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A PR IL 2018 | 27 Green Roofs The engineered media is a mix of lightweight and organic components specifically designed to use with pre-grown sedum blanket systems. It encour- ages microbial soil health, healthier plants, reduces runoff and irrigation and the potential need for syn- thetic fertilizers. The BioPocket's burst of colour, grasses and perennials are seamlessly integrated in a traditional pre-vegetated sedum blanket system. The BioPocket is placed over various depths of growing media and can help create topographic variation. There are two BioPocket styles: colour-blocked sedums-only or a com- bination of sedums and perennials. The latter requires a deeper depth of growing medium. It's the perfect solu- tion for increasing biodiversity and providing habitat and food for pollinators such as bees and butterflies. While there is of course a great deal of focus on green roofs, the impact that green walls is having is immense, and one particular company is leading the way. Nedlaw Living Walls' biofilter technology dates back to the mid-90s when the company's founder was laying foundations in the field of Biological Life Support, and has been proven time and again to be among the best and only one of its kind on the market. "We haven't fundamentally changed the prod- uct, but there are two very unique projects that truly showcase what we can achieve with our technol- ogy: Guohau Financial Tower in Ningbo, China, which is using our biofilter as a prefilter; and the Capitol Crossing development in Washington, D.C, which will incorporate a biofilter into the parking garage," says Randy Walden at Nedlaw. The Guohau Financial Tower features the world's first living wall biofilter to function as a prefil- ter. "The biofilter will clean outdoor air on demand before entering the building. Because the outdoor air quality can be so poor outside, we've designed our system to prefilter the air coming in, which hasn't been done before to our knowledge." Not only will the biofilter solution provide a higher level of indoor air quality, this solution (compared to traditional air ventilation) will use 35 percent less outdoor air. This reduction in intake air translates into energy savings for the building, as this outdoor air would otherwise have to be heated or cooled depending on the outdoor climate, before entering the ventilation stream. As with the Ningbo project, Nedlaw is also work- ing with Skidmore, Owings & Merrill (SOM) on the design of the world's first "eco-chimney" at the Capitol Crossing development in Washington, D.C. This innovative biofilter will allow post-filtration of parking garage exhaust before it reaches the sur- rounding streetscape and connected structures. According to Nedlaw designer, Laura Kennedy, the biofilter functioning as a post-filter will preserve sur- rounding public space esthetics and air quality. It's fair to say that green roofs and walls popu- larity will continue to grow, now that we better understand they are a luxury item, but a necessity to truly create a sustainable world. Of course, the sector still faces challenges, and as James Klassen at the Roofing Contractors Association of BC (RCABC) explains, "there is a suspicion among the general public that vegetated roofs are just a trend, and offer no benefits other than 'eye candy'. This may also be true for building owners, who begrudgingly pay for a vegetated roof, not because they believe in its benefits, but because building by- laws require it." Klassen agrees that climate change is probably going to have the biggest impact on current design trends. "For example, present projections for Metro Vancouver suggest that mean temperatures will gradually rise, and that we can expect longer, sus- tained high-temperature days during summer months. That will impact the kinds of plants that a roof will sustain," he says. "Sedums, as an exam- ple, do well in limited drought circumstances, but may need irrigation to sustain them if drought per- sists for prolonged periods. We can no longer assume that B.C.'s south coast summers will provide ade- quate rainfall to sufficiently irrigate vegetated roofs. Design must adapt to the probable changes." A RENDERING COURTESY SKIDMORE OWINGS & MERRILL LLP, DESIGN ARCHITECT Ningbo Guohua Financial Tower, China.

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