Written by: Allison BrownÂ
Edited by: Sonja Colford
In the heart of Canada’s bustling financial capital, an innovative system is quietly revolutionizing the way buildings are cooled. The deep lake water cooling (DLWC) system used in Toronto is the largest one of its kind, offering a new sustainable option for keeping the city cool. DLWC is used to control the temperature of over 100 buildings and saves enough electricity to power a town of 25,000 (Root, 2021). As the effects of climate change intensify and urbanization grows, sustainable and environmentally conscious solutions, like DLWC, become increasingly important to incorporate into urban planning and infrastructural projects.
DLWC is a system that uses the naturally cold water from the deepest areas of lakes in order to provide sustainable air conditioning for buildings. In Toronto, the system harnesses the cold water from Lake Ontario, a resource readily available due to the lake's vast size and depth. The concept is simple but effective: water from deep in the lake, where temperatures remain consistently cold year-round, is drawn through a network of pipes and used to cool air in buildings (Israelson, 2024).
Toronto’s deep lake water cooling system is operated by Enwave Energy Corporation, who pride themselves on being a company providing innovative energy solutions. The process begins with water intake pipes positioned at a depth of approximately 83 meters in Lake Ontario, where the temperature hovers around 4 degrees Celsius. The cold water is pumped to a central facility, where heat exchangers transfer its cooling properties to a closed-loop distribution system that serves buildings across downtown Toronto. Importantly, the lake water itself is not directly circulated through the buildings but is returned to the city’s potable water system, ensuring efficacy and sustainability.
One of the most significant advantages of DLWC is its environmental impact. Traditional air conditioning systems rely heavily on electricity and refrigerants, contributing to greenhouse gas emissions. In contrast, deep lake water cooling systems use significantly less electricity, reducing energy consumption by up to 90% compared to conventional cooling methods (Enwave, 2021). This reduction is particularly crucial in cities like Toronto, where high-rise buildings and commercial complexes dominate the skyline and contribute to peak energy demand during the summer months.
Deep lake water cooling also reduces the urban heat island effect, a phenomenon where cities experience higher temperatures than surrounding rural areas due to human activities and infrastructure (Climate Atlas of Canada, n.d). By minimizing the heat released into the environment, deep lake water cooling helps to mitigate this effect and contributes to a more comfortable urban climate. Moreover, the system’s reliance on Lake Ontario’s natural cooling capacity ensures a steady and reliable energy source. As global temperatures rise, the demand for cooling will only increase, making sustainable solutions like DLWC essential for long-term urban resilience.
Toronto’s deep lake water cooling system is among the largest in the world, serving over 100 buildings in the downtown core, including iconic landmarks such as the Royal Bank Plaza, the TD Center and Toronto’s very own City Hall. The system’s capacity to cool millions of square feet of office space has made it a model for other cities exploring sustainable energy solutions.
The initiative began in the early 2000s as part of Toronto’s broader efforts to address climate change and reduce greenhouse gas emissions. Enwave partnered with the city and private stakeholders to develop the infrastructure needed to bring DLWC to life. Today, the system saves approximately 90,000 megawatt-hours of electricity annually, equivalent to taking 15,000 cars off the road each year (City of Toronto, 2023).
Despite its numerous benefits, deep lake water cooling does not come without its own challenges. One primary concern is the upfront cost of building the infrastructure. Installing intake pipes, heat exchangers, and distribution of networks requires significant investment, which can be a barrier for cities looking to adopt this technology (Root, 2021). Another consideration is the potential environmental impact on aquatic ecosystems.
Drawing large volumes of water from a lake can disrupt habitats if not managed carefully. However, in Toronto’s case, the system is designed to minimize such effects. The intake pipes are located at depths where aquatic activity is minimal, and the water returned to the lake is treated to ensure it does not harm the ecosystem (Root, 2021). Finally, the success of DLWC systems depends on proximity to cold water sources, limiting its applicability to cities near deep lakes or oceans. For Toronto, the presence of Lake Ontario is a unique advantage that many urban centers cannot replicate.
The success of deep lake water cooling in Toronto has inspired other cities worldwide to explore similar solutions. In North America, cities like Chicago and Boston have implemented smaller-scale systems, while international hubs like Stockholm and Helsinki have integrated deep water cooling into their urban planning (Gualtieri & Pohjanpalo, 2022).
Toronto’s example also highlights the importance of public-private partnerships in driving sustainable innovation. By collaborating with companies like Enwave, the city has demonstrated how governments and businesses can work together to address climate change challenges while delivering economic benefits. The system has created jobs, attracted investments, and enhanced Toronto’s reputation as a leader in sustainability.
Looking ahead, there is potential to expand the reach of DLWC in Toronto. As the city continues to grow, integrating more buildings into the system could further reduce energy consumption and emissions. Advances in technology may also make it feasible to extend the system to areas farther from the lake, increasing the breadth of its impact.
Deep lake water cooling is a shining example of how cities can leverage natural resources to create sustainable, efficient infrastructure. In Toronto, this innovative system has transformed the way buildings are cooled, reducing energy consumption and greenhouse gas emissions.
As the world grapples with the dual challenges of climate change and urbanization, solutions like deep lake water cooling offer a blueprint for a sustainable future. By investing in technologies that prioritize efficiency and environmental stewardship, cities can pave the way for healthier, more sustainable communities. Toronto’s experience serves as a powerful reminder that when innovation meets collaboration, the possibilities are endless.
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References:
City of Toronto. (2023, October 5). Deep Lake Water Cooling Supply expansion. https://www.toronto.ca/community-people/get-involved/public-consultations/infrastructur e-projects/deep-lake-water-cooling-expansion-study/ Â
Enwave. (2021, December 8). What is the worlds’ largest deep lake water cooling system like? Resources : What is the worlds’ largest deep lake water cooling system like? - Enwave Energy Corporation.Â
Gualtieri, T., & Pohjanpalo, K. (2022, October 18). Helsinki utility finds a surprising heat source: Icy Seawater. Bloomberg.com.Â
https://www.bloomberg.com/news/articles/2022-10-18/helsinki-utility-finds-a-surprising heat-source-icy-seawater
Israelson, D. (2024, April 2). The world’s largest deep lake water cooling project just got bigger. The Globe and Mail.
https://www.theglobeandmail.com/business/industry-news/property-report/article-the-wor lds-largest-deep-lake-water-cooling-project-just-got-bigger/Â
Root, T. (2021, November 5). Toronto is home to the world’s largest lake-powered cooling system. Here’s how it works. The Washington Post .Â
https://www.washingtonpost.com/climate-solutions/interactive/2021/toronto-deep-latke water-cooling-raptors/
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Climate Atlas of Canada (n.d) Urban heat island effect. Climate Atlas of Canada. https://climateatlas.ca/urban-heat-island-effectÂ