May 5, 2023

Of Course, Nature Can Save Our Hot, Polluted Cities: Meet the CityTree Image: A CityTree in Cork, Ireland | Green City Solutions Green City Solutions has combined air-purifying moss with IoT technology in a smart biotech filter that can clean 82% of fine dust particles from the air, and humidify and cool it by up to 4°C. Global air quality has been declining over the years; and the effects are hardto ignore: According to the World HealthOrganization , 99percent of the population is now breathing in polluted air; and it isresponsible for 7 million premature deaths annually. More than 50 percent of thepopulation lives in cities — which are hotspots for airpollution — a number predicted to reach 68 percent by 2050. Incredibly harmful to humanhealth, air pollution is linked to public health concernsincluding cancer, cardiovascular disease, respiratory diseases, diabetes mellitus; andvarious reproductive, neurological and immune disorders. Urban areas can also become “heat islands” — where temperatures are higher,thanks to the abundance of concrete surfaces absorbing, rather thanreflecting ,the sun's heat. With climate change, heat-island temperatures will be hottereach year; and as more people migrate to cities, the number of people vulnerableto the health effects of air pollution will also increase. German startup Green City Solutions (GCS) is, much like its name suggests, on a mission to clean city air bybringing nature back. Combining pollution-absorbing plants with digitaltechnology, Green City’s solution merges air-purifying moss with smart sensors,active ventilation and irrigation technology. The company spent yearsresearching and developing its solution — with a key breakthrough involving theidentification of the most suitable species of moss (out of 16,000 potentialcandidates), which is now growing at the company’s vertical moss farm. “As the first green plant on our planet, moss can absorb and bind particles fromthe air like no other plant. It stores water and serves as a natural airconditioner through evaporative cooling,” founder and CEO PeterSänger told Sustainable Brands®. “Because it absorbs everything it needs viathe air, it can reduce pollutants like fine dust. Most of the absorbed fine dustis metabolized, which means that the moss grows on the dirt in the air. Theseproperties make moss a perfect ally in the fight against air pollution and heatislands in cities.” Green City’s solution works with the help of vertical moss mats inserted intobiofilters. A ventilation system then draws in polluted and heated city air andpasses it through the dense layer of moss, which leaves the air much cleaner andcooler — the filters humidify the air and cool it by up to 4° Celsius,creating fresh air zones. The system can help drastically improve urban airquality — where the population is dense and where greenery might have a hardtime taking root thanks to all the paved surfaces. The moss-filter technology is integrated into different formats that offermultiple benefits in areas where space may be limited: The CityTree with its seating, forexample, also functions as streetfurniture ; whilethe CityBreeze combinesthe moss filter with a large, digital screen that can serve as a sustainableadvertising or information pillar. They can also work as charging stations fore-bikes or electric vehicles, or provide an open WLAN hotspot. CityBreeze in Leipzig's Allee-Center | Image credit: Green City Solutions With the cleverly integrated IoT technology, GCS can supervise the status andperformance of every filter in the field. The technology ensures the vitality ofthe moss and makes the moss filter a low-maintenance, long-lasting system. Thetechnology also makes it possible to measure the amount of air filtered andcollect relevant data on air quality. “Since air pollution is not always visible to the human eye, we visualizeair-quality-related data and provide them as part of performance reports to ourcustomers,” Sänger explains. “The temperature and air humidity of the inflowingand outflowing air can also be determined. The data can also be shown on screensright on the biofilter itself. This helps a great deal to make an intangibleproblem more relatable for the public.” CityTrees have been successfully planted in cities including Berlin, Leipzig, London and Cork, Ireland. In third-party assessments, GCS was able to demonstrate a fine-dust filtereffect of up to 82 percent for its moss filters, with air improvement stilldetectable at a distance of 5 meters. Sänger says the CityTree can clean the airfor 10,000 people per hour. GCS’ goal is for its products to be part of a multipronged solutionto provide clean and fresh air for 500 million people by 2030 and contribute tothe decarbonization of urban infrastructure. “Our products can be an important element in the transformation of cities to behealthier, more sustainable and climate resilient. Of course, there is no singlecure-all here — ideally, our products are always embedded in an overall strategyconsisting of various measures. For this purpose, we like to work together withdifferent stakeholders during the implementation to achieve an optimal result.”