Vertical gardens: Nature and architecture in harmony

In recent years, green walls have become a new trend in densely built areas. The inclusion of living nature in big cities not only looks inviting, but also has a number of other benefits and functions.

One glance at the design trends of recent years reveals just how much we long to see more green in our surroundings. From furnishings in natural shapes and colours to plants that transform our homes into urban jungles through to biophilic design – our craving for nature is undiminished.

We’re also feeling a strong urge to see more greenery outside our own four walls. Allotments are more popular than they’ve been for many years, with the pandemic only fuelling demand. However, this demand cannot be met. While there were still over one million allotments in Germany in 2005, there are now only just under 890,000. The reason for this is the great need for building land. In the last 30 years in particular, our cities have grown enormously. More and more often, spacious green areas have to make way for jungles of asphalt and concrete. But it’s not only our personal need to be close to nature that’s driving the call for more plants; climate change also demands a rethink, especially in large cities, and requires the introduction of more green space. So, how can nature be brought back into our urban areas?

Options to help counteract the loss of green spaces include adding plants at ground level, on roofs or on building facades. In places where there’s a shortage of available ground for planting, or where green roofs aren’t possible, vertical facade greening is the ideal way to create an urban ecosystem. Botanist Patrick Blanc is regarded as the inventor of vertical gardens. Today, he uses his “Murs Végétaux” (living walls) to decorate buildings all over the world – from museums and department stores to skyscrapers. The Parisian’s idea is so ingenious that it has opened up a completely new market that’s constantly growing and developing. Meanwhile, all kinds of different ways to create vertical gardens have emerged.

One of the most popular forms is to add greenery using plants that take root in the ground and climb up over the facade. Living walls like these can also be added to existing properties. Other types of vertical gardening involve growing plants directly on the facade. This requires attaching a fleece cover or steel mesh to the house wall and installing a supplementary irrigation system. It’s important to consider the planting method while the building is still in the planning stage.

Many architects still do not incorporate vertical gardens into their plans. Besides the additional costs of engaging landscape designers, this is mainly due to the extra work involved. When a vertical garden is factored into a building project from the outset, the building envelope and building fabric have to fulfil special requirements, which make the design process much more complex. However, projects such as Milan’s Bosco Verticale tower block and the Tree House in Singapore make it clear that the effort is worthwhile:

• Retention and use of rainwater

Because of the many impervious surfaces in our built environment, straightened rivers and heavy rainfall, the risk of flooding is significantly higher than it was just a few years ago. Additional green spaces could store the water and release it again via the plants. Excess rainwater can be collected in tanks and used to irrigate vertical gardens.

• Cooling and insulation

In a direct comparison between a planted exterior wall and a stone facade, a study by the University of Plymouth found that plants make ideal insulation. The planted wall allowed almost 34 per cent less heat to escape through the facade to the outside and also ensured that the temperature inside was much less sensitive to fluctuations in the outside temperature. Natural insulation can significantly reduce heating costs and the greenhouse gas emissions associated with heating buildings.

• Oxygen supplier and pollutant filter

Plants absorb carbon dioxide and convert it into oxygen. They also filter toxins from the air and trap particulates, thereby improving the air quality, especially in large cities with high traffic volumes.

• Preserving biodiversity

Urban areas offer little in the way of shelter for animals, and natural habitat is being increasingly squeezed out. Green facades would be one way of giving lush, species-rich vegetation more space.

• Boosting well-being

Vertical gardens aren’t just decorative, they can also improve our quality of life. That’s because plants can reduce stress, have a calming effect and are even said to strengthen the immune system.

As the population grows, an urban ecosystem is a natural solution to counteract climate change, air pollution and the loss of biodiversity. Vertical gardens can improve air quality in cities, reduce noise and benefit the health and well-being of residents. As an added bonus, living walls can also deliver significant energy savings. Living wall systems are still in their infancy and often come at a high price. However, research has already shown that vertical gardens will be of mutual benefit to architecture and nature in the future.

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