One important mechanism for reducing Data Centre operating costs is reducing energy consumption. The energy consumed by customer equipment is largely beyond our control, but the energy used to cool customer equipment can be managed by good operational control and by the employment of tactical measures that reduce consumption without impact on service delivery.

1. Air handling plant used to pressurise the data hall space, service the office/general circulation areas and cool the switchroom/plantroom areas maximises the use of outside air. The UPS rooms use only fresh air as the cooling medium; thus cooling energy usage is limited to the fan power only.
    
2. Warm chilled water returning from data hall areas can be diverted over ‘dry air coolers’ before being returned to the centralised chiller plant. By this mechanism ‘free cooling’ can be employed when external air temperatures fall below 14 deg C. At maximum output, the free cooling installation can deliver thousands of kW of cooling thereby limiting energy use to  fan and small pump power only, presenting substantial annual electrical energy savings .There is a dependency on the close attention of the Operations Team in order that control set points for data hall temperature and chilled water flow and return temperatures are set and maintained at the optimum level to secure maximum benefit. The ‘chilled water free cooling’ system is a non-critical function, side-stream to the critical centralised chiller plant, i.e. failure of the system does not compromise the Data Centre operations. It does, however, add the benefit of improving redundancy during ‘cool’ months in that it creates more flexibility for critical systems maintenance.