Roof Talk-101 There Are Green Roofs and Then There Are Smart Green Roofs

Green Roof

Rob O'Flanagan,Mercury staff

Youbin Zheng, University of Guelph School of Environmental Science associate professor and chair in Environmental Horticulture, is developing a new kind of green roof that uses smart technology. A partnership between U of G and global software company SAP is seeing the system being tested on local rooftops, including here on Skyline's Gummer Building.

ByRob O'Flanagan

GUELPH — There are some growing roofs in Guelph — one over a Hillside Festival stage, another atop city hall. But the University of Guelph and the global software company SAP are taking the concept up a high-tech notch.

Together they are conducting research and development on 'smart' green roofs — roofs made from special plants and special soil that absorb storm water, regulate building temperatures, and use automated monitoring and maintenance systems.

If widely used, the roofs could vastly reduce air conditioning costs and storm water management costs, and prolong the life of roofing decks, developers of the concept say.

Guelph's Gummer Building, headquarters of Skyline Group of Companies, is growing one of two pilot roofs in the Guelph area. The other is on a farmhouse north of Ariss.

The idea was developed by Youbin Zheng, University of Guelph associate professor in the School of Environmental Science, and chair of the Environmental Horticulture and Vineland Research and Innovation Centre.

Zheng was up on the Gummer Building roof recently conducting a quick overview of downtown Guelph rooftops, pointing out that when a hard rain falls, all the water runs off roofs, down streets and into storm drains. When torrential rains fall, as they did in Toronto and Calgary over the summer, systems become overloaded.

"It costs tons of money to manage storm water," said Zheng, who was joined on the roof by research associate Greg Yuristy, and U of G Catalyst Centre industry liaison Tyler Whale. The Catalyst Centre is working to commercialize the smart green roof.

The green roof, Zheng said, can eliminate vast amounts of storm water by absorbing heavy rains and using them to nourish carbon absorbing plants. Not only do the roofs have the potential to reduce municipal infrastructure costs, they act as very efficient insulation, reducing air conditioning costs by up to 75 per cent.

The artificial soil the plants grow in can incorporate waste materials, such as crushed bricks or even crushed zebra mussels, he added.

SAP's Waterloo office is partnering on the project. Bob Campagnolo is SAP Canada's consultant in the emerging technologies group.

"We want to make the performance of the green roof and the maintenance of it as automated and as easy as possible," he said.

Sensors of all kinds have become ubiquitous in society, he said, and SAP wants to take advantage of the technology to remotely monitor the health of a green roof.

"Typically green roofs are installed and there might be some sort of manual maintenance procedures in place to make sure the roof remains healthy," he said. "What we're going to do is automate that."

Various sensors, some of which are solar powered, will measure a number of variables that contribute to the health of the roof, including sunlight, temperature and humidity, nutrient levels and soil moisture.

"They'll transmit that data to a consolidation point, and the availability of the data from the sensors allows you to track the performance of the roof remotely," Campagnolo said. "Not only will the data tell you if you need maintenance, but we can automate the maintenance as well."

Jason Ashdown is chief of operations with the Skyline Group. He said his company, SAP and the university want to know if the green roof will cost roughly the same as conventional flat roofs. There are indications the costs will be comparable, and if that is the case the green roofs may be a viable alternative for the company, which is one of Canada's largest multi-residential real estate owners.

"We decided to try it on one of our newest buildings, join up with the U of G and see how it looks and how it works," Ashdown said. "We'll make judgment on it in a year or so."

With three million square feet of commercial roof surface, the company spends a great deal on roof repair and replacement, Ashdown said. If a green roof can cut down on those costs, it will be a financial benefit to the company.

"We like to do things that help the environment and reduce our footprint," he added.

Tyler Whale, of the Catalyst Centre, patents and markets U of G innovations. He said the Skyline roof in downtown Guelph is the first smart green roof project on a flat roof.

"Having Skyline as part of the team is really nice," he said. "They are a local company that cares about trying to advance research and development within their community, and within the environmental sustainability framework, and at the same time save money. These are business people who want to make the right choice and make their business more profitable. This is one of those technologies that can do that."

Whale said smart green roofs make good business sense because they prolong the life of roof decks on buildings and improve the efficiency of solar panels.

Work remains to be done on the data collecting system and the structure of the roofs, Campagnolo said. Roughly another year is needed on the research and development stage, and other early adopter customers will have to be lined up before the system goes commercial.

Green roofs replace conventional roofing material, such as asphalt shingles or tin. A layered system, a green roof begins with a waterproof membrane, followed by a drainage layer, a layer to keep dirt and grit out of the drainage layer, the artificial soil and the plants themselves.

The plant sedum is often used on green roofs because of its water retention properties, but water evaporation, necessary for keeping roofs cool, is not one of sedum's strengths, Campagnolo said. U of G scientists are studying other plant combinations that would be more effective.

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