Not content with having the largest non-industrial living roof in Canada and North America, designers in Canada have gone one step further with the completion of the largest and most biologically diverse living wall in North America. Green wall designers Green Over Grey recently completed work on the living wall at the Semiahmoo Public Library and Royal Canadian Mounted Police Facility in Surrey, British Columbia, which consists of a unique design covering nearly 3,000 square feet (279 square meters) and consisting of over 10,000 individual plants.

A living wall is a self-sufficient hydroponic vertical garden attached to the exterior or interior of a building. The Green Over Grey living wall frame with waterproof panels is built and attached to a wall at a fixed distance, allowing air circulation and no damage to the building. This frame contains lights and an automatic irrigation system, and the plants receive water and nutrients evenly from this and the lightweight porous material that the plants are embedded in. The plants grow well in the vertical structure as it mimics natural growth on cliffs, trees, and next to waterfalls. Plus it adds beneficial insulating, rain-screening and air purifying benefits to the building itself. In fact, its designers say it may reduce electricity bills in winter by up to 20 percent and reduce temperatures in summer by as much as 7°C (12.5°F).

Other benefits are improved health and well-being for employees and visitors, improved aesthetics, and an increase the property value – especially if it is awarded LEED credits. All plants absorb and clean pollutants from the air but Green Over Grey also uses efficient air-purifiers in addition to the wide selection of ground covers, large perennials, shrubs and small trees from 120 unique species used to create the unique design. Furthermore the green walls are low maintenance and water efficient thanks to the automated irrigation system, especially when compared to normal plant watering in gardens and urban parks. This is because the only water lost is through evaporation and transpiration, not leaching away through the soil. And without soil, there are no soil-borne pathogens.

"The large diversity of plant species chosen creates a balanced ecosystem that is an urban oasis for bees, butterflies and hummingbirds," says Patrick Poiraud, Principal at Green over Grey – Living Walls and Design, the Vancouver-based company that designed and constructed the wall. “The initial inspiration for this garden came from the artwork of the Coast Salish (including Semiahmoo) First Nations People," adds designer and artist Mike Weinmaster of Green over Grey.

"This will be our first large-scale green wall in Surrey," says Mayor Dianne Watts. "It will be a beautiful living work of art that will cover the existing concrete wall and provide many environmental benefits, including saving energy, reducing greenhouse gas emissions and creating a new ecosystem in the heart of Semiahmoo."

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