May 13, 2025
Positioned within Winnipeg's expansive 1,100-acre Assiniboine Park, The Leaf, designed in collaboration with KPMB Architects, is an iconic attraction that invites visitors into a world where architecture and the beauty of nature intertwine. Its four distinctive biomes, complemented by a classroom, restaurant, café, and banquet facilities, offer a captivating experience that fosters a profound connection between people and plants.
This iconic landmark has now earned LEED Gold certification through the LEED 2009 BD+C Rating System, marking a significant milestone and adding to its list of accomplishments. With an impressive 63 out of 110 LEED points, the Leaf excelled in Energy Performance (16/19 points), Low Emitting Materials (4/4 points), and Alternative Transportation (12/12 points). This achievement underscores the commitment to environmental responsibility and innovation in sustainable architecture.
Sustainability in conservatory design
Sustainability was a core objective for the Leaf, championed by Assiniboine Park Conservancy’s Sustainability and Education teams. One of the most formidable challenges was establishing an appropriate benchmark for energy efficiency, as no existing LEED standards or energy codes specifically addressed conservatories.
Traditional North American greenhouses rely on single-pane glass or polycarbonate panels, which let in plenty of sunlight but also have poor thermal resistance, demanding massive mechanical systems to maintain temperature. The Leaf took a different approach, strengthening its thermal envelope with ethylene tetrafluoroethylene (ETFE). The ETFE system consists of two layered pillows which are inflated with air to create a thermal resistance much higher than a single pane of glass without sacrificing transparency. ETFE is also very light-weight, allowing for large transparent spans and massive volumes for the vegetative growth with minimal shading from structural members. Avoiding creating shadows within the garden spaces allows for maximum plant growth. By reducing the need for heavy framing, ETFE allowed for an open, light-filled environment that supports plant growth. Passive design strategies, such as maximizing natural light and minimizing heat loss, further contribute to energy efficiency. To create a more self-sustaining ecosystem, The Leaf incorporates a dry fog system , helping to regulate humidity, and to create an immersive environment conducive to sub-tropical plant growth.
Plant and wildlife health
The Leaf’s design carefully balances temperature, humidity, daylight exposure, and UV light in three uniquely distinct biomes to create optimal conditions for Subtropical plants, Mediterranean plants, and exotic butterflies. A root heating system supports plant health by maintaining warm root temperatures, allowing ambient air to fluctuate naturally between day and night. The Leaf’s immersive experience transcends the visitor into another environment which includes sunlight, wind that is generated from displacement of air by the waterfall, and mist/clouds which is generated by nebulized water. The wind not only strengthen plant roots but also help prevent vegetative molds and control pests.
A main street between environments
Bridging the gap between the traditional "box building" and the conservatory, the Leaf’s ‘Main Street’ is designed as a welcoming space for visitors and staff alike. A radiant heating and cooling slab stabilizes temperatures, while targeted spot cooling and heating enhance comfort for staff. A unique dry-fog system, created by fog nozzles and high-speed fans, introduces a cooling breeze, allowing for warm temperatures without unacceptable discomfort.
Repurposing the past
When the Leaf was built, Assiniboine Park Conservancy made sure the decommissioning of the old Conservatory was handled with care. Glass from the original structure was crushed and incorporated into the new building’s second-floor concrete slab, giving it a distinctive blue shimmer. Even trees removed during site clearing found new purpose; trees were repurposed into millwork and artisan pieces, some of which are now available at the Leaf’s gift shop, offering visitors a chance to take home a piece of history.
Enhancing accessibility and green transportation
The Leaf’s dedication to sustainability extends beyond its walls, transforming how visitors engage with the site. Thoughtfully designed pedestrian pathways make public transit access easy year-round, while bike lockers, EV charging stations, and preferred parking for high-occupancy vehicles encourage greener transportation choices.
The Leaf at Canada’s Diversity Gardens isn’t just a conservatory, it’s a testament to what’s possible when innovation, sustainability, and environmental responsibility come together. By challenging conventional construction techniques and rethinking the way that humans and plants can thrive together in and indoor environment, the Leaf sets a bold new standard for conservatories worldwide. As a beacon of green architecture, it not only provides a thriving space for plants but also inspires visitors to embrace sustainability in their own lives.