The Economics of Data Center
Air Flow Containment
Course Description
This course will explain:
1. The acceptable range of equipment inlet conditions
2. The value of supply air set points versus return air set points
3. The value for maximizing the separation between supply air streams and
return air streams.
4. The benefits for maintaining air separation including:
•
•
•
•
•
•
•
•
elimination of equipment hot spots
elimination of bypass and re-circulation waste
reduction in fan energy
improvements in cooling coil efficiency
ability to support trends toward higher rack heat density
improvement in chiller plant efficiency
access to increased hours of economization cooling
increased overall design flexibility
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Learning Objectives
At the end of this program, you will be able to:
1. Discuss the three basic methods for achieving air separation through hot
aisle containment, cold aisle containment, and vertical exhaust ducts.
2. State the relative advantages and disadvantages for the different separation
topologies along with application appropriateness.
3. Quantify the cost-benefits for a well-designed air flow management.
4. Explain the overall value of good air flow management, and how
it can be achieved using design elements that can enable or
compromise best results.
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What is the source of your pain?
• Hot spots?
• Cost for energy?
• Growth and/or technology refresh constrained?
• High cost of eliminating hot spots or reducing energy
costs or positioning for growth?
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Uptime Institute
2012 Data Center Survey
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Limitations of Hot Aisle – Cold Aisle
HOT
AISLE
COLD
AISLE
HOT
AISLE
COLD
AISLE
• Hot air recirculation from the hot aisle into the cold aisle
• Bypass airflow under the cabinets
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What is the target?
The New ASHRAE
Recommended Environmental Envelope
for Class 1 Electronics
Low End
Temperature
High End
Temperature
Low End Moisture
High End Moisture
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2004 Version
2008 Version
20°C (68°F)
18°C (64.4°F)
25°C (77°F)
27°C (80.6°F)
40% RH
5.5°C DP (41.9°F)
60% RH & 15°C DP
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(59°F
DP)
55% RH
Typical Set Point Management
72°F (22°C)
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Typical Set Point Management
Mixing of supply air
and return air in
typical data center
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Typical Set Point Management
72°F (22°C)
• Hot spots
Return air could
cool an
An• Employee-Owned
Corporation
entire data center
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Supply Set Point Management
All the hot return air is isolated
from the supply air
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• No hot spots.
• No concern about return air
temperature.
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What is Hot Air Isolation
-Completely preventing hot and cold air from mixing
-Completely capturing either hot or cold air
-100% is probably unrealistic
-leakage is important
-many design trade-offs
-Several design strategies
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Benefits of Hot Air Isolation
1. Eliminates hot spots
2. Supports 4x higher heat and power densities (6 kW to 30+kW)!
3. Effectively utilizes 100% of supplied air and reduces chilled air waste!
4. Transfers server equipment ΔT directly back to the HVAC unit!
5. Increase chiller efficiency through higher set points!
6. Can increase economization through higher set-points!
7. Allows supply air delivery from ceiling, wall or floor.
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Elimination of Hot Spots
86
83
81
78
75
72
70
67
64
62
59
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Benefits of Hot Air Isolation
1. Eliminates hot spots
2. Supports 4x higher heat and power densities (6 kW to 30+kW)!
3. Effectively utilizes 100% of supplied air and reduces chilled air waste!
4. Transfers server equipment ΔT directly back to the HVAC unit!
5. Increase chiller efficiency through higher set points!
6. Can increase economization through higher set-points!
7. Allows supply air delivery from ceiling, wall or floor.
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High Density Cooling
4 IBM H 8852 Blade Servers
25kW actual heat load
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4 HP c7000 Blade Servers
22kW actual heat load
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Benefits of Hot Air Isolation
1. Eliminates hot spots
2. Supports 4x higher heat and power densities (6 kW to 30+kW)!
3. Effectively utilizes 100% of supplied air and reduces chilled air waste!
4. Transfers server equipment ΔT directly back to the HVAC unit!
5. Increase chiller efficiency through higher set points!
6. Can increase economization through higher set-points!
7. Allows supply air delivery from ceiling, wall or floor.
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Elimination of Excess Supply Air
600kW IT load
6 Stulz CCD-1800-CWE CRAH units (N+1)
Standard Hot Aisle – Cold Aisle Data Center
• Air handlers operate @ 83% capacity
• Maximum inlet temperature range = 58.6°F – 79.7°F
• CRAH fan energy = 32.1 kW or 280,937 kW hours/year
Data Center with Hot and Cold Isolation
• Air handlers operate at 73% capacity
• Maximum inlet temperature range = 75°F – 76°F
• CRAH fan energy = 21.6kW or 189,216 kW hours/year
91,721 kW hours energy saved by eliminating need to
produce excess bypass supply air
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Benefits of Hot Air Isolation
1. Eliminates hot spots
2. Supports 4x higher heat and power densities (6 kW to 30+kW)!
3. Effectively utilizes 100% of supplied air and reduces chilled air waste!
4. Transfers server equipment ΔT directly back to the HVAC unit!
5. Increase chiller efficiency through higher set points!
6. Can increase economization through higher set-points!
7. Allows supply air delivery from ceiling, wall or floor.
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CRAC Efficiency with Supply/Return Isolation
Cooling Unit
Supply Air
Temperature
Stulz CCD-600-CWE
Labeled as
10 Tons
Return Air
Temperature
Cooling
Capacity
70˚ F
7.8 tons
90˚ F
15.5 tons
105˚ F
20.7 tons
70˚ F
23.0 tons
90˚ F
46.0 tons
105˚ F
61.3 tons
60˚ F
Stulz CCD-1800CWE
Labeled as
30 Tons
Almost a 3x improvement in cooling unit efficiency!
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Benefits of Hot Air Isolation
1. Eliminates hot spots
2. Supports 4x higher heat and power densities (6 kW to 30+kW)!
3. Effectively utilizes 100% of supplied air and reduces chilled air waste!
4. Transfers server equipment ΔT directly back to the HVAC unit!
5. Increase chiller efficiency through higher set points!
6. Can increase economization through higher set-points!
7. Allows supply air delivery from ceiling, wall or floor.
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Chiller Efficiency at Higher Set Points
38%
Energy
Savings
38% savings = $168,521
1MW example
Chart from ASHRAE Data Center Design and Operation Book#6: Best Practices for Datacom
Facility Energy Efficiency
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Benefits of Hot Air Isolation
1. Eliminates hot spots
2. Supports 4x higher heat and power densities (6 kW to 30+kW)!
3. Effectively utilizes 100% of supplied air and reduces chilled air waste!
4. Transfers server equipment ΔT directly back to the HVAC unit!
5. Increase chiller efficiency through higher set points!
6. Can increase economization through higher set-points!
7. Allows supply air delivery from ceiling, wall or floor.
An Employee-Owned Corporation
800-834-4969 | www.chatsworth.com
Increase Economization Through Better
Separation Between Supply and Return Air
538.5kW
Load
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Increase Economization Through Better
Separation Between Supply and Return Air
538.5kW
Load
An Employee-Owned Corporation
800-834-4969 | www.chatsworth.com
Increase Economization Through Better
Separation Between Supply and Return Air
538.5kW
Load
An Employee-Owned Corporation
800-834-4969 | www.chatsworth.com
Benefits of Hot Air Isolation
1. Eliminates hot spots
2. Supports 4x higher heat and power densities (6 kW to 30+kW)!
3. Effectively utilizes 100% of supplied air and reduces chilled air waste!
4. Transfers server equipment ΔT directly back to the HVAC unit!
5. Increase chiller efficiency through higher set points!
6. Can increase economization through higher set-points!
7. Allows supply air delivery from ceiling, wall or floor.
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Design Flexibility
Return
Supply
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Strategies for Air Isolation
Hot Aisle
Containment
(HAC)
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Cold Aisle
Containment
(CAC
Hot air isolation
(chimney or VED)
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Containment Starts Inside the Cabinet
Floor Tile Cut-out Grommets
Cabinet Air Dams
Blanking Panels
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Cabinet Air Re-Circulation
CFD Model
Thermal Imaging Photograph
1” rail set-back = 5+ RMU open space between hot area and cold area
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Cold Aisle Containment
538.5kW
Load
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Hot Aisle Containment
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Hot Air Isolation
with Cabinet Vertical Exhaust Duct
538.5kW
Load
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Hybrid Containment with Chimney
Cabinets and Hot Aisle Containment
538.5kW
Load
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What Is the Best Containment?
DataCenter 2020: Hot-aisle and Cold Aisle Containment
Efficiencies Reveal No Significant Differences
Copyright © 2011 Intel Corporation.
The DataCenter 2020 is a joint T-Systems and Intel data center test
laboratory in the Munich-based Euroindustriepark.
www.datacenter2020.com
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Hot Aisle Containment
Easy integration of fire suppression
Hot aisle working environment @ 90 – 130⁰F
Flexible supply air delivery architectures
Better low density thermal ride-through
Raised floor not required
Pod deployment
Compatible with row-based cooling
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Cold Aisle Containment
Data Center working environment @ 90 - 130⁰F
Better high density thermal ride-through
Easier retrofit of working data center
Raised floor (usually)
Separate “volume” for fire suppression
Pod deployment
Possibly sensitive to over-pressure
Compatible with row-based cooling
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Cabinet Containment
Working environment @ 74 - 80⁰F
16’ pitch may impact fire suppression
Raised floor not required
Thermal ride-through (variable dependent)
Cabinet deployment
3050 CFM density threshold
Flexible supply air delivery architectures
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Case Study
• 300kW IT load
• 2000 square feet
• 150 watts per square foot
• 60 cabinets
• 1,025,567 BTU/hr
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Cooling Cost Roll-up
12kW to operate 5 cooling units @ 64% capacity
41.8kW to operate chiller @ 65°F H2O leaving temperature
0.06 kW for fresh air (N+1)
0.56kW for electrical room (N+1)
0.06kW for battery room (N+1)
15kW for substation (N+1, but not simultaneously running redundancy
608,119 kW hours per year
$60,812 cooling budget at $0.10 per kW hour
(1.23 COOLING ONLY PUE)
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Savings Comparison
• 44% cooling energy savings over original data center
– 35.8% reduction in chiller plant energy
– 73.7% reduction in CRAH fan energy
• 30% cooling energy savings over optimized hot aisle – cold
aisle data center
– 30.8% reduction in chiller plant energy
– 52% reduction in CRAH fan energy
• No economizer in any scenario
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Benefits of Airflow Management
by Containment
• Eliminates hot spots
• Suitable for low, medium and high density
• Eliminates wasted capacity and saves fan energy
• Improves cooling unit efficiency
• Supports supply air set points
– Reduced chiller plant energy use
– Increased “free cooling” utilization
• Facilitates greater design and deployment flexibility
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Thank You For Your Time
Questions?
This concludes The American Institute of Architects
Continuing Education Systems Course
Glen ter Horst
(708) 990-0798
gterhorst@chatsworth.com
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