IBM has launched Cool Blue to reduce heat generated by equipment in the data centre. Branded Cool Blue, the solution works only with IBM's own racks, including those designed for the company's Cluster 1350 architecture. Prices start at US$4,299. Fitting onto the rear door of IBM server racks, the device taps into the chilled water supply circulating in companies' air conditioning systems. A rack with 80 servers can produce about 80,000 BTUs of heat per hour. The US market cost is around 7 cents per kW hour.