Over time, we have learned how building so much “gray” infrastructure (roads, buildings, parking lots) affects our water quality. To offset these impacts, we’ve started using green stormwater infrastructure (GSI) to bring back trees, plants, and more naturally-functioning stormwater treatment methods. You may be familiar with green roofs, which absorb rainwater and keep buildings cooler. Along those same lines are living walls.
While the ancient hanging gardens of Babylon might be considered a “living wall,” the incorporation of vegetated walls into urban systems as part of a larger green infrastructure effort gained momentum over the last 20 years in Europe. The Vietnamese government has also embraced green walls and roofs as a method for offsetting and adjusting to climate change, piloting several projects around the country. As part of this effort, they created a comprehensive guide to installation and maintenance, including example sites and methods.
Green walls and green roofs:
URBAN ECOSYSTEM-BASED ADAPTATION
to Climate Change in Viet Nam
A living wall works like a vertical version of a green roof. The idea is that these vegetated structures visually soften both interior and exterior walls, provide oxygen, and cool the surrounding area through transpiration. They may entail direct contact of plant material, like vines, with the wall, or more engineered support systems that can handle the weight of plants, potting soil, and water.
As with most emerging technologies, there are pros and cons to using them. Benefits include noise reduction and air quality improvement for indoor walls, while outdoor living walls can absorb stormwater and carbon while providing habitat for birds and insects in an urban environment. Several instances of temporary green walls have been used as aesthetic screens to hide messy construction sites. Living walls are a nice option for smaller spaces, such as apartments and highly urban neighborhoods lacking tree cover.
Complications with green walls include winter dieback and higher maintenance issues, including hydroponic watering systems and trimming or and replacing plants. Over the years, there have been concerns that green walls provide fewer ecosystem services and simply give the appearance of being “green.” Research seems to contradict this concern of greenwashing, however; multiple scientific investigations have indicated reduced ambient temperatures adjacent to green walls and significant reductions in energy use for air conditioning in buildings with green walls.
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