Air Conditioning and Computer Centre Power Efficiency The Reality Christophe Martel Tony Cass

2 Data Centre Cooling Options Outside Air Cooled Air – Central distribution – Local distribution – Very local distribution Direct Water Cooling

3 Basic Housekeeping is essential! Nice background for a ballerina and a nice way to preheat the inlet air for the servers behind! A much better design.

4 Basic Housekeeping is essential! Mind the gaps!

5 Basic Housekeeping is essential! Hot is cool! But not too hot: Vendors now accept that their systems will run at higher temperatures, but there are reports that server energy efficiency starts to drop above a certain temperature. Indoor conditions from 20°C to 27°C Classical free cooling Outdoor Temperature [°C] Nb of hours / year Extra Free cooling COOLING

6 High density starts at 6KW/rack 0 < low density < 2kW/m 2 < high density Central air cooling < 2kW/m 2 < Local air cooling 30% of the area for racks Basic data Standard air velocity: max 0.25 m/s Temperature in/out IT : 8°C Area equivalence: 1 rack front side = 3.33 floor tiles Typical rack Typical room

7 Reducing air speed False floor. False ceiling for return air. Cold aisle closed. Hot aisle open. Cold aisle closed

8 Reducing air speed No false floor. False ceiling for return air. Cold aisle open. Hot aisle closed. Wall side or peripheral air distribution

9 How do you make cold air? Via heat exchange with something else which rejects heat to the environment – something else is usually water Heat wheel is one alternative – But closer in spirit to complete fresh air cooling: supplemental cold air generation will be required if peak temperatures approach the desired set point for machine room temperature.

10 How do you make cold water? Air cooled chillers dry coolers Towers COOLING PRODUCTION COOLING DISTRIBUTION Pipes Pumps Pipes Pumps Screw or Compressor type Absorption type Water cooled chillers Water cooled rack Air handling units Horizontal / vertical In row cooling

11 Optimising Chilled Water Generation Fans, pipes: size optimisation -> pressure drop of the system Fan/pump motors: – Preferably variable speed drive (30%); if not then Eff1 class(10%) High efficiency exchangers Filter selection and period maintenance Regulation optimisation via significant indicators And, most importantly, the chillers…

12 Annual Electricity Consumption Efficient Data Centre — PUE=1.3

13 Take time for chiller selection Eurovent Certification certifies the performance ratings of air-conditioning and refrigeration products according to European and international standards. Energy efficiency Ratio (EER) Ratio of the cooling capacity to the power input of the unit. European Seasonal Energy efficiency Ratio (ESEER) ESEER = A.EER100% + B.EER75% + C.EER50% + D.EER25% Recent Chiller Optimisations Free cooling option for air cooled chiller Oversizing with variable speed drives (EER up to 10!) Adiabatic coolers Smartcools systems EER between 3.16 to 3.63 (delta 15%) ESEER between 3.86 to 4.31 (delta 20%)

14 Chiller size selection Data centers are easy to design compare to other buildings! Cooling Power [kW] Time [Days] Classical Cooling Power demand Cooling power installed +30% Typical buildingData Centre Cooling power installed +15% Chiller 1 Chiller 2 Chiller 3

15 Conclusion Optimise everywhere!