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Room Cooling in the Data Center

Containment Strategies to Improve

Performance

Joe Capes

Director – Business Development, Americas

Cooling Line of Business

Archive www.missioncriticalmagazine.com

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Room Cooling in the Data Center

Containment Strategies to Improve

Performance

Joe Capes

Director – Business Development, Americas

Cooling Line of Business

5

Agenda

●Data Center Cooling Trends

●Containment Methodologies

●Economizer Technologies

●Economic Considerations

●Final Recommendations

6

Agenda






7

Traditional Data Center Cooling Methods

• Many data center professionals have inherited traditional data centers

Characteristics of Traditional Cooling

• Designed with energy efficiency as a low priority

• Cooling units located at outside perimeter • Raised floor • Hot air mixes with cold air • Inconsistent hot / cold aisle arrangement • Oversized power and cooling components • Low IT rack power densities

Present Trends

• New emphasis on high efficiency and low carbon emissions • Row cooling and separation of hot and cold air streams are new

breakthrough technologies to help to remedy the situation

Introduction

8

Today’s Main Cooling Architectures for Air-

cooled Servers

Central Air Handling Unit

Room Based Architecture

Computer Room Air Handler

Room Based Architecture

InRow Air Handler

Row Based Architecture

9

Room Row Rack

Different Cooling Architectures for Air-

Cooled Servers ● The two main cooling equipment functions are to…

● Provide the bulk cooling capacity

● Distribute the air to the IT loads

● The major difference in architectures lies in how they perform the second task. ● Airflow is crudely constrained by room design, is not visible in

implementation, and varies considerably between installations.

Floor plans showing the basic concept of room,

row, and rack-oriented cooling architecture.

10

Raised Floor Architecture for Air Distribution

One such possible constraint…

11

Capacity Utilization

Claimed Capacity vs. Usable Capacity

0%

20%

40%

60%

80%

100%

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

Average Per-Rack Power Density (kW)

Usab

le C

RA

C C

ap

acit

y

row-oriented cooling

rack-oriented cooling

rooom-oriented cooling

Usable air conditioner capacity as a function of average

rack power density for the three cooling architectures

12

A Hybrid Approach to Cooling

● Most Data Centers will have a mix of heat densities and therefore

cooling solutions

● IT Refreshes happen every 2-4 years resulting in a mix of distributed

IT assets

● IT management of blades and storage deployments is often in

clusters

● Concentrated high density loads

● Traditional server assets may be well served by room cooling units

d

Row-

oriented Rack-

oriented

Room-

oriented

13

World Power Consumption Growth Ranking

Data Centers Average % Projected Growth in Power Growth 2011-2012 (Data Center Dynamics)

Actual Projected Sample kw/Rack

●1st Turkey 85% (60%) 110 MW 3.61 kW

●2nd Colombia 50% (40%) 90 MW 3.60 kW

●3rd Brazil 48% (45%) 280 MW 3.05 kW

●4th China 46% (28%) 500 MW 2.75 kW

●5th Argentina 41% (36%) 120 MW 3.14 kW

●9th Eastern USA 22% (13%) 320 MW 4.35 kW

●22nd Western USA 2% (3%) 100 MW 5.32 kW

14

Room Cooling

● Ducted supply air for delivery to heat load

● Open or ducted return air for heat removal

● Fixed fan speeds to deliver consistent plenum

pressures

● Airflow restrictions in under floor plenum

● Non-uniform airflow distribution

● Fixed flow tiles/grates

● Limited capacity resolution

● Delivery of colder air to the space

● Reduced Sensible Heat Ratio (SHR)

CRAC/CRAH Airflow Configurations

Front Suction with

Top Discharge

Bottom Suction

with Top Discharge

Front Suction with

Top Front Discharge

(Plenum and Grille)

Rear Suction with

Top Discharge

Top Suction with

Bottom Discharge

(Plenum and Grille)

Top Suction with

Bottom Discharge

(Floorstand)

UP

FL

OW

D

OW

NF

LO

W

16

CRAC/CRAH Checklist

High efficiency in all operating conditions

Optimized air flow management with EC fans

Compact dimensions

Front service access only

Competitively priced

1rst Year Parts/Labor/Travel

17

Agenda






The two basic approaches to airflow containment

COLD-aisle containment HOT-aisle containment

The key benefit of both methods comes from SEPARATION of

cold supply air from hot return air

COLD air free in the room

HOT air free in the room

Cold aisle

Hot aisle

19

Common Characteristics:

• Prevent Hot and Cold air streams from mixing

• Cooling systems can be set to a higher temperature

• Reduction of humidification and dehumidification costs

• Better overall physical infrastructure utilization that enables rightsizing

Those benefits lead to energy savings and better equipment utilization compare to traditional cooling methods

Containment Approaches

Hot and cold containment force different operating temperatures

If personnel space temperature is held constant, then hot containment

allows higher air conditioner operating temperatures

If person

is 25 C

If person

is 25 C

Return is

25 C

Return is

35 C

Supply is

15 C Supply is

25 C

COLD-aisle containment HOT-aisle containment

21

CACs Unique Characteristics

• Typically used with traditional perimeter cooling – cold air supplied via raised floor and perforated tiles. Alternatively CACS is designed with row based cooling system

• The rest of the room becomes large, return hot air plenum

Cold Aisle Containment Limitations • Perimeter Cooling – Longer air paths and higher air pressure resistance -

higher power consumption by fans • Less than optimum return air temperature – lower cooling capacity and

efficiency • Limited power density per rack - limited by the raised floor and perforated

tiles • Limited predictability – variable room and raised floor dimensions • Limited ride through during cooling failure - confined to Cold Aisle air volume • Room acts as the Hot Aisle – contradicts with perception that data centers should

be cold. Peoples’ expectation when entering the room need to be adjusted. • Room acts as the Hot Aisle – difficulty in cooling free standing racks and

equipment • Not modular & scalable due to room cooling architecture

Cold Aisle Containment System (CACS)

22

HACs Unique Characteristics

• APC by Schneider Electric holds the concept patent • Often used with Row cooling – hot air is captured and neutralized via cooling units

placed within the row of racks and supplied to cold aisle • The rest of the room becomes large, cold air plenum, no raised floor or ducting is

required Hot Aisle Containment Advantages • In-Row Cooling is Closed Coupled: Short air paths and low air pressure

resistance - lower power consumption by fans (See White Paper #130) • Higher return air temperature – higher cooling capacity and efficiency of the

cooling system • High power density per rack – all heat is neutralized and there is no limitation

with the raised floor and perforated tiles • Predictable solution – independent of room and raised floor dimensions • Higher ride through during cooling failure – significantly larger cold aisle air volume • Room acts as the Cold Aisle – in agreement with the perception that data centers

should be cold Continued....

Hot Aisle Containment System (HACS)

23

Hot Aisle Containment Systems (HACS)

InfraStruXure High Density

InfraStruXure InRow RC

In-Row Air Conditioner Cools hot

chamber air

Chamber Doors

Access to hot aisle, locks for

security

Hot Aisle Ceiling Tiles/Cable Trough

Seals in hot air, prevents

mixing with room air

● High Density Zones

● Supports InRow products

● Hot air scavenging system

● Ducted Return / Free Supply

● Optimize InRow Cooling

● Increase efficiency

● Improve predictability

● Use at any density

24

Agenda






25

Trends - Economizers

• Air Side Economizer • Requires ‘cool enough’ outside air to

maintain desired temperature in data center

• Outside DRY BULB temperatures from

40°F (4.4°C) to 80.6°F (27°C)

• Humidity control required when outside of

control range typically less than 40% or greater than 60% RH

• Requires pre-treatment & filtration of outside air to mitigate

potential for particulate contamination within data center

• Need to have ‘control’ of the real estate and zoning regulations

around you

• Water Side Economizer • Requires ‘cool enough’ outside air to chill water/glycol

• Outside WET BULB temperatures 40°F (4.4°C) to 64.4 F (18°C)

26

Economizer Requirements

None - 1a, 1b, 2a, 3a, 4a

> 19kW - 3b, 3c, 4b, 4c, 5b, 5c, 6b

>40kW - 2b, 5a, 6a, 7, 8

27

ASHRAE 90.1 Climate Zone Economizer Requirement Map

No requirement

Data Centers >19kW

Data Centers >40kW

Basically, if you’re blue, economizer use is mandated!

28

Economizers – Summary of Legacy

Situation

●Complex infrastructure

requires special controls,

installation, and maintenance

●Multiple vendors involved

●These systems have a higher

chance of failure and

emergency maintenance

Custom Economizer Systems

Complex System

Economizers – Installations into

Existing Data Centers Cooling

Equipment

Type

Water Side

Economizer

Air Side

Economizer Comment

Direct Expansion

Large External Air

Handling System Not Practical Possible

Additional coil sections would be required making it impractical to consider a water side

economizer. An air handling system located outside or within close proximity makes

consideration of outside air economizer possible.

Traditional Floor

Mounted

CRAC/CRAH

Not Practical Not Practical

Dual coils are required to implement a waterside economizer on a DX system, and would

require additional coils to be added or units replaced. Typically, CRAC/CRAH units are in

the interior of the building and would not lend themselves to ducting to the outdoors for air

side economizer.

Close Coupled

Cooling Not Practical Not Practical

Dual coils are required to implement a water side economizer on a DX system, and would

require additional coils to be added or units replaced. Close coupled units are installed

within the rows of IT equipment making it difficult to access outside walls and provide

ducting to support an air side economizer.

Chilled Water

Large External Air

Handling System Likely Possible

Adding a plate and frame heat exchanger with valves and controls is likely to be considered

with a chilled water system. An air handling system located outside or within close

proximity makes consideration of outside air economizer possible.

Traditional Floor

Mounted

CRAC/CRAH

Likely Not Practical

Adding a plate frame heat exchanger with valves and controls is likely to be considered

with a chilled water system. Typically CRAC/CRAH units are in the interior of the building

and would not lend themselves to ducting to the outdoors for air side economizer.

Close Coupled

Cooling Likely Not Practical

Adding a plate frame heat exchanger with valves and controls is likely to be considered

with a chilled water system. Close coupled units are installed within the rows of IT

equipment making it difficult to access outside walls and provide ducting to support an air

side economizer.

30

Economizer Competitive Analysis

1.09 466,518 45%

1.10 503,999 48%

1.14 728,195 70%

1.16 846,039 81%

Fresh Air Econ 1.14 718,159 69%

1.20 1,044,073 100%

5) All system have fan control proportional to IT load % of design

Relative

PowerPartial PUE kW-Hr/Yr

4) Does not reflect humidification losses

EcoBreeze

Air Econ w/ Heat Wheel

Water Cooled Chiller w/ Econ

Air Cooled Chiller w/ Econ

DX Fluid Cooled CRAC w/ Econ

1MW Design Data Center @ 60% Load

1) Hot Aisle Containment 101.5°F Return to A/C

2) Supply Air / Cold Aisle 77°F

3) Bin Weather Data Saint Louis, MO

System Architecture

31

Agenda






32

Financial Comparison

● Data Center Sizes – 60, 120, 480, 1200 kW

● Rack Density – 3, 6, 12, 20 kW per Rack (120 CFM/kW)

● Raised Floor Air Distribution for Room Cooling – 100 Euro/ m2 ($8/ft2)

● Raised Floor Pricing range from 30 Euro / m2 to 400 Euro / m2($50/ft2)

● Does not consider fire suppression under floor ($4-$10/ft2)

●Drop Ceiling for Room Cooling Hot Aisle Containment – 36 Euro / m2 ($4/ft2)

● Based on RSMeans Cost Works Data Base – Typical Drop Ceiling

● Does not consider fire suppression in drop ceiling range ($4-$10/ft2)

●Active Floor for Room Cooling with CAC and raised floor for high density (12

and 20 kW per rack)

●Piping costs based on RSMeans Cost Works Data Base – Steel Piping

● Cost of Energy = 0.1 Euro / kWh

●EcoStream Analysis Tool used to determine airflow required for each scenario

Benefits of Containment – Room Cooling

€ 290,000.00

€ 310,000.00

€ 330,000.00

€ 350,000.00

€ 370,000.00

€ 390,000.00

€ 410,000.00

€ 430,000.00

€ 450,000.00

3 kW 6 kW 12 kW 20 kW

Fir

st

Co

st

Density (per Rack)

480 kW Data Center - First Cost

Room w/ raised floor

Room CAC w/active floor

Room HAC no Raised Floor

Room HAC w/ raised floor

€ 60,000.00

€ 65,000.00

€ 70,000.00

€ 75,000.00

€ 80,000.00

€ 85,000.00

3 kW 6 kW 12 kW 20 kW

An

nu

al

Op

era

tin

g C

ost

Density (per Rack)

480 kW Data Center - Operating Cost

Room w/ raised floor

Rooom CAC w/active floor

Room HAC no raised floor and Room HAC w/ raised floor

First Cost

• Higher first cost of adding containment to

room cooling

• Room Cooling with no raised floor and Hot

Aisle Containment (HAC) most cost

effective solution

Operating Cost Improvement

• HAC no raised floor ROI over raised floor • 3 kW per Rack = 3 years

• 6 kW per Rack = 1.5 years

• CAC with raised ROI over raised floor • 3 kW per Rack = 4.3 years

• 6 kW per Rack = 2.5 years

Effect of Active

Air Distribution

Annual Operating Costs

€ -

€ 2,000.00

€ 4,000.00

€ 6,000.00

€ 8,000.00

€ 10,000.00

€ 12,000.00

3 kW 6 kW 12 kW 20 kW

An

nu

al

Op

era

tin

g C

ost

Density per Rack

60 kW Data Center

€ 10,000.00

€ 12,000.00

€ 14,000.00

€ 16,000.00

€ 18,000.00

€ 20,000.00

€ 22,000.00

€ 24,000.00

3 kW 6 kW 12 kW 20 kW

An

nu

al

Op

era

tin

g C

ost

Density per Rack

120 kW Data Center

€ 50,000.00

€ 55,000.00

€ 60,000.00

€ 65,000.00

€ 70,000.00

€ 75,000.00

€ 80,000.00

€ 85,000.00

3 kW 6 kW 12 kW 20 kW

An

nu

al

Op

era

tin

g C

ost

Density per Rack

480 kW Data Center

€ 130,000.00

€ 140,000.00

€ 150,000.00

€ 160,000.00

€ 170,000.00

€ 180,000.00

€ 190,000.00

€ 200,000.00

3 kW 6 kW 12 kW 20 kW

An

nu

al

Op

era

tin

g C

ost

Density per Rack

1200 kW Data Center

35

Agenda






36

• Hot Aisle and Cold Aisle Containment eliminate air mixing and are a superior solution compared to traditional cooling architecture

• Hot Aisle Containment System (HACS) is a more efficient approach than Cold Aisle Containment System (CACS) because the HACS methodology allows for the channelling the hottest air directly into coolers

• HACS used with In-Row cooling architecture provides closed couple cooling that allows higher cooling capacity utilization and efficiency

• HACS is more flexible, it can be deployed anywhere within the room, it is more predictable and scalable solution, it better addresses the higher IT density requirements

• HACS has higher potential for better heat utilization and using free cooling approaches

• Hot Aisle Containment has better ride through capability

CACs vs. HACs Summary

37

Characteristic Cold Aisle Containment Hot Aisle Containment Comment

Efficiency improvements

Yes Yes

HACS is more efficient than CACS because HACS typically operates at a higher return

temperature due to isolation of the hot air from the rest of the room.

Ability to increase cold air supply set

point without impacting entire data

center No Yes

With HACS, cooling set points can be set higher while still maintaining a comfortable

work environment. Increasing CACS cooling set points results in uncomfortably high

data center environment.

Leverages maximum number of

potential free cooling days

No Yes

By increasing cooling set point, containment systems allow for increased free cooling.

However, increasing the set point of CACS results in increased room temperatures

which is undesirable from a free cooling day perspective.

Room neutral solution

No Yes

A HACS deployment is a “drop-in” solution. CACS impacts the surrounding data center

infrastructure.

CACs vs. HACs Head to Head

38

Characteristic Cold Aisle Containment Hot Aisle Containment Comment

Ease of deployment with room

cooling

Yes No CACS is preferred when using room level cooling with a

free return system which draws its return air from the room.

A HACS without in-row cooling would require special return

duct work or ceiling plenum.

Ability to scale for high density No Yes CACS is often implemented with raised floor and inefficient

fan assisted floor tiles are needed in order to achieve higher

density.

Room neutral design No Yes HACS is “room neutral”—it does not impact the outside

room temperature in any way. CACS makes the air outside

of the contained rows hotter.

Adverse temperature impact on non-

racked equipment

Yes No With CACS, because the cold aisles are contained, the rest

of the data center is allowed to become hot. Equipment

outside the contained areas would have to be evaluated for

operation at elevated temperatures.

Head to Head (cont.)

39

Existing Data Center Suggestions (Brown Field)

Out of Capacity Stranded Capacity

Low Density

0-6 kW per Rack

High Density

> 6 kW per Rack

Add Room Cooling Cold Aisle Containment

Close Coupled

Cooling Zone for Rack

Expansion or Existing

Racks

Cold Aisle Containment

+ Active Floor

Air Removal Unit or

Vertical Exhaust

Duct(VDE)

IT Load to be

Deployed

40

Final Recommendations

● Always use containment for optimal TCO

● Payback is immediate with close coupled cooling

● 3 year ROI for Room Based Cooling improves with density

●Hot Aisle Containment preferred approach for new data center builds

● Eliminates variable of cold air distribution with or without raised floor

● Improved Flexibility keeping data center cool available for non-racked

equipment and personnel comfort.

●Cold Aisle Containment – Retrofit for existing data center

● Adapt to existing room cooling systems

● Active floor to assist with cold air distribution from raised floor to ensure

sufficient air flow is available in contained aisle.

● Efficiency Gains Require elevating room temperature

41

● Additional details available at whitepapers.apc.com

[email protected]

Thank You!

apc cooling

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