In Winnipeg’s Assiniboine Park, The Leaf is a new botanical sanctuary for the 21st century designed by KPMB Architects in collaboration with Architecture59, Blackwell Structural Engineers, and HTFC Planning & Design. The ambitious project aims to promote a greater appreciation and understanding of the botanical world while celebrating Canada’s cultural diversity by playing a role in how communities perceive, interact with, and understand nature and sustainability. The project is particularly notable for a spectacular translucent roof made of resilient, lightweight ethylene tetrafluoroethylene (ETFE).
The Leaf houses four biomes with over 400 unique plant species alongside amenities such as a restaurant and coffee bar. Visitors begin at the Hartley and Heather Richardson Tropical biome, which features a meandering pathway that encourages visitors to explore the exotic species. Following this, the Mediterranean Biome brings together colours, textures, and fragrances of native plants from Greece, Italy, South Africa, and Chile. Meanwhile, the Babs Asper Display House features the art of horticulture with a rotating schedule of dynamic floral displays that explore seasonal and global themes and change four to five times per year. Finally, the Shirley Richardson Butterfly Garden includes a canopy that wraps around a waterfall feature and overlooks the Tropical Biome. The impressive waterfall, over 60 feet in height, was designed by Canadian artist and landscape architect Dan Euser.
The Biomes are housed by a cable net structure that forms a roof reminiscent of a blossoming flower. The organic form of the conservatory roof design references the simplicity and complexity of the natural world, its geometry drawing from the Fibonacci sequence, particularly nautilus shells, and sunflowers.
The roof is made of ethylene tetrafluoroethylene (ETFE), a resilient, low-weight material with a high degree of transparency as required to sustain the plant species contained within. EFTE also has a relatively improved thermal performance compared to most conventional greenhouse construction materials, which is particularly appropriate here, given that Winnipeg experiences one of the most significant annual temperature ranges in North America.
“For The Leaf, we wanted to create a transcendent experience that centers on nature and sustainability. We wanted to do something innovative, something extraordinary, that could be enjoyed year-round in a city with extreme climates. The structure is inspired by nature, with a roof that unfurls like a petal, and the diverse biomes inside encourage curiosity, learning, and delight at every turn. The architecture goes beyond a mere place to house and showcase these climate biomes. The building itself is designed as an ode to the beauty of nature so visitors can feel the respect for the earth and environment from the very first look,” says Mitchell Hall, KPMB Partner.
The Leaf also incorporates sustainable features such as natural ventilation and an open-loop geothermal system made possible by subsurface water flow, effectively regulating temperatures within the distinct biomes. Additionally, mist fans are used to provide cooling for both the plants and visitors while maintaining optimal moisture levels.
The Leaf is surrounded by 30 acres of public gardens and greenspace divided into six unique themes: Indigenous Peoples Garden, Kitchen Garden, Sensory Garden, Performance Garden, Seasonal Garden, and The Grove. Thanks to the high transparency of the biomes, a strong sense of both visual and physical connection is created between these new exterior gardens and the indoor realm.