When constructed in 2008, the Cool Circle represented a unique project in Europe. We still use the Cool Circle to cool many buildings and research equipment on campus today. Several smart solutions, combined into one system, make for a very sustainable approach to cold storage at UT.
The Cool circle is used to cool many buildings and research equipment on campus. Often, heat/cold storage takes place in the ground, but this is not possible on the UT site due to the geomorphology of the soil. It was therefore decided to take an unconventional approach. The Cool Circle is a 10 meters deep and 35 meters wide large reservoir that stores over 10 million liters of cold water.
At night, the water in the pond is cooled: in summer with cooling machines, in winter using the outside air. The cool night combined with the cooling units cool the water to about 8 to 10 degrees Celsius. Through a loop system, the water is distributed through the buildings. The cooler water flows in at the bottom of the reservoir, while water of about 18 degrees that has been used to cool buildings flows in at the top. This creates a temperature gradient, with the top layer insulating the cooler water: a so-called ‘thermocline’.
The boundary between cold and hot water changes during the day, the buffer capacity changes depending on the use of the cooling system, but cold and hot will never mix. This makes for a very efficient system.
The Cool Circle has a cooling capacity of 11 MegaWatts, which is equivalent to the capacity of over 70,000 refrigerators. The cold circle also acts as a water storage buffer in the event of a major fire. Currently, the Horst complex, Carré, Nanolab, Ravelijn, Hall B, Zilverling, Citadel, Langezijds, Technohal en Cube, High Pressure Lab, Seinhuis and Teehuis are all connected to the Cool Circle.
