According to C40 Cities, more than 970 cities worldwide are expected to experience average summertime temperature highs of 35˚C (95°F) this year. This trend, exacerbated by climate change, will negatively affect all aspects of day-to-day life including working, socializing, and traveling. Well aware of that, cities are now exploring ways to provide some respite to their residents, by greening up their built environment.
Cities are particularly vulnerable to climate change-induced rising temperatures because of the ‘heat island’ effect, which occurs when buildings absorb and trap heating from the sun during the day and release it into the city during the night. These heat islands render urban areas increasingly unbearable and can artificially increase temperatures by 10-15˚C above a building.
Fortunately, integrating nature within the facades of buildings in cities offers a great opportunity to effectively combat the heat island effect whiles jazzing up the aesthetics of the cityscape.
In addition to lowering cooling costs by shading buildings, green facades (or green envelopes) can also reduce noise pollution by absorbing sound, as well as clean the air of fine dust and particulates. What’s more, expanding green envelopes within a city is a particularly attractive solution given the limited space for green areas in cities, such as parks, gardens, and trees.
By growing plants on just 20 percent of the surface areas of only 20 percent of the buildings in an entire city, residents of urban areas can benefit greatly. This is called the 20-20 approach, explains Rudi Scheuermann from British engineering firm Arup, which modeled the benefits of this solution:
“In London, we calculated that green envelopes would lower the air temperature by three degrees, a significant difference,” says Scheuermann. “We also found a 4-degree reduction in Berlin, 10 degrees in Melbourne, and a huge 11-degree drop in the incredibly dense environment of Hong Kong.”
As cities are poised to only get hotter with climate change, expanding nature-based solutions like green facades will play a key role in minimizing the risks of climatic events, while also making our urban areas cleaner and more enjoyable.