Vertical gardens, or ‘green walls’, have become a popular feature for new buildings, though until now they have always been more of an accent piece—typically reserved for just one wall or a small section of one at most (rapper Lil’ Wayne bought a Miami house with one as just one example). That is all about to change with the influx of several different technological advances.
A development in Dallas is said to be creating the largest green wall in North America on the side of a 26-story condominium building. The rendering below shows the new build will have an estimated 40,000 plants, most of which are evergreen species since they stand up well to extreme temperatures. The Internet of Things, or IoT technology, is what will make this possible. Sensors which measure soil health, moisture levels and sunlight exposure will send data to an app the landscaping team uses to monitor the entire wall so they can know if any changes need to be made before the plants start to suffer. Rastegar Property Company, the team behind the project, estimates the vertical garden will absorb 1,600 pounds of carbon dioxide and produce 1,200 pounds of oxygen annually. The soil, called mineral wool, is derived from a volcanic rock and needs much less water to support healthy plant life.
Researchers at The School of Civil Engineers of Barcelona (UPC-BarcelonaTech) have concepted a ‘living concrete’ which can not only be used as a construction material but also as a substrate for moss, microalgae and lichen to thrive upon. Also called ‘bioreceptive concrete’, the multi-layered material begins with a stratum that provides the structural foundation to the building. After that comes a waterproof layer to prevent the moisture from the outer layers seeping into the concrete. On top of this is the biological layer where the vegetation can grow. Finally there is a coating of material which lets rain water in but has a ‘reverse waterproofing’ design so enough of it will stay in the biological layer. You might notice there isn’t any soil involved in the process. Ignacio Segura, one of the researchers on the project, explains:
“The bioreceptive concrete allows microorganisms to colonize the façade by using a combined approach. The material uses a low-pH cement, magnesium phosphate cement, to allow biological growth. Furthermore, the material is specifically designed to enhance the surface roughness and the porosity to enhance water retention and ease biological colonization.” Antonio Aguado and Sandra Manso were two other researchers involved in the project.
Another developer, in the dry climate of Arizona no less, has come up with a vertical planting system that has self-contained irrigation and drainage so plants can grow up and over the side of the building. This provides a natural shading system while also creating cleaner air and decreasing the excessive temperatures so common to Arizona. Vertical gardens are one part of their overall greening initiative which aims to be carbon neutral by 2030.
A few years ago green walls were considered an elaborate and expensive endeavor. Pumping water up to the top of a building to keep the plants watered was a complex affair. But now with sensors that can alert your phone or hydrophilic material that can adhere to concrete there is every chance this will become much more feasible to implement. It could also help lower the heating costs of a building since it decreases the ambient temperature in the surrounding air. I expect we’ll soon start to see more green walls cropping up around the country.