Excool presentation given at DCW 2014 in conjunction with Digital Realty.

1. • 100% free cooling
• lower cost
• increased resilience

2. The largest energy consuming element apart from the IT load is the Compressor!!
TRADITIONAL chilled water system
SOLUTION – reduce or completely remove dependency
on mechanical cooling
IT Load
Electrical losses
Cooling
PUE = 2.0

3. The largest energy consuming element apart from the IT load is the Compressor!!
SOLUTION – reduce or completely remove dependency
on mechanical cooling
IT Load
Electrical losses
Cooling
PUE = 1.15
INDIRECT Adiabatic system

4. • Leverage natural cooling
properties of outdoor air
but keep contamination
out
INDIRECT
• Decrease effective
temperature of outdoor
air in summer by
increasing moisture
content
ADIABTIC &
EVAPORATIVE
INDIRECT adiabatic & evaporative

5. TYPICAL arrangement
Reproduced with kind permission of
Nicholas Webb Architects and Digital Realty

6. EXCOOL winter operation
• Hot return air indirectly cooled by cold outdoor air

7. EXCOOL summer operation
• Warm outdoor air cooled by addition of moisture

8. EXCOOL extreme temperature
• Supply air cooling supplemented by ‘top-up’ DX pack

9. SECONDARY air at summer peak
UK design ambient condition
Heat exchanger entering
condition
35°C
25% RH
21°C

10. EXCOOL mechanical cooling thresholds

11. Global peak wet bulb temperatures
°C wb
35
30
25
20
15
For units running at full speed based on ASHRAE TC9.9 environmental envelopes and return temp 12°C above supply
temp.
EXCOOL mechanical cooling thresholds
A
R
24
THRESHOLDS
A = ASHRAE Class 1 allowable
R = ASHRAE recommended
24 = 24°C supply temperature

12. OPERATIONAL thresholds
Compressoractivationpointtomaintain24°Csupply
Adiabaticactivationpointtomaintain24°Csupply
-10 -5 0 5 10 15 20 25 30
Wet bulb temperature (°C)
Wet bulb temperature frequency - Annual
LONDON/HEATHROW AIR, United Kingdom (037720)
Compressoractivationpointtomaintain27°Csupply

13. PUE – Power usage effectiveness
PUE = Total Facility Power
IT Equipment Power
The average Power Usage Effectiveness (PUE) rating for data centres is
1.8, according to a survey of more than 500 data centres conducted
by The Uptime Institute
pPUE = IT Equipment Power + cooling system power
IT Equipment Power
Typical Free cooling chiller system in London estimated pPUE = 1.20

14. City % Free Cooling Mech Cooling Hours pPUE
Recommended Allowable Recommended Allowable
London 100 100 0 0 1.025
Paris 99.95 100 4 0 1.026
Amsterdam 99.99 100 1 0 1.025
Madrid 99.95 100 4 0 1.027
Moscow 100 100 0 0 1.022
New York 97.91 100 183 0 1.034
Riyadh 99.95 100 4 0 1.066
• ‘Recommended’ and ‘Allowable’ refer to the environmental control envelopes recommended by ASHRAE TC 2011
Thermal Guidelines for Data Processing Environments
• Based upon 1MW IT load running at an annualised average of 75%
• Data Source ASHRAE weather data viewer 4.0
• Supply temp 24°C, return 36°C. Supply temp allowed to rise to 27°C (recommended) and 32°C (allowable).
• Aisle containment in place maintaining a 12K ΔT between supply and return.
• Resilience based on N+1 and pPUE calculated with all units running.
• pPUE = (Cooling input power + IT power ) ÷ IT power
EXCOOL global efficiency
Key observation – PUE of ≤ 1.15 achievable in many locations

15. Additional Energy
Mechanical cooling and
Humidification
DIRECT air – viable alternative?
Contamination Risk
Forest fire in Moscow
shrouds city in smoke for
several weeks in 2010.
Outdoor air systems in full
re-circulation with 100%
mechanical cooling.Mechanical Cooling
and dehumidification
Humidification
Silver Sulfide generated
corrosion leading to copper
creep and silver whisker
growth ultimately resulting
in server failure.*
*Randy Schueller – Dell – Creep
Corrosion on Lead Free Printed Circuit
Boards in High Sulfur Environments
Oct 2007
Corrosion of Silver
Soldered Joints
due to Sulphur based
gaseous contamination and
high humidity/ temperature.*

16. • Full mechanical
cooling support
required
Traditional
chilled water
and direct air
• 25% ‘top-up’ for
extreme days
only. Runs for 4
hours per year
EXCOOL in
Madrid
• No mechanical
cooling required
– 100% ‘free’
cooling
EXCOOL in
London
MECHANICAL cooling reduction
Based on ASHRAE TC9.9 recommended envelope and ASHRAE WD view 4.0
weather data.

17. • 60% reductionGenerator
• 70% reductionTransformer
• Reduced in sizeDiesel storage
ELECTRICAL infrastructure reduction
Relative to traditional chilled water and direct air systems.

18. CAPITAL cost saving
London 1MW Data Centre Cooling Approximate Capital Costs €
Values are approximate and for comparative purposes only. Costs may vary depending upon data centre design,
equipment specification and selection and site conditions
£-
£200,000.00
£400,000.00
£600,000.00
£800,000.00
£1,000,000.00
£1,200,000.00
Free Cooling
Chillers
Excool
BMS Points
Water Storage
Electrical System
Pumps and pipes
CRACs
Main Plant

19. OPERATIONAL cost saving
£-
£20,000.00
£40,000.00
£60,000.00
£80,000.00
£100,000.00
£120,000.00
£140,000.00
£160,000.00
Free Cooling
Chillers
Excool
Annual Maintenance
Running Costs
London 1MW Data Centre Cooling Approximate Operational Costs
Values are approximate and for comparative purposes only. Costs may vary depending upon local energy and
labour costs. Running costs are based on £0.10 per kWh and £1.00 per m3 water.

20. • Auto drain down
• Auto purge
• Biological Filter
• Anti scale system
Integrated
System and
Software
• Annual consumption at
75% average load = 1500m3
per MW IT load in London.
Equivalent to domestic
consumption of 30 people
Water
quantity
• No adiabatic cooling
required in winter so no risk
of freezing.
Frost
control
• Integrity of water supply to be
considered. Water store
ideally buried to maintain
ground water temperature.
Water
storage
INTEGRATED water treatment
Approved by Legionella Control Association of Great Britain

21. • Inspect and clean at regular
intervals. Site based engineers.
Air and water
filters
• Calibrate, test and check
controls and operation. Excool
engineers every six months.
Controls
• Can be flushed. Normal
operation results in washing due
to adiabatic process.
Plate heat
exchangers
• Sealed for life bearings may
require changing every 5-10
years. Modbus interface
allows the temperature and
input power to be monitored.
Fans &
Motors
MAINTENANCE

22. • Reduced Capex
• Reduced Opex
• Reduced Maintenance
• Reduced Infrastructure costs
• Reduced Build Costs
Lower Total
Cost of
Ownership
(TCO)
• Increase in available IT power
• Improved resilience
• Faster ROI – de-centralised
system
• No Contamination Risk
Operational
Improvements
CONCLUSIONS