Later this year, Austin, Texas-based Rastegar Property Company will break ground on a 26-storey apartment complex in Dallas’ ‘Emerald Bracelet‘, a loop of green space through the city’s central district.
The residential property will add a pocket park that extends vertically up the tower, which the developers claim will create the tallest living wall in North America. Rastegar is teaming up with Chicago-based green design firm Zauben to create the green wall, which will contain approximately 40,000 plants adapted to the Texas climate.
Long live living walls
Long popular in Europe and Southeast Asia, living walls have only recently become trendy in the United States, according to Zauben CEO Zach Smith, as designers and developers look for innovative and aesthetically pleasing ways to meet greener building standards. In the last few years, a wave of green roof mandates has swept through cities across the country, from San Francisco to Denver to New York.
For Rastegar, sustainability is part of its ethos, according to the company’s Vice President of Real Estate Josh Eadie. To this end, green walls and rooftops can provide countless environmental and economic benefits.
Living walls can act as insulators, keeping buildings cool in the summer and warm in the winter. They can cut down on energy consumption and costs. They can absorb stormwater, reducing flood risk. Finally, living walls can counter the urban heat island effect, whereby asphalt-coated cities absorb more radiation from the sun, becoming significantly warmer than their rural counterparts.
‘If you were to take Manhattan, and you were to trade the glass skyline for green rooftops, you would lower the temperature of the entire city by as much as 8 degrees’, Smith said.
Fighting air pollution
Living walls can also help cities combat air pollution. The plants can filter the air indoors and out, pulling carbon dioxide, nitrogen dioxide and particulate pollution out of the atmosphere.
Dallas has a lot of pollution.
Texas emits more carbon dioxide than any other state, according to the U.S. Energy Information Administration. Dallas, the state’s largest metropolitan area that also includes the city of Fort Worth, is one of the most polluted areas in the country. Texas, however, has taken on significant work to clean up its air; the number of high ozone days in Dallas county have been falling over the last two decades, according to the American Lung Association.
Nevertheless, rising temperatures can boost the formation of ozone, undermining Texas officials’ hard-fought gains. Climate change will make cleaning up the air even harder for the city.
When it’s installed, the building’s living wall’s 40,000 evergreen plants are expected to produce 1,200 pounds of oxygen every year, while removing about 1,600 pounds of carbon dioxide from the atmosphere. That’s equivalent to burning just more than 300 litres of petrol – a drop in the bucket for Dallas’ car-centric culture and transportation infrastructure.
The plants will grow in mineral wool, a soil of volcanic rock that holds onto moisture, so the wall will require watering less frequently. The wall will also be equipped with Internet of Things technology – an array of sensors that collect data on soil and plant health as well as moisture and sunlight, which can be used by landscapers for targeting plant care.
The building’s developers know that even the tallest living wall in North America won’t solve the city’s air-pollution problem. But they hope it can help, while serving as an example of what’s possible for future green buildings.
‘We hope that we are a trendsetter’, Eadie said.
Adding living walls and rooftops to structures can still be a pricey endeavour that involves high upfront installation costs and careful maintenance. But Zauben said it has developed systems that make living walls at this scale both physically and economically feasible.
Rastegar said it’s confident that city dwellers will likely associate a premium with the shot of nature, which research shows is good for both physical and mental health.
‘It makes sense from a business perspective in addition to a social responsibility perspective’, Eadie said.