of plant-entwined rooftops and walls, reports real estate website JLL.

“Green spaces do more than make the urban environment look more attractive,” says Ashley Perry, senior project manager at JLL. “They often have a positive effect on the well-being of city dwellers, helping to reduce stress and improve mood.”

The natural world also benefits as greenery on rooftops and walls can encourage biodiversity by attracting local birds and insects, defuse heat from dense urban structures and help mitigate climate change. In addition, the profusion of plants along green walls can also improve urban air quality by trapping polluting particulates and removing carbon dioxide from the air, replacing it with oxygen.

A smart green choice

For building managers, green walls can represent efficient design – plant-covered walls help mitigate wind impact and insulate interiors. However, not all green walls are created – or maintained – equally.

Deciduous species, which shed their leaves in winter, are better at improving heat efficiency – in spring and summer, leafy boughs contribute to shading from the sun, while in winter, bare branches maximize the impact of weaker sunlight. As a result, Perry notes, green walls are likely best suited to temperate climates with reasonable levels of both sunlight and rain.

Some modern buildings are already taking the concept beyond single walls. In Milan, architect Stefano Boeri is pioneering the concept of vertical forests that wrap around residential highrises.

And the idea is catching on. Paris is planning its first vertical forest tower, while Boeri’s firm also has similar projects in the pipeline for Switzerland and the Netherlands, and an even more majestic version, the Liuzhou Forest City in China, which will be a 342-acre neighborhood covered in 40,000 trees and nearly a million plants.

Living walls can work equally well indoors. The Mandarin Oriental Hyde Park features a wall of landscaped foliage in its internal courtyard, while London’s Heathrow Airport trialed a “Garden Gate” with nearly 1,700 plants to create a sense of calm for departing passengers.

More than looking green

As green walls and vertical forests become a benchmark in modern sustainable design, there is a need to determine how they can improve a particular building’s immediate environment and quality of life for residents and pedestrians.

“Often green walls are seen to soften projects, such as industrial or retail schemes, but there is a danger of this appearing to be ‘green-washing’ rather than providing a tangible positive impact,” Perry said. “Green spaces are shown to maximize visual impact and well-being – but why not improve the landscape at ground level as well?”