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Sumit Singhal
Sumit Singhal
Sumit Singhal loves modern architecture. He comes from a family of builders who have built more than 20 projects in the last ten years near Delhi in India. He has recently started writing about the architectural projects that catch his imagination.

NPS Podium Roof Garden in Toronto, Canada by PLANT Architect, Perkins Will Canada, HSLA and ABUP

August 4th, 2011 by Sumit Singhal

Article source: PLANT Architect, Perkins Will Canada, HSLA and ABUP

Project update – December 22, 2011 – The Nathan Phillips Square Revitalization Podium Green Roof Garden has won two more Awards!!

  • Green Roofs For Healthy Cities 2011 Award of Excellence
  • DX Silver Award

The Podium Green Roof Garden is the first transformation in the competition-winning scheme “Agora Theatre” –  the Nathan Phillips Square Revitalization. This three-acre upper-level component of Viljo Revell’s 1965 iconic City Hall and multi-level public square was originally conceived as a ceremonial public space, reached via a giant sculptural ramp. The space was never successful at attracting the public – it was a grim, empty, three acres of concrete that has been closed to the public for well over a decade. The Podium Green Roof Garden re-conceives this upper level as a vast public park integrated with the existing elevated walkway system, and while respecting the complex’s heritage status, reopening it to the public as a truly engaging 21st Century space. The project reconsiders how an extensive green roof providing a plethora of technical environmental benefits can be an exciting and successful public space that merits repeated, habitual visits. It is the largest publicly accessible green roof in Canada and the flagship green roof project for the City of Toronto that since 2009 mandates green roofs on all new buildings. By creating a vital community space that fulfils this environmental imperative, it promotes a broader concept of stewardship linking people to their environment.

Night View (Images Courtesy Steven Evans and Chris Pommer)

  • Architect: PLANT Architect, Perkins Will Canada, HSLA and ABUP
  • Name of Project: NPS Podium Roof Garden
  • Location: Toronto, Canada
  • General Contractor: Flynn Canada / Gardens in the Sky
  • Structural: Blackwell Bowick Engineering
  • Mechanical/Electrical: Crossey Engineering Ltd.
  • Photos: Steven Evans and Chris Pommer

Night View (Images Courtesy Steven Evans and Chris Pommer)


  • PLANT: Chris Pommer, Lisa Rapoport, Mary Tremain, Elise Shelley, Vanessa Eickhoff, Lisa Moffitt, Jane Hutton, Heather Asquith, Lisa Dietrich, Suzanne Ernst, Jessica Craig, Jeremy McGregor, Matt Hartney;
  • Perkins Will Canada:  Andrew Frontini, D’Arcy Arthurs, Linda Neumayer, Perry Edwards, Gavin Guthrie;
  • HSLA: Peter Schaudt, John Ridenour;
  • ABUP: Adrian Blackwell, Marcin Kedzior; James Urban; Blanche Lemko van Ginkel.

Images Courtesy Steven Evans and Chris Pommer

Working within the heritage designation, the project fulfils the original potential of Revell’s weakly designed space as a public space adjunct to the main square, as a place for ceremony, and as a place to get up close to the fine detail of the city hall buildings. New potential is brought by offering a garden respite from the harsh concrete downtown environment, which is formally complex and lush, with an abundant variety of colour and texture, with places for intimacy and lingering, for lunch and evening strolls, for art installations, and to technically improve the building and environment by contributing to energy efficiency, roof membrane longevity, sound insulation, air filtration, storm water management, and habitat creation.

Images Courtesy Steven Evans and Chris Pommer

The half kilometre walk reveals the passage of time at different scales. The shade structures mark the movement of the sun over the course of the day, their shadows aligning with benches at specified hours from 10am-2pm. There is something new blooming in different parts of the garden from April to October, marking seasonal change. The initial garden layout is rigid, but the plants will shift and move naturally blurring the geometry into a more Fauvist set of drifts as the years pass.

Images Courtesy Steven Evans and Chris Pommer

Technical accomplishments include the tower lighting energy reduction from 110,000 watts to 7000 watts (LED’s at full intensity – the lights often use only half of this capacity). 12% of the vast City Hall block is transformed from concrete to planting, providing 4000m2 more oxygen producing, storm water-retaining, bee and butterfly attractive area to the city centre. The renovation of the entire complex is targeting LEED gold.

Images Courtesy Steven Evans and Chris Pommer

The site’s popularity is demonstrative – it is used daily dawn to dusk for lunching, strolling, (and lovers!). 100,000 people came to the opening at Doors Open and hundreds took the guided tours. Councillors do their interviews there, just married couples take their photographs there, and CTV local news promotes Toronto there. Nuit Blanche 2010 staged two installations on the podium, and plans many more. It has been successful in dispelling the notion that green roofs are just green carpets. Media postings from Tree Hugger to the Globe and Mail have praised it as “an oasis”, “leading by example” and the Globe says it is “a stunning overhaul of the long-abandoned podium roof – [is] so impressive in its landscape detail and magnetism that it warrants the drop command: Drop everything and go directly to it”.

Images Courtesy Steven Evans and Chris Pommer

The park consists of a lush perimeter garden surrounding the towers, a sparkling black granite paved courtyard that frames the Council Chamber, and a striped café deck that occupies the prow.

Images Courtesy Steven Evans and Chris Pommer

The garden is a journey around the close-knit ensemble of the council chamber and towers. Inspired in part by Paul Klee’s Polyphony, the garden is planted with a complex mosaic of 23 sedum species inter-planted with 42 species of grasses, alliums and bulbs. The colours subtly shift, progressing from brighter yellows and oranges in the SW to reds and purples in the NE – responding to shade and wind conditions created by the towers. A pre-vegetated tray system (4” and 6” depths) was used for easy installation, and to facilitate future maintenance with sedums forming the base layer to suppress weeds. The depth of the trays is concealed to provide a seamless surface of planting.

Images Courtesy Steven Evans and Chris Pommer

A wide walk runs around the perimeter and another runs tight to the base of the towers ­– Torontonians are just discovering after 45 years that the towers are clad in Carrara marble! Cross walks join these two circuit walks with quiet seating areas nestled among the plants. Paving materials include custom concrete planks, stabilized crushed calcite walks, and crushed black granite borders. LED lighting is concealed under benches and in the new perimeter ipe guard rail.

Images Courtesy Steven Evans and Chris Pommer

The black granite courtyard recalls Revell’s original reflecting pool (removed early on due to leaks) and with its animating light sticks, provides spill out from the wedding chapel and arts programming day and night. The prow supports large gatherings with its in-ground LED slit lights and is pre-plumbed for a future food kiosk. The large raised tree planter with its 3 Kentucky Coffee Trees (mature height 40+’) will provide shade, and finally beckons people up from the main square to come and enjoy their new park.

Images Courtesy Steven Evans and Chris Pommer


NPS Podium plan

NPS Podium Seasonal Planting Plans - SPRING

NPS Podium Seasonal Planting Plans - SUMMER

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Categories: Garden, Land Preserve

2 Responses to “NPS Podium Roof Garden in Toronto, Canada by PLANT Architect, Perkins Will Canada, HSLA and ABUP”

  1. SAM says:

    wonderful and beautiful.

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    It is a popular alternative to the drain mats , so long the practice in the U.S. Drain mats clog up.

    One a remedy, the other a cause.

    George McCord
    Let us know of your interest or upcoming projects for sample.

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