Data centre air management Case studies Sophia Flucker

IT Rationalise Consolidate Virtualise Air Management Minimise Bypass Recirculation Negative Pressure Flow Mechanical Increase set points Reduce fan volume Optimise humidification Electrical Efficient UPS Lights Mains Renewable sources

NP (Negative Pressure flow): data hall air drawn into raised floor due to high under floor velocities (Venturi effect). Avoid high air velocities under floor grilles BP (ByPass) flow: cooled air that returns to CRAH without cooling IT eq. Avoid floor grilles in hot aisles and close cable cut- outs in back of racks R (Recirculation) flow: discharge from IT equipment that is drawn back into IT eq inlet. Install rack blanking plates and ensure sufficient air is supplied to IT equipment Good “hot spot” Bad “hot spot” Air performance: inefficiencies

How much cooling is delivered? Tci Tco Tii Tio Mc Mi 1200kW 800kW 600kW Mf 22C 17C 21C 27C BP R R

Air containment

Air segregation

Containment is only part of the solution

No. of servers 32°C 15°C 27°C 18°C More efficient, more reliableIncrease set pointsWith air management Inlet air temperatures to IT equipment Recommended Range Allowed Range

15°C (59°F) 24°C (75.2°F) 100% LOAD 25°C 15°C 20°C 30°C 25°C 15°C 20°C 30°C T S = 15°C T R = 30°C T R = 25°C T S = 20°C T S = 24°C T R = 21°C TRTR 21°C (69.8°F) 30°C (86°F) 10% LOAD TRTR Ts Air control: return / supply 25°C (77°F) 15°C (59°F) 24°C (75.2°F) 20°C (68°F) 21°C (69.8°F)

Fan speed, flow rate and power Fan Application Guide CIBSE TM42: 2006

Energy savings with different fan strategies Fixed speed all run Fixed speed one standby CRAHs with VFDs 8 kW 8*(4/5)^3= 4 kW 8 kW 8*(4/5)^3= 4 kW 8 kW 8*(4/5)^3= 4 kW 8 kW 8*(4/5)^3= 4 kW 8 kWOff8*(4/5)^3= 4 kW 40 kW32 kW20 kW N +25%

Chillers CRAH units Buffer tanks Primary circuitSecondary circuit Dry coolers / Cooling towers

Energy optimisation programme 1.Energy assessment and data hall air temperature survey to benchmark performance and identify opportunities for improvement. 2.Implementation of air management improvements including installation of cold aisle semi-containment. 3.Modification of CRAH units to reduce fan speeds and control on supply air. 4.Increase in data hall air set points from 24C return to 23C supply and chilled water set points from 6/12 to 17.9/23.9 over several months. 5.Feasibility study on installation of free cooling circuits on existing chilled water systems. 6.Installation of free cooling modification using dry coolers, allowing compressor-free operation for an estimated 63% hours per year. PUE reduction 2.3 to 1.49, annual energy saving $1.3m (1800kW IT load)

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