Long Xie envisages a future cityscape with vegetated facades

In the Nessling Foundation’s autumn 2021 general call for grant applications, a total of 24 grants were awarded.

Long Xie studies how urban stormwaters could be harnessed with the help of vegetated roofs and facades. These ecosystem services can also provide on-site stormwater management.

Also read the interviews of Anni Orola and RARE Media.

Long Xie. Picture: Eeva Murtolahti

Long Xie. Picture: Eeva Murtolahti

What are you researching and why?

“My name is Long Xie. I graduated with a Ph.D. in Science (Agriculture and Forestry) from the University of Helsinki in 2020. During my master studies, I participated in a vegetated roof research group in which I have learned and developed an interest in knowledge about vegetated roofs and facades. During my doctoral studies, I determined to continue the quest by focusing on soil microbial manipulation in vegetated roofs and facades for achieving plant survival and growth promotion. After graduation, I was further intrigued to identify how beneficial microbes, together with other elements, can improve quantifiable ecosystem services produced by vegetated roofs and walls, such as stormwater management.

Urban stormwater has become a critical issue that causes damages to urban infrastructures, personal assets, and human health. Due to the difficulty in building centralized water treatment facilities in urban areas, on-site decentralized urban stormwater treatment has gained significant momentum in urban planning. It occurs to me that vegetated roofs and facades might provide on-site stormwater management. Many researchers pointed out that vegetated roofs and facades can manage stormwater, but very limited research has been conducted to confirm and quantify such ecosystem services on vegetated roofs and facades. Also, no optimizations have been carried out to improve such function.

Using vegetated facades for urban stormwater management produces many benefits. Stormwater can be stored and consumed in the system and also be reused during dry spells, achieving sustainable use of water. Besides, vegetated facades can provide many other ecosystem services, providing more livable urban environments to citizens.”

How does your research affect the world?

“This study aims to provide an on-site stormwater management solution to meet the challenge of extreme precipitation that will be more frequent in the near future. During this study, I would manipulate various related factors in the vegetated facade design to improve stormwater retention efficiency, water use efficiency, and runoff quality, meaning low nutrient and heavy metal content.

Good rainwater retention capacity of vegetated facades would significantly flatten runoff peak flow, reduce the burden of sewer systems, and reduce the likelihood of overflow. Enhanced evapotranspiration of the vegetated facade would improve water use efficiency stored in the system, providing cooling function in summer and making room for next precipitation. Nutrient and metal retention by vegetated facades would alleviate the leaching problem, decreasing the chance of urban water body eutrophication and underground water pollution.

All these benefits could not be available by building only a small number of vegetated facade prototypes. We need to transfer sciences and technologies into popular products that can be widely used. That is where InnoGreen steps in. As an established and leading greenery service company in Finland, InnoGreen has accumulated valuable practical knowledge and customers in the market. We will work together to produce marketable vegetated facade products to meet the needs of various customers.”

How will urban areas look like in 50 years?

“In 50 years, I envisage that vegetated facades will be widely built in cities and appreciated by citizens. Vegetated facades are expected to incorporate vegetated roofs and rain gardens to form a continuous greenery infrastructure that attaches to buildings. Such a greenery continuum can store, pre-treat, and recycle both stormwater and greywater on-site, achieving sustainable use of urban water resources and providing a much greener living environment.”

Picture: Eeva Murtolahti

Picture: Eeva Murtolahti

See the list of all our 2021 grantees here.