35 years of experience in the La Défense business district in Paris

SUC (Société Urbaine de Climatisation) manages a 73.5 MW chilled water production and distribution network on the banks of the Seine.

The network, which cools 50% of the buildings in La Défense, has changed radically since it was commissioned in 1972. The plant, which once produced a huge cloud of steam, is now an invisible part of the business district, hidden beneath a large office block.
The cooling towers were replaced in 1992 by a station pumping water from the Seine. Awareness of environmental issues has prompted profound changes.
In line with new regulations, the CFC-type refrigerant fluids (R500) were replaced by HFCs (R134A), after complete refurbishing of the unit and its surroundings.
As a result of these innovations, in 1999 the company was one of the first in France to obtain ISO 14001 environmental certification.
The 17-strong team responds to the needs of increasingly demanding customers on a daily basis. "Only the tiniest variation in water delivery temperature, contractually set at 4.5°C, is now tolerated," explains Roger Aguilera, SUC's head of operations.
"We must supply cooling to customers whose facilities are their nerve centers. Many banks and insurance companies, for example, have set up their trading rooms in La Défense - and the computers do not tolerate any overheating!" Roger Aguilera and his team must supply the right power at the right time, a skill which comes from many years of experience. "There is consumption peak at 11:30 a.m., when the kitchens begin cooking, and at 4:30 p.m.,when the early leavers let heat in through the swing doors. In winter, too, airconditioning is vital, because when a low sun hits the glass walls horizontally, the temperature inside rises very quickly."

The future promises yet more challenges. In theory, very severe flooding could inundate the pumping station. SUC has anticipated this risk by building a second station, capable of operating underwater. And the renovation plan for La Défense will force the company to double its production capacity by 2015.
The "old lady" still has many happy days ahead.