Data centre air managementCase studies

Sophia Flucker

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w.d

c-oi

.com

IT • Rationalise• Consolidate• Virtualise

Air Management

• Minimise• Bypass• Recirculation• Negative Pressure

Flow

Mechanical • Increase set points• Reduce fan volume• Optimise humidificationElectrical •Efficient

•UPS•Lights

Mains

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 Mi1200kW 800kW

600kW

Mf

22C

17C

21C

27C

BPBP

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

Reco

mm

ende

dRa

nge

Allo

wed

Ran

ge

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

TS = 15°C

TR = 30°C

TR = 25°C

TS = 20°C

TS = 24°C

TR = 21°C

TR

21°C (69.8°F)30°C (86°F)30°C (86°F)

10% LOAD

TR

Ts

Ts

Air control: return / supply25°C (77°F) 25°C (77°F) 25°C (77°F) 25°C (77°F)

15°C (59°F) 24°C (75.2°F)

20°C (68°F) 20°C (68°F)20°C (68°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 strategiesFixed speed

all runFixed speed one standby

CRAHs with VFDs

8 kW 8 kW 8*(4/5)^3 = 4 kW8 kW 8 kW 8*(4/5)^3 = 4 kW8 kW 8 kW 8*(4/5)^3 = 4 kW8 kW 8 kW 8*(4/5)^3 = 4 kW8 kW Off 8*(4/5)^3 = 4 kW

40 kW 32 kW 20 kW

N

+25%

Chillers CRAH units

Buffer tanks

Primary circuit Secondary circuit

Dry coolers / Cooling towers

Energy optimisation programme1. 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)

Our workshops are accredited by CIBSE

sophiaflucker@dc-oi.comwww.dc-oi.com

www.linkedin.com/company/operational-intelligence-ltd@OI_RobertTozer

Questions?