Vertical greenery will be the defining feature of future metropolises, according to urban policy experts, as governments across the globe invest millions in making their cities 'smart.

"Vertical green architecture is definitely a need for smart cities," said Matthew Clifford, head of energy and sustainability services, greater China at real estate services firm JLL. "You can have a great interconnected city but if you don't have an energy efficiency strategy in place, is it really a smart city?"

The idea of integrating greenery into a building's façade offers a practical spatial solution to environmental issues like carbon dioxide emissions, a by-product of urbanization. Green walls, roofs and gardens offer protection from ultraviolet rays, reduces ambient temperatures and keeps building interiors cool, which in turn decreases demand for air-conditioning and curtails a building's carbon footprint, explained Ng San Son, associate director at DP Architects.

"While information technology may be the main infrastructure and driver of a 'smart' city, green architecture plays a key role by creating a better quality of life. If people take pleasure in their surroundings, this contributes to higher productivity and a reduction in energy consumption in a smart city," he added.

Major players

Singapore, often referred to as the Garden City, is globally recognized for its investment in the sector as it aims to become the world's first smart nation by 2020. A 24-story residential condominium by City Developments Limited (CDL) set the Guinness World Record last year for the largest vertical garden, while the government offers commercial and residential customers 50 percent subsidies for installing vertical greenery solutions.
Greenery is a mandate in Singapore's new construction projects, explained JLL's Clifford. "It's an energy tool, not just an aesthetic. The city is an importer of energy and realizes it has finite resources so development is heavily skewed towards energy efficiency."

Elsewhere in Asia, Seoul and Bangkok are also spearheading the vertical green movement with projects like the Seoul New City Hall and Siam Paragon buildings.

While the trend is undoubtedly growing, it's more common in developed regions like Europe and North America. The city of Paris recently commissioned architect Vincent Callebaut to help the city achieve its goal of reducing 75 percent of greenhouse gas emissions by 2050. The result was eight high-rise towers featuring green walls that recycle their own energies, solar energy generators that churn out biofuel and wind turbines that produce electricity, according to the project's outline.

Developing nations still aren't prioritizing sustainable design as a long-term solution since governments remain preoccupied with architecture that fulfils basic needs and address socio-economic disparities, DP Architects noted.

From gardens to farms

In addition to green walls, farming is also a key element of vertical design. By growing crops indoors stacked in racks to the ceiling, harvests remain safe from bad weather and infestations, providing an innovative solution to rising food demand in urban populations. The United Nations estimates that urban agricultural solutions like vertical farming is practiced by 800 million people worldwide and constitutes 15 percent of global food resources.
Darren Neo, the director of a Singaporean landscaping firm specializing in vertical gardens, opened an office in China two years ago where he sees massive potential for vertical farming.

"China's food scandals are so high, and vertical farming can be a great solution to that despite a lack of outdoor space" he said. "Installing green walls in your house, say in the living room, means you don't get any pests, resulting in pesticide-free herbs."