Innovating for Impact: Toronto Western Hospital

University Health Network’s (UHN) Toronto Western Hospital in Toronto, Canada, has been a leader in sustainable practices for over twenty years. Guided by their motto "UHN: Practicing Patient and Planet Centred Care," UHN has won multiple awards for innovative programming that incorporates care for the planet into their patient care model. 

As a further step on the path toward sustainability, Toronto Western hoped to reduce energy use and carbon emissions. To help the hospital realize that goal, UHN tapped renewable energy leader Noventa Energy Partners, famous for their groundbreaking Wastewater Energy Transfer^TM, or WET^® technology, to take advantage of thermal energy from the city’s municipal sewage system to heat and cool their campus.

WET technology replaces conventional heating and cooling systems with a heat transfer process based on recovering thermal energy from wastewater. Whereas most hospitals rely on greenhouse gas-emitting natural gas combustion to heat their facilities, the thermal energy contained in wastewater is low-carbon, highly reliable and renewable energy. 

Though most people don’t ever think about it, wastewater contains abundant thermal energy. It represents a potentially massive unused resource that only requires the will — and the expertise — to make good use of it. 

Assembling the decarbonization A-Team

As remarkable as a WET system is, it doesn’t function on its own. It requires a heat pump as a connection point between the wastewater system and the hospital’s HVAC. Noventa looked to Trane^® for that critical link. For the system to make financial sense, the heat pump must be extremely efficient. 

Another key reason Noventa chooses Trane for these large-scale projects is the depth of knowledge and capability in Trane engineering equipment and automation solutions and the quality and efficiency of the products. The expertise at Trane and the knowledge to successfully execute large and complex building automation and controls projects while integrating them into existing hospital systems allowed for efficient construction. Implementing the WET solution required working with the hospital without disrupting operations and ongoing coordination with local utilities and the City of Toronto. 

The WET technology system connects directly to Toronto’s sewer system, which remains at a stable temperature throughout the year. The system removes solids from wastewater at the sewer level, then a self-cleaning heat exchanger eliminates the need to handle wastewater inside the buildings. To integrate the recovered thermal energy into the existing HVAC system, a highly efficient, high-temperature capable heat pump is required.  

In summer, the system employs Trane chiller heat pumps containing ultra-low global warming potential (GWP) refrigerants that reject heat into the sewers. The result: the building is cooled without the need for cooling towers, which would otherwise consume energy and potable water. In winter, heat is extracted from the sewer system, and Trane chiller heat pumps supply the hospital with reliable hot water.

In addition to the heat pumps, the system leverages Trane system controls, including a Trane Tracer^® Ensemble, enterprise-wide building management system, valves and meters to control and maximize system operation. Analytics and fault detection diagnostics built into the Trane automation system manage the equipment’s performance under various conditions to ensure a reliable energy supply.

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