For over a century, the Assiniboine Park Conservatory has offered an urban oasis for year-round activities and connection to nature for people in Winnipeg, Canada. Officially opened in 1909, the park covers 1,100 acres (450ha), housing more than 8000 flowers, plants and trees. Canada’s Diversity Garden is the final major phase of the redevelopment of the park, which includes “The Leaf”, a facility with sub-tropical and mediterranean biodomes, a butterfly house and an adjacent building (restaurants, areas for events, classrooms and offices).
Transsolar’s concept focused on recreating the ideal growing conditions for plants, with minimal use of resources: solar access is essential as well as the passive control of the indoor conditions (air temperature and humidity). The harsh winter in Winnipeg combined with a high solar radiation challenges the desired environmental target, which requires tailored strategies for conditioning the space to guarantee the indoor targets in an energy efficient manner.
The Leaf is symbolized by a unique ETFE cable supported roof structure, which allows significant transparency and access to natural lighting whilst maintaining structural integrity. The ETFE roof developed in close collaboration by the whole team provides 50% reduction of the heating demand compared to a single pane glass because of its lower thermal conductivity.
The resulting transparent shell cultivates an immersive natural environment for visitors to experience an exotic climate. The heating demand in winter is reduced using a hydronic heating system for the roots which allows cooler indoor air temperatures overnight.
When the greenhouse needs to be cooled down or dehumidified when outside air is still below 0°C, earth ducts assisted by heating coils are used to guarantee a proper supply temperature, pre-heating the air coming from outside. Cooling demand in summer is fully met by natural ventilation and a fog system, which in addition to evaporative cooling, also controls indoor humidity levels.