How to Investigate Rising PUE and WUE in a Data Centre Malaysia
How to Investigate Rising PUE and WUE in a Data Centre Malaysia
Content
A rising Power Usage Effectiveness or Water Usage Effectiveness value does not automatically mean that one cooling machine has failed.
Changes in IT load, commissioning activity, weather, cooling-system control, water leakage and metering quality can all affect these indicators.
Before replacing equipment or changing operating setpoints, data-centre teams in Malaysia should confirm that the measurements are valid and identify which part of the facility is driving the increase.
What Are PUE and WUE?
Power Usage Effectiveness
PUE compares total data-centre energy with the energy consumed by IT equipment:
PUE = Total Data Centre Energy ÷ IT Equipment Energy
A rising PUE means that supporting infrastructure is consuming more energy relative to the IT load.
Water Usage Effectiveness
WUE generally relates data-centre water usage to IT energy consumption.
The precise boundary and calculation method must be defined because facilities may include or exclude different water uses.
Water may be consumed by:
Cooling towers
Evaporative cooling
Humidification
Water treatment
Equipment cleaning
Makeup water
Other supporting processes
PUE and WUE should be reviewed together because an energy-saving cooling strategy may use more water, while a water-saving strategy may consume more electricity.
Start by Confirming the Calculation
Before investigating equipment, verify the data.
Check:
PUE and WUE formulas
Measurement boundaries
Meter locations
Reporting period
IT energy data
Facility energy data
Water-meter data
Missing readings
Estimated values
Unit conversions
Data aggregation
A metric may appear to worsen after a metering correction identifies consumption that was previously omitted.
Use the Same Measurement Boundary
Monthly or annual results are only comparable when they use the same boundary.
Possible inconsistencies include:
Adding a new cooling plant
Excluding generator testing
Including office or warehouse electricity
Changing the IT power source
Adding tenant equipment
Moving a water meter
Including irrigation or domestic water
Altering the reporting period
Document every change before comparing the current value with historical data.
Check Whether IT Load Has Changed
Both PUE and WUE use IT energy as a reference.
If IT load decreases while supporting infrastructure continues operating, the ratios may worsen.
Review:
Installed IT capacity
Actual IT power
Rack occupancy
Average rack density
Server utilisation
Planned shutdowns
Migration activity
Commissioning status
A low-load data centre may have higher PUE and WUE even when its absolute electricity and water consumption has not increased significantly.
Compare Ratio and Absolute Consumption
Do not investigate only the headline ratios.
Review:
Total electricity use
IT electricity use
Cooling electricity use
Total water use
Makeup water
Cooling-tower bleed
Operating hours
Weather conditions
This distinction is important:
The ratio can increase because IT load falls.
Absolute consumption can increase because cooling or water use rises.
Both can worsen simultaneously.
Each situation requires a different response.
Step 1: Break Down Electrical Consumption
Separate the major loads where metering is available:
IT equipment
Chillers
Cooling towers
Pumps
CRAC or CRAH units
UPS losses
Transformers
Lighting
Humidity control
Other building services
Determine which supporting load has increased.
If only total-facility power is measured, portable electrical testing and temporary submetering may be needed to locate the change.
Step 2: Review Cooling-Plant Operation
Check:
Number of operating chillers
Chiller loading
Supply and return temperature
Temperature difference
Pump status
Pump differential pressure
Cooling-tower fan operation
Condenser-water temperature
Bypass flow
Setpoints
Equipment staging
Possible causes of excessive energy include:
Too many chillers operating
Low temperature setpoints
Poor chiller staging
Excessive pumping
Fixed-speed operation
Reduced heat-exchanger performance
Dirty coils or filters
Incorrect control sequences
Step 3: Check Airflow Management
Poor airflow can increase cooling energy even when room temperature appears acceptable.
Inspect:
Hot- and cold-aisle separation
Containment doors
Blanking panels
Cable openings
Raised-floor leakage
Perforated floor tiles
Rack inlet temperatures
Return-air temperature
Fan speed
Empty rack spaces
Bypass air returns to the cooling unit without removing sufficient IT heat. Recirculated hot air may cause local hot spots and force the system to overcool the entire room.
Step 4: Measure Temperature Distribution
Do not rely only on a wall-mounted room thermostat.
Measure or log temperature at:
Bottom of rack inlet
Middle of rack inlet
Top of rack inlet
Rack outlet
End of aisle
Suspected hot spot
Cooling-unit supply
Cooling-unit return
Temperature differences help identify:
Air recirculation
Poor distribution
Overcooling
Inadequate airflow
Local high-density loads
A thermal camera can support the inspection, but contact or air-temperature measurements are still required for quantitative assessment.
Step 5: Review Humidity Control
In Malaysia’s humid climate, humidity control can add substantial cooling demand.
Check:
Relative-humidity sensors
Dew-point control
Dehumidification
Reheating
Humidification
Outdoor-air leakage
Door operation
Control deadbands
Simultaneous humidification and dehumidification is a sign that control systems may be working against each other.
Verify sensors before changing humidity setpoints.
Step 6: Investigate Water Consumption
Break water use into categories where possible:
Cooling-tower makeup
Blowdown
Humidification
Domestic use
Cleaning
Irrigation
Fire-system testing
Water treatment
Leaks
If one meter covers the entire site, it may be difficult to determine whether the data centre itself caused the increase.
Submetering major water uses improves WUE analysis.
Step 7: Check Cooling-Tower Operation
A cooling tower loses water through:
Evaporation
Blowdown
Drift
Leakage
Review:
Makeup-water volume
Blowdown rate
Cycles of concentration
Conductivity control
Float valve
Basin level
Drift eliminators
Water-treatment settings
Visible overflow
Pipe and valve leakage
Excessive blowdown can increase WUE. Reducing it without controlling water chemistry may create scale, corrosion or microbiological problems.
Step 8: Check for Hidden Leaks
Water loss may occur from:
Pipe joints
Valves
Pump seals
Heat exchangers
Cooling-distribution units
Drain lines
Storage tanks
Overflow
Automatic top-up systems
Underground pipes
Warning signs include:
Frequent top-up
Falling tank level
Damp areas
Staining
Unexpected meter flow
Pump operation during low demand
Rising chemical usage
A small continuous leak can create a significant annual water loss.
Step 9: Review Water-Meter Accuracy
Investigate:
Meter type
Installation direction
Pipe-full condition
Straight-pipe requirements
Flow range
Pulse or communication configuration
Calibration status
Data gaps
Unit conversion
Duplicate counting
A meter operating below its specified minimum flow may fail to record accurately.
Compare site meters with utility bills and perform a water balance where practical.
Step 10: Examine Water Chemistry
Water quality affects cooling efficiency.
Relevant parameters may include:
pH
Conductivity
TDS
Hardness
Alkalinity
Chloride
Turbidity
Suspended solids
Microbiological condition
Treatment-chemical concentration
Poor water treatment may cause:
Scaling
Corrosion
Biofilm
Blocked heat exchangers
Reduced cooling efficiency
Increased blowdown
Leakage
Portable water-quality instruments can support routine checks, but specialist laboratory analysis may be needed for complete treatment control.
Step 11: Check Pumps and Rotating Equipment
Pump deterioration may reduce flow or increase energy consumption.
Inspect:
Vibration
Bearing temperature
Motor current
Pressure
Flow
Seal leakage
Alignment
Unusual sound
Possible problems include:
Bearing wear
Cavitation
Misalignment
Loose mounting
Impeller damage
Air in the system
Blocked filter
Valve restriction
Compare pump condition with its historical baseline.
Step 12: Review Weather and Seasonal Conditions
External conditions can affect both energy and water use.
Record:
Outdoor dry-bulb temperature
Relative humidity
Wet-bulb temperature
Rainfall
Haze or air contamination
Seasonal cooling demand
A higher WUE during hot and dry conditions may be expected in evaporative systems. Malaysia’s high humidity can also affect cooling and dehumidification performance.
Compare similar weather periods rather than comparing months without context.
Step 13: Check Commissioning and Maintenance Activity
Temporary increases may be caused by:
New data-hall commissioning
Cooling-system flushing
Equipment testing
Generator testing
Chiller maintenance
Water-treatment work
Partial shutdown
Redundancy testing
Sensor replacement
Cleaning
These events should be recorded so that they can be separated from normal operating performance.
Step 14: Verify Sensors Before Changing Controls
Check installed sensors against suitable portable instruments.
Verify:
Temperature
Relative humidity
Differential pressure
Water conductivity
pH
Flow
Electrical current
Pressure
A drifting temperature or pressure sensor may cause a controller to increase cooling unnecessarily.
Practical Investigation Sequence
When PUE or WUE rises:
Confirm formulas and boundaries.
Compare ratios with absolute consumption.
Check IT load.
Identify the electrical or water category that increased.
Review commissioning and maintenance events.
Inspect cooling and airflow.
Check for leakage.
Verify installed sensors.
Review weather and production conditions.
Make one controlled change at a time.
Measure the result.
Document the corrective action.
Changing several setpoints simultaneously makes it difficult to determine which action improved or worsened performance.
Measurements to Record
A useful investigation record may include:
Total facility power
IT power
Cooling power
Total water
Cooling-tower makeup
Blowdown
IT occupancy
Rack density
Supply and return temperatures
Relative humidity
Differential pressure
Chiller and pump status
Outdoor weather
Water conductivity and pH
Leak observations
Maintenance events
Trend data is normally more useful than one isolated inspection.
Instruments for PUE and WUE Investigation
Useful product categories include:
Thermal imaging cameras
Temperature and humidity data loggers
Contact thermometers
Differential-pressure meters
Airflow meters
Clamp meters
Power and electrical testers
Water-quality meters
Leak-detection sensors
Vibration meters
Network and cable testers
Formal PUE and WUE calculation still requires appropriate fixed metering and clearly defined reporting boundaries.
Data Centre Testing Instruments from MTM Precision
MTM Precision supplies instruments for data-centre commissioning, facility inspection and preventive maintenance in Malaysia.
Relevant products include:
NOYAFA NF-522 thermal imaging camera
Temperature and humidity meters
Temperature and humidity data loggers
Differential-pressure meters
Airflow and anemometer instruments
Clamp meters and electrical testers
Portable pH, conductivity and TDS meters
Leak-detection equipment
Vibration meters for cooling pumps and fans
NOYAFA NF-8209 Pro and NF-8506 network cable testers
NOYAFA NF-IPC728HSO CCTV and network tester
The appropriate instrument combination depends on whether the problem is thermal, airflow-related, electrical, water-related or caused by unreliable sensor data.
Contact MTM Precision
MTM Precision Sdn. Bhd. (744811-A)
Tel: 03-8080 7172
WhatsApp: +6016-660 7346
Email: mtmpre@yahoo.com / enquiry@mtmpre.com.my
Website: www.mtmpre.com.my
Visit our Puchong Showroom & Service Centre for data-centre testing instrument selection, demonstration and technical support.
Operating hours: Monday to Friday, 9:00 AM–6:00 PM.
20 Sep 2026
