This week I stood on the freshly greened roof of the Toronto-Dominion Centre banking pavilion, surrounded by a field of creek sedge grass. Bounded on all sides by steel and concrete skyscrapers, the oasis was surreal and thrilling. It felt strangely illicit – as if a tract of farmland had been floated down on the city's financial district.

The transformation of heat-absorbing asphalt roof-scapes into energy-saving canvases of greenery is being embraced not only by businesses, but university and condominium developers. Living roofs are also increasingly being promoted as therapeutic tools for health-care facilities. There are courtyards at CAMH on Queen Street West, an extensive fragrant garden at the CNIB, and the Royal Victoria Health Centre in Barrie has just installed nine green roofs.

In Toronto's west end, the Lakeshore Lodge, a city-owned long-term care facility, has enhanced its roof terrace to provide shade for its 150 residents while providing them with fragrant and textured plants that stimulate their senses.

Story continues below advertisement

"The evidence-based research is very clear that looking at nature assists with healing process," says Viive Kittask, an associate at Vertechs Design Inc. and the project landscape architect on the recently opened terrace at Lakeshore Lodge in Mimico. "Plants and shrubs can orient the elderly in time, helping them to be aware of what season it is."

The TD Centre, one of the urban masterworks by architect Ludwig Mies van der Rohe with John B. Parkin and Bregman & Hamann, is a stellar complex of vintage modernism from the 1960s, but the roof was beginning to show its age. Minor leaks were starting to spout. Determined to continue as the major tenant within the black-steel complex, TD decided to cover the cost of the reinvented roof for its iconic podium bank.

The creek sedge grass has been planted in 690 low-lying aluminum frames lined up according to a strict Miesian grid designed by B + H Architects with Flynn Construction. Green Reason, a sustainability consultant, managed the environmental protocols.

Compared to a conventional, asphalt tile roof, the green one with a built-in misting system costs about 30 per cent more to construct. But there are many benefits: the insulation value has been immediately increased from R5 to R25 (which will significantly reduce heating and cooling bills) and, says Michael Parker of the TD's energy and environmental architecture and design unit, "the birds have started to land here." Like any other living roof, the new field of sedge grass at TD is powerful enough to clean some of the carbon dioxide from the air. It will capture rainfall and use it to irrigate the soil beds.

Although the TD rooftop will not be accessible to the public, a video feed will allow viewers to watch the progress of the sedge grass.

What might Mies have said about the greening of his rooftop? He typically designed his buildings with strictly measured repeating modules. The tightly ordered geometry of the planters mirrors the ceiling grid inside with its coffered ceiling detail.

Throughout his career, he endorsed the use of luxurious materials such as green Tinos marble and English brown walnut, and materials of the age: bronze-tinted glass and black steel. Now that nature is becoming the brush of choice, Mies might have agreed that, beside his famous maxim 'less is more,' green is core.

Story continues below advertisement

For more on great design ideas from around the world, follow Lisa Rochon's blog, chasinghome.org