High-density cities are waking up to the benefits of verdant walls, as the lack of green spaces on the ground are leading to vertical urban gardens running up and down building façades. Let’s not forget that sustainability is as much about humanity as it is about greenery – about providing spaces that improve quality of life. So why not have the sustainable cities of tomorrow, here, today? We certainly have the technology and expertise in place. Verdant walls are sprouting in many Asian cities, the vertical equivalent of horizontal green roofs. As many Asian cities are ultra-dense, vertical cities with little room for surrounding greenery, dominated by concrete, steel and glass towers, this often leads to a craving for more visible vegetation, which may be resolved by façade planting that doesn’t take up any precious land. Imagine gardens reaching 80 stories high on the outer walls of a skyscraper, providing environmental benefits like filtering out air pollutants and helping to cool down cities.
Designed as a top-tier business hotel and office in a garden, Parkroyal on Pickering with a gross floor area of 7,500 square meters aims to show that not only may greenery be conserved in a built-up high-rise city center, but that it has a strong role to play in reinforcing Singapore’s unique image as the garden city and serving as an example for other urban environments. Completed in January 2013, Parkroyal is located in central Singapore, between the CBD and the districts of Chinatown and Clarke Quay, facing Hong Lim Park. Greenery from the park is echoed in the building in the form of planted valleys, gullies and waterfalls. The landscaping also conceals openings to the aboveground carpark, while cooling and naturally ventilating the space.
At the top of the sculptural podium, imitating landscape formations – rocky headlands, promontories and green planted terraces, resides a lush landscaped terrace housing the development’s recreational facilities with infinity-edge pools and unobstructed city views. Immense sky gardens, inserted into courtyards every three floors up, bring vegetation directly to the rooms, provide sun-shaded and well-ventilated relief spaces, and break up the scale of the building. Tall overhangs and leafy foliage protect from the weather and direct sun. Elevated gardens bring nature closer to occupants, which was once the preserve of those living in landed homes, and increase opportunities for interaction and the formation of communities.
A total of 15,000 square meters of sky gardens, reflecting pools, waterfalls, planter terraces and green walls are included, equivalent to more than double the site area. Shade trees, tall palms, flowering plants, leafy shrubs, overhanging creepers and other species distributed throughout the building create a tropical setting for people, insects and birds, extending Hong Lim Park’s greenery and promoting biodiversity. These landscapes are designed to be self-sustaining and rely on minimal resources: rainwater collected from upper floors irrigates planters on lower floors through gravity without running pumps, while rooftop photovoltaic cells power grow lamps and softscape lighting, in the hope of creating the world’s first zero-energy sky gardens.
A representative of WOHA, the architects in charge of Parkroyal, remarks, “This organic approach requires less maintenance compared to a structured or manicured one, as it allows for more natural growth. We’ve also automated the irrigation system to reduce day-to-day attendance, but some periodic maintenance is required. We also designed the planting concept and selected plants that require less maintenance, so yes, we firmly believe that the benefits outweigh the costs, and since the greenery is also the USP of the hotel, all interests are aligned to ensure that it is thriving. Despite the extensive amount of greenery, the cost actually works out to be less than one percent of the construction costs, so it is actually not expensive.”
On the west-facing back façade sandwiched between tall buildings, partially set in from the building edge, vertical planting appears as a textured green wall made of ferns, as they are accustomed to shade, need few nutrients, come in a variety of sizes and shapes and require practically no maintenance except for the occasional replacement of dead plants. A WOHA representative discloses, “Vertical green facades are tricky: suitable plants have to be selected as most are more accustomed to growing horizontally on the ground. The right medium has to be chosen to provide the nutrients and also support for the roots, as the plants will be placed vertically. Some kind of restraint is also required to keep the medium in place so that it doesn’t drop or wash off in the rain. Access for maintenance is also required, which may be difficult if the green façade is very tall.
“We are adapting the idea of our sprawling garden city onto high-rise building typology with the same sense of relief and delight as one would get from a park on the ground. The large amount of greenery and landscaping will contribute to the reduction of the urban heat island effect by absorbing heat, shading hard surfaces and evaporative transpiration. These then lead to lower energy consumption in air-conditioning, etc. Air quality is improved and greenhouse gases lowered by the absorption of carbon dioxide and giving off of oxygen through photosynthesis. We believe that urban greenery does have true environmental benefits. However, they have to be seen in context. The effects of localized greenery will only be felt in their immediate area. There needs to be critical mass, for example, when a whole neighborhood or district implements urban greenery, for there to be a significant impact on an urban scale.”
One can’t deny the negative impact buildings and cities have on the environment, but vertical planting can be a powerful means to diminish or correct this damage. Still in a nascent stage, green façades will take time and effort to be widely accepted, but there’s no denying that they’re gaining momentum in many Asian cities. A WOHA representative concludes, “Yes it’s a growing trend as there are clear esthetic, positive psychological and environmental benefits. We hope that our designs have shown how they can be practical, integrated and also architecturally striking, and that they will encourage others to do the same.”
