Utilization of Computer Room Cooling Infrastructure: Measurement Reveals Opportunity (OPEX, CAPEX, Density) LARS STRONG, P.E.
Utilization of Computer Room Cooling Infrastructure: Measurement Reveals Opportunity (OPEX, CAPEX, Density)
Jun 29, 2015
Study of data centers reveals the average computer room has cooling capacity that is nearly four times the IT heat load. When running cooling capacity is excessively over-implemented, then potentially large operating cost reductions are possible by turning off cooling units and/or reducing fan speeds for units with variable frequency drives (VFD). Using data from 45 sites reviewed by Upsite Technologies, this presentation will show how you can calculate, benchmark, interpret, and benefit from a simple and practical metric called the Cooling Capacity Factor (CCF). Calculating the CCF is the quickest and easiest way to determine cooling infrastructure utilization and potential gains to be realized by AFM improvements.
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Utilization of Computer Room Cooling Infrastructure: Measurement Reveals Opportunity (OPEX, CAPEX, Density)
LARS STRONG, P.E.
Agenda
The State of Computer Room Airflow Management Understanding Your Cooling Utilization with the Cooling
Capacity Factor Research & Case Studies
The State of Airflow Management
2002 Uptime Institute Research
Bypass Airflow* 60%
Hot Spots 10%
Cooling Capacity 2.6x
2012 Upsite Technologies Research
Bypass Airflow* 48%
Hot Spots 20%
Cooling Capacity 3.9x
*More accurately, “Raised Floor Bypass Open Area” in today’s terminology.
But Why?
Cooling capacity is difficult to quantify It’s hard to justify initiatives, determine ROI Conflict of interest,
vendor influence No ‘one-size-fits-all’ solution People paying the electric bill
detached from the data center Few organizations have objectives clearly stated that can
be supported by cooling optimization
Bypass Airflow Clarified
Typical existing conditions
Bypass Airflow Clarified
After AFM improvements
Bypass Airflow Clarified
Optimized
High Awareness, Low Implementation
• Open holes in the floor
• Blanking panels often missing
• Misplaced perforated tiles
• Gaps between racks
AFM Problems Are An Opportunity•Money
•OpEx Savings•CapEx Savings
•Capacity•Cooling Capacity•Room for IT Equipment
•IT Reliability
•Green Initiatives•CO2 Reduction
“…an average data center could reduce its operating expense by $32,000 annually, simply by improving airflow management.” - Upsite CCF White Paper
The Cooling Capacity Factor (CCF) A metric Upsite Technologies developed to
determine the cooling effectiveness of a data center. CCF measures the cooling output relative to the IT load, providing an accurate picture of cooling infrastructure efficiency.
CCF: How It’s Calculated
Convert the total rated (stated) cooling capacity to kW, divide by 110% of the IT critical load (kW)
Total rated cooling capacity (210 tons x 3.52) = 739 kW
110% of the IT critical load = 259 kW
CCF = 2.8 (739/259)
Rated capacity is 280% of the load
The Research
Raised floor area
(sq ft)
# of running cooling units
Raised floor
bypass open
area (%)
Hot spots (%
of cabinets
)
Cold spots (%
of cabinets) (Data from 6 sites)
Proper perforated tile
placement (%)
Cooling Capacity Factor (CCF)
Averages 7,527 8 48% 20% 35% 77% 3.9Minimum 720 2 13% 0% 0% 7% 1.2Maximum 37,00
040 93% 86% 86% 100% 32.0
Recommended
n/a n/a <10% 0% 0% 100% 1.2Conclusion: Inefficient cooling configuration / airflow management is the problem; capacity is not the problem.
Case Studies
#1 - Large Financial Cooling unit capacity 65kW Total number of cooling units running 34 Total rated cooling capacity 2,210 kW (34 x 65 = 2,210 kW) UPS output load 642kW Estimated heat load 706 kW (642 kw x 1.1 = 706 kW) CCF 3.1 (2,210 / 706 = 3.1)
Case Studies#1 - Large Financial 34 cooling units running 11 units at full capacity required to support load Conservatively adding 5 for redundancy 16 needed 18 cooling units could be turned off (34 – 16 = 18) 18 units, 7.5hp fan motors = 122kW reduction At $0.10/kWhr, = $8,901/mo, $106,813/yr savings At $2,000/unit/yr maintenance $36,000/yr savings Total savings $142,000/yr
Case Studies#2 – small (2,000 sqft) hardware manufacturer
Before conditions Total rated cooling capacity 645 kW Estimated heat load 300 kW CCF 2.2 (645 / 300 = 2.2)
After conditions Total rated cooling capacity 560 kW (after turning 2 off) Estimated heat load 310 kW CCF 1.8 (560 / 310 = 1.8) Reported annual savings $21,000 8 month ROI on air flow management improvements
RememberTons x 3.517 = kWc
Cooling unit capacity Rated capacity at standard conditions (75 deg F, 45%Rh) Capacity goes up with increase in return temperature Capacity goes down with decrease in return temperature ASHRAE Guidelines
•Temperature range: 64°F to 80.6°F (18°C to 27°C)•Dew Point range: 42°F to 60°F (5.5°C to 15°C)
Important Metrics
PUE CCF Bypass open area Hot Spots - % of cabinets containing a hot spot Cold Spots - % of cabinets containing a cold spot Perforated tile placement - % of perforated tiles properly placed Ratio of supply air volume to IT equipment airflow volume
Questions?Lars Strong, P.E.
Senior Engineer, Upsite Technologies
Follow Upsite for the latest news and information on data center AFM.
@UpsiteTech
blog.upsite.com
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