reducing energy consumption with passive … energy consumption with passive cooling fernando reyna...
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Energy Trends: Gartner Group – Sept. 2007
Traditional data centers have been built to specific design specifications, which
struggle to house current (and future) generation high-density servers.
User switch to new technology results in an
initial sharp drop in energy consumption.
Typical users energy consumption curve of
infrastructure.
Underlying energy consumption curve of infrastructure.
Technology platform requires a sharp
increase in energy driven by volume.
2006 2012 2018
En
erg
Co
nsu
mp
tio
n
in D
ata
Cen
ters
Energy Facts
• Data center energy consumption as a percentage of total United States electricity use has doubled since 2000, and data centers and servers will double their energy consumption again – to 100 billion kilowatt-hours by 2012 (EPA)
• Gartner predicts energy costs could soon consume as much as half of an organization's IT budget, moreover, Gartner estimates that 60 percent of a data center's energy consumption is wasted.
• “It is our No. 1 expense. I pay more for electricity than I do for rent,” said Wayne Sawchuk, CEO and co-founder of ColoSpace, which provides co-location services in six data centers composed of more than 4,000 servers across 35,000 square feet in Massachusetts and New Hampshire.
Energy and Inefficiency
• By 2010, for every $1 spent on hardware, 70 cents will be spent on power and cooling
• By 2012, for every $1 spent on hardware, $1 will be spent on power and cooling
• 46% of data center managers don't know how much they spend on power and cooling
Source: IDC Report
What contributes to the heat load that must be factored in to estimate the
total AC requirement ?
EYP Missions Critical Facilities Inc., New York
Sources of Data Center Energy Consumption
Data Center Energy Realities
• Servers do not require 50º to 55ºF supply air.
• Data Centers are “sub-cooled” to compensate for infrastructure shortfalls.
• A properly designed Data Center requires far less cooling tonnage, and air volume–saving equipment, energy and operational expenses.
Data Center Cooling
• Generation – CRAC’s, or Central Station
• Distribution - Remove obstructions
• Consumption – Use only what you need
• Evacuation – Isolate exhaust air
• Recirculation – Return air directly to A/C unit
– EFFICIENT Design of D, C, E and R dramatically effects G and
associated $$$$$’s.
1. Protect and Deliver Supply Air
2. Minimize Bypass
3. Reduce Recirculation
COLD
AISLE
HOT
AISLE
Cabinet
Cable Tray, Electrical, etc…
Data Center Layout +Supply, Utilization, and Return
Chiller
Loop
Basic Hot Aisle – Cold Aisle Layout
CRAC
CRAC
50 °F
Supply
Air
COLD
AISLE
HOT
AISLE
80 °F Return Air
Vented Floor Tiles
Cabinet Cabinet Cabinet
HOT
AISLE
COLD
AISLE
HOT
AISLE
COLD
AISLE
• Data cable tray should run down hot aisle and be ¾” from bottom of floor tile
• Power cables and conduit should be below and in the cold aisle
Underground Cable Pathway Option
Limitations of Hot Aisle – Cold Aisle
HOT
AISLE
COLD
AISLE
HOT
AISLE
COLD
AISLE
• Bypass airflow under the cabinets
• Hot Air recirculation from the hot aisle into the cold aisle
Poor Data Center Cooling
Insufficient Cold Air Delivered Through Raised Floor
Recirculation and Mixing of Source Air and Return Air
Pre-cools Return Air Temperature
Forces Cooling Units to Operate at Lower Efficiencies
Retains a Lower Chilled Water Temperature
Reduces the opportunity for Economization
Place cooling units at the ends of hot
aisles 8 feet from perforated tiles.
Hot Aisle
C
R
A
C
C
R
A
C
8 Ft Min
Cold Aisle
Cold Aisle
Too Close!
Cooling Unit Placement
Supply Air Distribution Patterns
HIGHEST
FLOW RATE AND PRESSURE INCREASE FARTHER AWAY FROM CRAC
CRAC CRAC
FASTER SLOWER
VELOCITY
SLOWER FASTER
VELOCITY
GREATEST
AREA OF
UNIFORMITY
IS MIDWAY
BETWEEN
CRAC UNITS LESS
UNIFORMITY
LESS
UNIFORMITY
How can you instantly increase your data
center cooling capacity up to 40%
1. Seal all unnecessary access floor openings
– around perimeter walls
– behind cooling units
– behind cabinets
2. Seal all sleeves and wall penetrations.
3. Use vented tiles on only in cold aisles.
By reclaiming wasted bypass air!
Bypass Air Flow
Have at least 64% Open Perforation front and rear metal
cabinet doors to allow sufficient air flow.
Reducing Recirculation Perforated Doors
Use Blanking Filler Panels and Air Dams to seal
between, and around equipment.
Server
BAD
Server
GOOD
Cabinet
without
blanking
panels
and air
dams.
Reducing Recirculation: Filler Panels and Air Dams
• Hot air re-circulates around the
sides and top of the cabinets
• Hot air mixes with cold air
increasing the server inlet air
temperature.
• Blanking panels by themselves
are not sufficient.
Cabinet Air Re-Circulation
The Problems with Cabinet Fans
• Can’t keep up with airflow requirements
of higher density blade servers.
• Will not evacuate hot air out of the
cabinet
• Inhibits hot air from escaping the cabinet
• Adds back pressure to server fans and
slows them down
Air movement capacities of typical cabinet door fans VS.
Air movement requirements of a cabinet full of IBM or Dell Blade Servers
CFM Fan Capacity
400 – 500 Typical Cabinet Top Mount Fan
1350 Highest Standard Top Mount Fan on Market
900 - 1000 Typical Rear Fan
CFM Blade Server Air Movement Requirements
1820 4 IBM eServer Blade Centers
2400 6 Dell PowerEdge 1955
Effect of Fans
Why is it Simply Efficient™?
Because it IS very simple and 100% efficient!
Passive Cooling®
It’s Passive Cooling – No moving parts!
Simply utilizes the Laws of Thermodynamics! - Bernoulli Principle - Venturi Effect - Vena Contracta - Sensible Cooling - Thermal Isolation of Supply and Return Systems
Nothing to “back up” when scaling up Tiers !
No single Points of Failure
Nothing to “pipe to”
No Power Requirement
No Heat Generation
It’s Green!
Passive Cooling
Old Paradigm - The cabinet is a box for housing IT equipment.
Take airflow management
beyond current best
practices and open the door
to numerous other benefits
air containment.
Changing the Cabinet Paradigm
New Paradigm – The cabinet is an integral part of the Data Center architecture as an extension of the cooling system.
Why? Because the cabinet is the architectural feature in the data center that secures the isolation between supply air and return air.
1. Completely isolate cold supply air from hot return air!
2. Ensure that all chilled supply air passes through the server!
3. Maintain a constant temperature data center of 77°F!
5. Maximize economization potential !
4. Significantly reduce mechanical costs for power and cooling!
Using Passive Cooling, you can…
6. Earn up to 8 LEEDS Points !
Passive Cooling – Simply Efficient!
Isolate Cabinet Return Air
High Densities 0 – 30kW per Cabinet
Changing the Cabinet Paradigm
Passive Cooling:
• Supports extreme heat loads – 30 kW and above
• Transfers equipment ΔT to the CRAC/CRAH
• Contains and prevents hot exhaust air from re-
circulating over or around cabinet and entering front of
equipment
• Allows room to be flooded with cold air delivering
uniform cold intake air temperatures to all equipment
• Allows CRAC/CRAH the be 100% efficient!
5. “Vena Contracta Effect” in which air flow through the
constriction increases in velocity and creates another low
pressure area that draws the hot air out of the cabinet!
It’s the Bernoulli Principle!
What makes it work?
3. Low pressure area forms along back side of cabinet.
and pulls hot exhaust air from the other servers into the
stream.
2. Exhaust air from bottom server is turned and
increases in velocity as it rises.
4. Virtual constriction formed in exhaust duct.
1. Chilled air is pulled into the server.
Mechanics of Passive Cooling
H
L
Ducts remove hot air
from the cabinet and
room.
Installing air
segregation
accessories helps.
Air re-circulates
inside the cabinet
and into the room.
TYPICAL BETTER BEST
The Problem with Typical Cabinets
The Vertical Exhaust Duct
• Isolates hot air from the room
eliminating hot air recirculation over
cabinets (between hot and cold
aisles)
• Attaches to the top of 48” deep
cabinets at the rear of the cabinet
• Guides hot exhaust air from the back
of the cabinet to the space above a
drop ceiling or to a hot air return duct.
• Eliminates the need for fans
• Prevent hot and cold air from
mixing within the cabinet
• Closes and seals open rack-
mount spaces
Snap-In Filler Panels and Air Dams Snap-In Blanking Panels
• Attaches to cabinet frame
• Creates an air flow barrier between the
door and equipment along the top, bottom
and sides of cabinet
• Prevents hot and cold air from mixing
within the cabinet
• Creates higher supply-to-return temperature differences (ΔT’s).
• Increases CRAC cooling capacity 2X to 3X allowing use for higher equipment densities and energy cost savings.
• Equalizes room temperature creating a constant temperature situation.
• Equipment intake temps are the same from top to bottom across the cabinet.
• Allows increased room temperature and higher set-points on cooling equipment and chilled water temperatures, for more free cooling hours using low-cost economizers.
Isolation Benefits
Hot Spots
Inconsistent
Temperatures
115
109
103
97
91
85
79
73
67
61
55
Cabinets 2.5 to 3kW per cabinet
Cabinets 2.5 to 3kW per cabinet
Cabinets 2.5 to 3kW per cabinet
Cabinets 20kW per cabinet
Floor Tiles
Floor Tiles
Floor Tiles
°F Traditional Hot Aisle – Cold Aisle Layout in a
Mixed Environment of HD and LD cabinets.
Supports 4X Higher Heat and Power Densities
No Hot Spots
Ideal
consistent
temperature is
created with
PASSIVE
COOLING
solution!
100
95
91
86
82
77
72
68
63
59
54
Cabinets 2.5 to 3kW per cabinet
Cabinets 2.5 to 3kW per cabinet
Cabinets 2.5 to 3kW per cabinet
Cabinets 20kW per cabinet
Floor Tiles
Floor Tiles
Floor Tiles
Installed Ducted Cabinets
°F
Ceiling
Cooling
Grates
SCALE CHANGE 15°F COOLER!
It’s SIMPLY
EFFICIENT!
Supports 4X Higher Heat and Power Densities
Same Layout with Passive Cooling solution implemented!
80°- 90°F
77 °- 80°F
58 °- 77 °F Zero Temp Deviation
Standard Hot Aisle - Cold Aisle with
Sealed Openings Same Room with VEDS Installed
CFD Analysis HACA vs. Passive Cooling
Standard Data Center Temperature Variation 86
83
81
78
75
72
70
67
64
62
59
°F
Typical 72 to 73°F Setpoint
Increase Economization Through Higher Set Points
Temperature Variations with VED Isolation
77°F Setpoint
Zero
standard
deviation
between
the
plenums!
Increase Economization Through Higher Set Points
What about LEED points?
Possible Points Category
15 Sustainable Sites
5 Water Efficiency
17 Energy and Atmosphere
13 Materials and Resources
15 Indoor Environmental Quality
5 Innovation and Design
69 Total Possible Points
We contribute
3 to 8 points.
LEED Points
LEED Point Certification Levels
Level Required Points
Certified 26 - 32
Silver 33 - 38
Gold 39 - 51
Platinum 52 - 69
Energy Savings Points
10.5% 1
14% 2
17.5% 3
21% 4
24.5% 5
28% 6
31.5% 7
35% 8
38.5% 9
42% 10
• Remove hot air
– Rely on server fans and high flow doors or no doors
– Avoid cable congestion – Biggest Problem!
– Do not use Top Mount Fans
Cabinet Air Flow Best Practices
• Prevent hot air re-circulation (internal and external)
– Use filler panels
– Seal off sides of equipment
– Use side panels in bayed cabinets … if required
• Deliver chilled air to critical point of use
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