ASHRAE Journal - June 2020 - 46

2020

ASHRAE TECHNOLOGY AWARD CASE STUDIES

Innovation
Through the innovative application of the thermal
guidelines, this facility is the only wholesale co-location data center within the UK to operate without the
requirement of mechanical refrigeration. The adoption of IEC technology has permitted reduced complexity in engineering design and services infrastructure, improving system reliability and availability.
During the design stage of the project, computational
ﬂuid dynamics (CFD) modeling was used as a tool to validate the concept of the cooling system, both internally
and externally, to verify that the internal conditions
would maintain weather conditions, without mechanical refrigeration (Figure 3).
Being able to test a prototype in the virtual environment not only enabled the efﬁciency and efﬁcacy of the
cooling system to be theoretically stress-tested and manage risk on a major capital investment, it also supported
other design disciplines. For example, assessing the heat
transfer across the ceiling allowed the architect to determine the speciﬁcation for the thermal performance of
the ceiling tiles.

Operation and Maintenance
The absence of refrigeration systems (compressors,
condensers, evaporators, expansion devices, controls,
and refrigerant medium and leaks) from the primary
cooling system has offered signiﬁcant operating expenditure (OPEX) beneﬁts. Additionally, this signiﬁcantly
improved service availability, as system complexity was
reduced and reliability increased due to the lower mean
time to repair (MTTR).
The modular nature of the IEC technology also meant
that the cooling system became distributed, reducing
the standing redundant capacity often seen with centralized systems, which can depress operational efﬁciency under part-load conditions.
Redundancy is provided in the primary cooling system
through N+1 capacity of the IEC and the process water
treatment plant; this ensures that maintenance can
occur during normal work hours and mitigates risk of
loss of system effectiveness.
From inception, the transition across every milestone
or stage of the building's life cycle was closely considered. Most relevantly, a soft landing approach was
adopted in which the operations team, who would subsequently take possession and operational responsibility
46

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J U N E 2020

Cooling Used (%)
96.6
95
93.5
91.9
90.3

Temperature (°C)
26.5
26.2
26
25.7
25.4

FIGURE 3 Screen shot from CFD modeling.

of the data center, joined the project team through all
construction and the commissioning phases of the project. This approach facilitated knowledge transfer and
enabled familiarization of systems in a non-live environment, which, in turn, resulted in a smooth handover of
the building.

Cost-Effectiveness
The project was delivered under budget and on schedule, in part due to the reduced complexity in engineering design. The omission of mechanical refrigeration
has eliminated part-load degradation of PUE, which
is of signiﬁcant importance within the economics of a
data center, where utilization in the co-location market
has historically varied between 50%-85% of maximum
design capacity. In December 2018, the publication,
Datacentre Dynamics, performed a supermicro survey
of 361 data center professionals, in which the average
PUE from respondents was 1.89, while 22% reported an
average PUE of 2.0 or higher.
The analysis in Figure 4 is based on a -8.8 MW
(30.0 MBtu/h) data center, comprised of four 2.2 MW
(7.5 MBtu/h) technology suites, 85% IT load utilization,
£0.09/kW power cost, 24/7/365 operation, and a term
of one year. Furthermore, total cost of ownership (TCO)
can be considered as total real estate cost per year +
power cost per year. As the total power cost correlates
directly to the PUE, and the omission of refrigeration equipment has reduced both capital expenditure
(CAPEX) and operational expenditure (OPEX), the
analysis in Figure 3 demonstrates that Kao Data will
yield a signiﬁcantly lower TCO for a comparable facility that maintains an internal technical environment
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ASHRAE Journal - June 2020

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