ASHRAE Journal - June 2020 - 47

2020 ASHRAE TECHNOLOGY AWARD CASE STUDIES

Power Cost Per Year (£m)

12
10

£11.79m

Table 2 Carbon dioxide calculation based on Carbon Trust
conversion factors (2011), www.carbontrust.com.

Uptime Institute Survey of 500 Data Centers
(2014): Average PUE = 1.70 (£10.02m)
£10.61m

Customers' Power Cost
£8.26m Annual Saving: £2.95m
£7.01m
£6.49m
Kao Data

£9.43m

6
4
2
0

Simulated
Thermal IT
Load

PUE

Total
Power
(kW)

kW
Difference

Equivalent
(kgCO2)

100%
(2,200 kW)

1.21

2,662

462

242.4

As Compared to a Typical Data Center, Where the PUE is 1.58:
2.0

1.8

1.6

PUE

1.4

1.2

1.1

Analysis Based On:
* Operating 8,760 Hours Per Year
* 8,800 kW Campus Data Center Building At 85% Utilization
* £0.09 kwh Power Utility Cost
Industry typically represents PUE by considering data center performance at
the peak design or contracted kW load. Coincidently, this approach aligns
with the optimum operating efﬁciency of the power and cooling systems
supporting the data center. This can lead to exceptional PUE at 100% load.
However, in practice the data center kW load is dynamic, which has an
adverse effect on the efﬁciencies of both the power and cooling systems,
which have been optimized for 100% kW load. This impacts energyefﬁciency, resulting in a proportionally higher PUE at part load. At Kao
Data Campus, through innovative engineering, the PUE remains relatively
constant from 20% to 100% of the kW load, resulting in potential energy
savings against legacy solutions in the order of 25%-30% for the customer.

FIGURE 4 Average annual operating PUE. Notes: Uptime Institute survey data: 1.89 (2011),
1.80 (2012), 1.67 (2013), 1.70 (2014)

using refrigerant-based cooling, resulting in a higher
PUE.

Environmental Impact
The absence of refrigeration systems has minimized
the potential global-warming and ozone-depleting
impact on the environment, in addition to carbon
emissions.
To demonstrate this, Table 2 compares data for data
centers, with PUEs of - 1.21 (Kao Data), 1.58 (2018 industry average), and 2.0 (2011 industry average), in which
the PUE has been translated into an equivalent CO2
emission based on the Carbon Trust (2011) conversion
factors (www.carbontrust.com).
Notably, the Building Research Establishment
Environmental Assessment Method (BREEAM) uses
scientiﬁcally based sustainability metrics and indices
that cover a range of environmental issues. Its categories
evaluate energy and water use, health and well-being,
pollution, transport, materials, waste, ecology, and
management processes. In recognition of the minimized
environmental impact of the facility, Kao Data was
awarded a BREEAM rating and certiﬁcate of "Excellent"
for both the design and construction.

100%
(2,200 kW)

1.58

3,476

1276

669.4

As Compared to a De-Rated Data Center, Where the PUE is
2.0:
100%
(2,200 kW)

2.0

4,400

2200

1,154.1

Conclusion
It has been demonstrated that through innovative
application of appropriate technology and taking an
opportunity-risk based approach, the ASHRAE thermal guidelines can be maintained without the use of a
mechanical refrigeration plant.
The absence of a refrigeration plant introduces a range
of beneﬁts in the form of both energy efﬁciency and
sustainability, as well as longer-term OPEX savings for
both the data center customer and operator.
Through the omission of a mechanical refrigeration
plant, Kao Data Campus sets the standard for data
center design construction and operations, reducing
the environmental impact of data centers in a manner that also makes both commercial and economic
sense. In a growing data center industry, driven by
consumer demand for data services, the application
of appropriate technology and a considered design
approach provide a global opportunity for data center
owners and operators to bolster their corporate social
responsibility credentials, as we strive toward delivering the ultimate in sustainable software deﬁned
data centers.

References
1. ASHRAE. 2015. Thermal Guidelines for Data
Processing Environments, 4th Edition. Atlanta:
ASHRAE.
2. ASHRAE 2013. Particulate and Gaseous
Contamination in Datacom Environments, 2nd edition.
Atlanta: ASHRAE.
J U N E 2020

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ASHRAE Journal - June 2020

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