How to Build a Data Centre Cooling Budget Ian Cathcart Chatsworth Products
Topics We ll Cover Availability objectives Space and Load planning Equipment and design options Using CFD to evaluate options Costing analysis outputs
Availability Objectives Macro redundancy at the data center level Fault-tolerant Maintainable Concurrently maintainable and fault-tolerant
Space Planning Start with what you know: Cabinets Floor tiles Add growth Business objectives Known planned expansions SWAG 7% for 10 yrs = 2X 10% for 7 yrs = 2X Pay attention: 10% annual business growth data center growth Data center growth may be a step function Trends and technology forecasts
Power Planning Start with what you know: UPS readings Power company bills Add growth Business objectives Known planned expansions SWAG 7% for 10 yrs = 2X 10% for 7 yrs = 2X Trends and technology forecasts
Energy Use in Data Centre s ENERGY USE COMPONENT WATTS PER SQ METRE PERCENT Data Centre e Cooling Load (UPS) 100 56% Chiller Load @ 7 C 23 13% Electric Room Cooling Load 14 8% CRAH Fan Power 12 7% Data Centre Cooling Load (lighting & skin) 8 5% Back of House Skin Load 3 2% Chilled Water Pump 3 2% Pump Cooling Load 3 2% Condenser Water Load 2 1% Ventilation Latent Heat Load 2 1% Ventilation Sensible Load 0.7 1% Cooling Tower 07 0.7 1% Chiller Heat Rejection to Ambient 0.3 0% Back of House Lighting 0.3 0% Total 172 100%
Cooling Planning All power becomes heat Sensible Load Latent and external loading 1 ton per 93 square meters (1000 sq feet) Rule of thumb: Cooling energy = ½ UPS energy Final design could be +100% / - 90%
Spaces Requiring Other Cooling Air Data center pressurization air handling unit 8.5 CMH per 9m 2 outside air Use for humidity control N+1 PDU @ 4-5% UPS room Heat (kw) = 10% of UPS kw output CRAC/CRAH @ N+1 Battery room 2 CMH per square metre for Hydrogen exhaust Air handler (N+1) Substation room Transformer heat = 4% of kw output CRAC @ N+1
Determine Sensible Cooling Rack Mounted Drawer Load Configuration Condition Typical Heat Airflow Weight Overall System Dimensions b Release (W x D x H) (Voltage 110 V) Nominal a Maximum at 35 C watts cfm (m 3 /h) cfm (m 3 /h) lbs kg in. mm Minimum 420 26 44 40 68 117 53 25 x 37 x 23 630 x 933 x 584 Full 600 30 51 45 76 117 53 25 x 37 x 23 630 x 933 x 584 Typical 450 26 44 40 68 117 53 25 x 37 x 23 630 x 933 x 584 ASHRAE Class Configuration 3 Description Model Minimum Full Typical 1-way, 1.5 GHz processor, 16 GB memory 2-way, 1.65 GHz processor, maximum memory 1-way, 1.65 GHz processor, 16 GB memory...
Forecast The Life of The Data Centre
Apply Power Trends to Plan How many technology refreshes is the data center being planned to see? Plot refresh growth from point on the trend curves where you are today Determine how much of the forecasted load to include in initial capacity
CRAC/CRAH Selection Cooling capacity requirement (growth + redundancy) Efficiency (EER/SEER or COP) CRAH-1w/EC EER = 58 CRAH-2wEC EER = 133 CRAH-3 centrifugal EER = 43 Close-Coupled EER = 38 CRAC-1 EER = 14 CRAC-2 EER = 11 kw per ton Chiller New Chiller Existing Reciprocating.78 to. 85.90 to 1.2 or higher Screw.62 to.75.75 to.85 or higher Centrifugal High.50 to.62 NA Centrifugal Moderate.63 to.70.70 to.80 or higher CRAC (DX) 1.0 to 2.0 1.5 to 2.5 or higher Free-cooling opportunities
Determine Minimum Number of CRAC Units ete e u u be o C C U ts (Excluding Redundancy)
Add in heat from non-it load heat-producers Note data center chilled water capacity requirement:
Example of facility considerations Significant variation with leaving water temperature
10% Remember: 95 tons for data centre
Supply air based on return air temperature
Hot aisle return air is encroaching on cold aisle
Supply air temperature control with 15.5 C set point
Sample chiller efficiency as a function of leaving chilled water temperature, units of kw/ton 14.5% 5 C 7 C 10 C 13 C 16 C 18 C 21 C Leaving Water Temperature (deg C) Chart from ASHRAE Data Center Design and Operation Book#6: Best Practices for Datacom Facility Energy Efficiency
At 15.5 C (60 F) supply air Deliver 29% excess supply air over actual demand of IT equipment Difference = Bypass
Create VAV functionality by copying standard cooling unit and giving it a reduced airflow rate 95% airflow rate
Cooling Unit Redundancy Planning Non-compliant cooling unit location
5CU s @ 76% capacity 12 hp CU fan motors = 9.1kW.76 3 = 44% max fan energy 4kW per CU or 20kW total 4 CU s running at 100% capacity consume 36.4kW 5 CU s use 175,200 kw hours in a year 4 CU s use 318,864 kw hours in a year
Data center in spec with n+1 CU s running at 76% fan speed
Hot Air Containment Scenario
64% airflow volume Higher supply air temperature t < 1.5% over-supply
All server inlet temperatures are within recommended d environmental envelope
Sample chiller efficiency as a function of leaving chilled water temperature, units of kw/ton 38% 5 C 7 C 10 C 13 C 16 C 18 C 21 C Leaving Water Temperature (deg C) Chart from ASHRAE Data Center Design and Operation Book#6: Best Practices for Datacom Facility Energy Efficiency
5 CU s @ 64% capacity 12 hp CU fan motors = 9.1kW Note air movement to chiller energy ratio.64 3 = 26% max fan energy 2.4kW per CU or 9.6kW total 110 tons chiller capacity @ 380 watts per ton 41.8kW to operate chiller @ 65 F H 2 O leaving temperature
Cooling Cost Roll-up 9.6kW to operate 5 cooling units @ 64% capacity 41.8kW to operate chiller @ 18 C H 2 O leaving temperature 006kWf 0.06 for fresh air (N+1) 0.56kW for electrical room (N+1) 0.06kW for battery room (N+1) 15kW for substation ti (N+1, but not simultaneously l running redundancy 588,000 kw hours per year $58,800 cooling budget at $0.10 per kw hour (1.22 COOLING ONLY PUE)
SUMMARY Real IT load Account for all the invisible heat load sources Forecast intended life of space Calculate variable volume Affinity Law efficiencies for fans and pumps Model test scenarios
QUESTIONS? Ian Cathcart icathcart@chatsworth.com +44 750 800 6018