Page 7 - U4SSC Case study: Energy efficiency in buildings, June 2020

Deep lake water cooling: its origins and the next evolution

Author: Catherine Thorn

Introduction

Background

Toronto is Canada’s largest city and continues to grow at a staggering rate (City Planning Division, 1).
In January 2018, the city earned the unique title of having the highest crane count in Rider Levett
Bucknall’s crane index (RBL, 3), an indicator of high-rise construction activity in North American cities.
This rapid growth comes with opportunities and challenges. Economic growth exerts more pressure
on Toronto’s already constrained electricity grid (Central Toronto Area Integrated Regional Resource
Plan, 1) and makes it harder to reduce total greenhouse gas (GHG) emissions; however, it also provides
Toronto with the scale and resources to invest in transformative strategies.

The Economist has highlighted Toronto as one of the ten most liveable cities in the world (The Economist
Intelligence Unit, 10). To maintain its competitiveness, the city has embraced city building policies that
will position Toronto at the forefront of macro energy trends: decarbonisation, decentralisation, and
digitisation. Addressing climate change is a key priority for the city, and its climate change action plan,
titled ‘TransformTO’, envisions ‘a city that has achieved a low-carbon future while enhancing [its] local
economy, reducing inequalities, and improving public health’ (Scioli, 11).

Through TransformTO, the city has committed to reduce greenhouse gas (GHG) emissions by 65 per
cent by 2030 and by 80 per cent by 2050 compared with 1990 levels (Scioli, 16). Since the 60 per cent
of GHG emissions in Toronto is generated by buildings (The Atmospheric Fund, 7), the city has identified
thermal energy networks as a critical strategy to meet its goals (Scioli, 32).

Challenge and response

Beginning in the 1980s, concerns about depleting the atmosphere’s ozone layer became a key issue
for governments around the world, including the City of Toronto. At that time, the primary means
of cooling buildings were chiller systems that used chlorofluorocarbon (CFC) refrigerants, which are
chemicals that are particularly harmful to the ozone layer. Although CFC’s have been phased out by
regulations and replaced by less harmful substances, managing the environmental impacts of common
refrigerants remains a challenge (Environment and Climate Change Canada, 1). While seeking solutions
to reduce CFC’s, a creative mechanical engineer, along with a group of environmentalists and politicians,
developed the original concept for Deep Lake Water Cooling (DLWC), a system that would use cold
water from the depths of Lake Ontario to supply cooling to buildings in the downtown core instead of
refrigerant-driven chillers.

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