©2009 HP Confidential template rev. 12.10.091©2009 HP Confidential

Norival A Corrêa, Lead Energy Efficienty EngineerHP Critical Facilities Servicesnorival.correa@hp.com+ 55 11 9 9618 8720

Monday, March 29, 2012

LEED – Design Consideration of Applying Airside and Waterside

Economizer to Data Center

2

Typical Data Center Cooling Setup

3

Data Center Free Cooling Economizer Type

– Airside Economizers• Direct Air• Indirect air-to-air heat exchanger (Rotary heat wheel, Fixed plate cross-flow heat exchanger

• Direct evaporation• Indirect evaporation

– Waterside Economizers• Parallel (Non-integrated)• Series (Integrated)

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Data Center Free Cooling Economizer Type

– Airside Economizers• Direct Air• Indirect air-to-air heat exchanger (Rotary heat wheel, Fixed plate cross-flow heat exchanger

• Direct evaporation• Indirect evaporation

– Waterside Economizers• Parallel (Non-integrated)• Series (Integrated)

©2009 HP Confidential template rev. 12.10.095 ©2009 HP Confidential5

Kyoto Cooling

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Kyoto Cooling Setup

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Kyoto Cooling Setup

©2009 HP Confidential template rev. 12.10.098 ©2009 HP Confidential8

Airside Economizer

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Direct Airside Economizer Setup

The use of Air Handling Unit (AHU) to capture outside air with low heat content to replace internal heat gain

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Direct Airside Economizer – Industrial Concerns– Maintain Humidification

• Prevent Electrostatic Discharge

– Particulate Contamination• Settling on computer server boards • Electrical shorting • Corrode the circuit board components

– Gaseous Contamination• Corrosion and ion migration at the computer circuit board

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Airside Economizer – Solutions

– Maintain Humidification• Lower minimum humidity level− From 50% RH to 40% RH

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Airside Economizer – Solutions

– Maintain Humidification• Improved humidification techniques -adiabatic − Ultrasonic

− Atomizing

− Wet Media

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Airside Economizer – Solutions

– Particulate Contamination• Test indicated the use of 85% (MERV 11) filter reduce article concentrations to nearly match the level found in data centers that do not use economizers

• Higher performance filter (95% or MERV 16) can be used

MERV value

Sources: ASHRAE 52.2-2007, Method of Testing General Ventilation Air-Cleaning Devices for Removal Efficiency by Particle Size

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Airside Economizer – Solutions

– Gaseous Contamination• Not enough studies in the IT industry to document the rate of corrosion with respect to gaseous pollution concentrations

• The use of real time gas monitoring systems are recommended− Highly sensitive quartz crystals microbalance sensor

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Direct Airside Economizer Update

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Airside Economizer – Mechanical Rm Design

– Size

– Location

– Structure support

– Water leak containment

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Airside Economizer – Mechanical Room & Outside Air Intake Design– Outside air intake

• Snow & Rain

• Bomb Blast resistant

• Hurricane resistant

– Airborne particulates• Generator flue

• Cooling tower water mist

• Roadway dust

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Airside Economizer – Data Room Design

– High concentration of air flow• Negative flow - Venturi Effect

• Higher raised floor

• Higher return plenum

Return air

AHUNeutral Room Air

Server

Cold Air

Mixed Warm Air

Hot Air

Raised Floor

Return Plenum

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Airside Economizer – Air Distribution Design

– Air Balance & Control• Use Computational Fluid Dynamics (CFD) modeling

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Airside Economizer – Fire Protection

– Fire Prevention • Fire rated wall

– Fire Detection • Photoelectric and ionization type smoke detectors • High sensitive aspirating type smoke detectors − VESDA

− Laser

– Fire Protection• Pre-action gaseous fire protection activation

©2009 HP Confidential template rev. 12.10.0921 ©2009 HP Confidential21

Waterside Economizer

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Waterside Economizer Setup

The use of cooling tower in lieu of operating a chiller or in conjunction with operating a chiller for creating chilled water to handle a cooling load when the outdoor ambient conditions allow

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Waterside Economizer Type

– Two ways to design and utilize free cooling systems• Series waterside economizer (Partial pre-cooling + Full free cooling)• Parallel waterside economizer (Full free cooling)

Series water-side economizer Parallel water-side economizer

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Waterside Economizer – Cooling Tower

– Cooling tower selection • Approach temperature increase as wetbulb temperature decrease (Capacity drop)

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Waterside Economizer – Cooling Tower

– Cooling tower sizing• Optimize for winter operation− 50% annual free cooling

− 6 cooling towers

− 40ft x 120ft Space

• Optimize for summer operation− No free cooling

− 4 cooling towers

− 40ft x 80ft Space

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Waterside Economizer – Heat Exchanger

– Heat exchanger selection and sizing• lowest approach temperature, highest potential to operate waterside economizer• Physical size• Cost• Pressure drop• Maintenance

Source: www.alfalaval.com

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Waterside Economizer – Other Design Considerations– Freeze protection and prevention

• Electrical heater / Heat trace• Recessed sump / Remote Sump

– Pump Sizing• Varies operation, varies pressure drop• Variable Frequency Drive

– Control • Switch in and out of different operation modes

©2009 HP Confidential template rev. 12.10.0928 ©2009 HP Confidential28

Indirect Airside Economizer (Munters)

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Indirect Airside Economizer Setup

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Indirect Evaporative Air Handling Unit

Supply Air To Data Center

Hot Return Air from Data Center

Supply Fan

Spray Pump

Supplement Cooling coil

Secondary Air Exhaust

Outside Air

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Indirect Evaporative Air to Air Heat Exchanger

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Indirect Evaporative Air to Air Heat Exchanger

©2009 HP Confidential template rev. 12.10.0933 ©2009 HP Confidential33

Waterside, Direct and Indirect Airside Economizers PayBack Analysis

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Airside and Waterside Economizer Comparison – Operating Criteria

Attribute Option 1: Waterside Economizer

Option 2: Direct Airside Economizer

Option 3: In-direct Airside

Economizer(Munters)

Redundancy Easy, add on option to the

chiller plantDifficult, AHU size and OA

connectionDifficult, IDE size and OA

connection

Reliability No major impact

Fault tolerance No major impact

ScalabilityHigher, heat exchanger size is

relatively smallMedium, depends on the

amount of AHULow, depends on the amount of

AHU

Expansion Higher, heat exchanger can be located outside of mechanical

room

Low. Outside air louver have to be designed day1

Low. Outside air louver have to be designed day1

Flexibility High Medium Low

Ambient conditions

Temperature & humidity ranges can be maintained per ASHRAE

35

Airside and Waterside Economizer Comparison – Data Center Design

Attribute Option 1: Waterside Economizer

Option 2: Direct Airside Economizer

Option 3: In-direct Airside

Economizer(Munters)

Building Size

No major impact

Need more real estate

Building Structure Need additional structure support

Plenum ceiling and raised floor height

Need sufficient height to allow high volume of air movement

Humidification Need additional humidification

No major impactAir quality Need additional filtration

Fire protectionNeed more fire and smoke

detection

Computer placement Same precaution. Less

impact Avoid being too close to AHU discharge

36

Airside and Waterside Economizer Comparison – Mechanical Plant Design

Attribute Option 1: Waterside Economizer

Option 2: Direct Airside Economizer

Option 3: In-direct Airside

Economizer(Munters)

Maintenance Low Significantly more Medium

System control Medium Relatively easy Most complex

Water consumption

High Low Medium

Power consumption

Low Medium High

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Airside and Waterside Economizer Comparison – Others

Attribute Option 1: Waterside Economizer

Option 2: Direct Airside Economizer

Option 3: In-direct Airside

Economizer(Munters)

Equipment lead time

Short Medium Long

Construction time

Short Long Long

Retrofit Easy Hard Medium

Cooling densitySuitable for future high density applications

Suitable for low to medium density applications

Suitable for low to medium density applications

©2009 HP Confidential template rev. 12.10.0938 ©2009 HP Confidential38

THANK YOU!!QUESTIONS??

Norival A Corrêa, Lead Energy Efficienty EngineerHP Critical Facilities Servicesnorival.correa@hp.com+ 55 11 9 9618 8720

Monday, March 29, 2012

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