District Cooling,
Chicago-Style:
World’s largest interconnected system continues to grow
River North areas. Thanks to its proven reliability and multiple
benefits, customers have turned to Thermal Chicago’s district
cooling service as an alternative for both new and replacement
air-conditioning systems. Its mixed customer base includes
commercial facilities, office towers, condominiums, apartment
buildings, theaters, hotels, data centers, retail centers and
schools. Its contract capacity has increased approximately
15 percent since 2004 – and it’s still growing.
System History
Chicago’s district cooling system has a brief but intriguing history. Its origins can be traced back to a landmark international agreement designed to reverse the thinning of the
stratospheric ozone layer that shields the planet from UV-B
radiation. The Montreal Protocol on Substances that Deplete
the Ozone Layer was negotiated and signed by 24 countries
and the European Economic Community in September 1987.
The Protocol called for the phase-out of ozone-depleting
chemicals including chlorofluorocarbons (CFCs), commonly
used as refrigerants in air-conditioning systems. Many of
Chicago’s commercial buildings were operating chillers that
used such refrigerants and were thus faced with the expensive
prospect of either replacing or refurbishing them. Chicago’s
electric utility, Commonwealth Edison Co. (ComEd), convinced
customers to contract their cooling service from a new district
cooling system that could operate without CFCs.
During the early 1990s, it was not uncommon for regulated utilities like ComEd (now a subsidiary of Exelon Corp.)
to branch out into nonregulated utilities such as thermal
energy systems. ComEd saw such an opportunity in downtown Chicago and built a district cooling plant in the heart
of the Loop. By 1995 the system had about a dozen customers, primarily older buildings whose chillers would have soon
required replacement. Over time, the customer base expanded
