Guided by the ambition to celebrate Canada’s cultural and natural diversity, The Leaf is a new botanical conservatory located in Winnipeg’s Assiniboine Park. The original Assiniboine Conservancy, a brick and glass pavilion, was first constructed in 1914 and rebuilt in 1969. When it was deemed beyond repair, a new home for horticultural exploration and education was planned for the area. The Leaf is a critical part of a larger placemaking strategy to rejuvenate the more than 100-year-old park and create exciting new nature-based experiences for Winnipeggers and visitors alike.

The Leaf is an interactive destination boasting 12,000 individual plants and 400 unique species. It provides a sustainable precedent focusing on horticulture, plants, and the environment, as well as interrelationships between people. The new attraction sparks curiosity and encourages visitors to journey through four distinct biomes. The Hartley and Heather Richardson Tropical Biome is a balmy environment with a winding path brimming with tropical plants, bold textures, and vibrant colours. The Mediterranean Biome surrounds visitors with plants from regions known for vibrant fruits, fine wines, and abundant crops. The Babs Asper Display House features a rotating schedule of seasonal floral displays, and the Shirley Richardson Butterfly Garden offers a unique experience with butterflies from around the world. An all-seasons destination, visitors can also discover nature in the surrounding 30 acres of parks and gardens. The array of flora and fauna symbolizes the rich medley of cultures that exist within Canada.

The Leaf is strategically angled southwest at the edge of Assiniboine Park which was originally designed by Frederick Todd in 1904. The hallmark of the novel design, The Leaf’s roof, takes inspiration from from nature and the Fibonacci sequence. The gentle spiral net found in sunflowers and nautilus shells is extrapolated in the roof’s intricately suspended cable-net structure, which elegantly unfurls around the body of The Leaf, reminiscent of a blossoming flower. To further the design, lights within The Leaf are placed strategically on a diagrid, also known as the mast, 33 meters above grade, and reflectors hang overhead allowing the light to bounce throughout the space to replicate the effect of natural moonlight, thunderstorms, and the Northern Lights. The organic, curvilinear form echoes the simplicity and complexity of the many plant species found inside. The roof fans out from the diagrid, or mast, that contains the elevators and adjacent stairs. The space is also home to Canada’s largest free-fall indoor waterfall, measuring six storeys tall.

Unique in form, the roof also contributes to sustainability goals using Ethylene Tetrafluoroethylene (ETFE), a low-weight material high in translucency. As one of Canada’s largest ETFE buildings, it showcases a
remarkable material that has a relatively improved thermal performance compared to conventional greenhouse construction materials. Winnipeg experiences one of the most significant temperature ranges in North America - winters often see averages hovering around -40°C, summer days peak at +40°C – and addressing the extremes was a major consideration.

The ETFE roof provides a resilient and lightweight material with exceptional transparency that allows ample sunlight to reach the indoor biome and cater to the needs of the plant species housed within. Metal tubes at the top of the mast pump air between the three ETFE layers, preventing condensation and aiding in the precise temperature control needed to accommodate the building’s varied flora. The Leaf incorporates sustainable features such as natural ventilation and an open-loop geothermal system made possible by subsurface water flow, which effectively regulates temperatures within the distinct biomes. Additionally, mist fans are utilized to provide cooling for both the plants and visitors while maintaining optimal moisture levels.

The 14-hectare destination is also home to administrative offices, a multi-function event space that looks out to Assiniboine Park, a top-rated restaurant offering local fare, a teaching garden, and an entirely new tobogganing hill. The new exterior gardens and landscaping complement the interior design elements, connect the building to the outdoors, and provide opportunities for social and community interaction.

Team:
KPMB as Design Architect in association with Architecture49
Blackwell (structural), Integral Group (mechanical), SMS Engineering (electrical), HTFC Planning & Design (landscape), KPMB Architects and Architecture49 (interiors), Bird Construction (contractor), Transsolar Inc. (energy & climate), Vector Foiltec (ETFE systems), KGS Group (civil), Soberman Engineering (vertical transportation), LRI Engineering (code), Mulvey & Banani International Inc. (lighting), Lord Cultural Resources (interpretation and visitor experience), DEW Inc. (water feature design), Aercoustics Engineering Ltd (acoustics), Altus (quantity surveyor)

Photography: Ema Peter Photography, Richard Seck