Chillers in a district cooling district cooling system pdf University of Rochester in Rochester, New York. District cooling is the cooling equivalent of district heating. Working on broadly similar principles to district heating, district cooling delivers chilled water to buildings like offices and factories needing cooling.
In winter, the source for the cooling can often be sea water, so it is a cheaper resource than using electricity to run compressors for cooling. Alternatively, District Cooling can be provided by a Heat Sharing Network which enables each building on the circuit to use a heat pump to reject heat to an ambient ground temperature circuit. The Helsinki district cooling system uses otherwise wasted heat from summer time CHP power generation units to run absorption refrigerators for cooling during summer time, greatly reducing electricity usage. In winter time, cooling is achieved more directly using sea water.
The adoption of district cooling is estimated to reduce the consumption of electricity for cooling purposes by as much as 90 per cent and an exponential growth in usage is forecast. The idea is now being adopted in other Finnish cities. The use of district cooling grows also rapidly in Sweden in a similar way.
Cornell University’s Lake Source Cooling System uses Cayuga Lake as a heat sink to operate the central chilled water system for its campus and to also provide cooling to the Ithaca City School District. Working since 1985, the system of the École Polytechnique Fédérale de Lausanne combines, depending on the needs, cooling and heat extraction. This allows for a higher overall energy efficiency of the 19 MW system.
In 2009, a district cooling system was installed in the United Nations area of Geneva, drawing water from Lake Geneva. The system is in the process of being expanded to other areas of Geneva.
In August 2004, Enwave Energy Corporation, a district energy company based in Toronto, Ontario, Canada, started operating a system that uses water from Lake Ontario to cool downtown buildings, including office towers, the Metro Toronto Convention Centre, a small brewery and a telecommunications centre. Another feature of the Enwave system is that it is integrated with Toronto’s drinking water supply. The Toronto drinking water supply required a new intake location that would be further from shore and deeper in the lake.
This posed two problems for the utility that managed the city’s drinking water supply: 1. The cooperation of the district cooling agency, Enwave, solved both problems: Enwave paid for the cost of moving the water intake and also supplied the heat to warm the drinking water supply to acceptable levels by effectively extracting the heat from the buildings it served.