UNCOVERING THE LAYERS
the IT load. However, air movement,
even within a confined space, can be
chaotic. Many data centre designs now
incorporate the use of CFD (computational
fluid dynamics) to model the air
movement around the IT space. The
modelling is complex but greatly reduces
risk as it provides a detailed theoretical
model on how the technical space will
perform and react to dynamic loads.
Paul Finch, COO, Kao Data
a ‘flat PUE response’ from 25% to 100%
load drives up availability and uptime.
Demonstrating that low PUE, down to
1.2 to 1.0, is achievable, is not simply a
marketing tool, but a fiscal and ecological
responsibility for data centre operators.
Indirect Evaporative Cooling – IEC
In comparison to traditional chilled water
or refrigerant based systems, IEC is
relatively uncomplicated, although it still
requires mechanical ventilation in the
form of fans and heat exchanger with few
moving parts. Air heat-rejection occurs
when the return warm air is passively
cooled through contact with a plate that
has been evaporatively cooled on an
adjacent atmospheric side. A benefit is
that no moisture is added to the supply
side air stream as it returns to the data hall,
maintaining the humidity within the hall.
This ensures the precise supply air inlet
conditions can be delivered to support
IEC layout. Courtesy of FlaktGroup.
64
Issue 10
Modelling also assists in rack layout and
our results demonstrated that hot aisle
containment (HAC) systems, which stop
hot and cold air mixing in and around
the cabinets, offered the most efficient
design to allow controlled air-flow
circulation around the IT hall.
HAC draws cool air into the front of the
contained cabinets and through the IT
equipment and then expels hot air up and
out into the ceiling space to return to the
IEC system where the heat is rejected.
IEC, when
used
effectively,
allows data
centre
designers to
match the
environmental
conditions
in the data halls to the free-cooling
opportunity available within their
specific geography. This ensures that
evaporative cooling is effective for far
longer throughout the year.
The Kao Data IT hall
rack layout.
The latest IT equipment technologies
(servers, storage and networking
equipment) are developed to operate
within the parameters
characterised in non-
mechanical cooling
systems, such as IEC,
even with maximum
predicted annual
temperature excursions.
In many locations and
business strategies
the massive capital
cost of installing a
traditional chilled water
and refrigerant based
systems can be avoided.
Conclusion
The data centre market has become
increasingly competitive, as the industry
continues to expand into new regions
and that growth consumes increasing
amounts of energy.
Economic, public, as well as political and
social pressures, demand more efficiency
from the industry and energy is a large
component in the data centre cost
structure and a key focus from external
policy makers.
Developments in cooling technology and
the correct application of techniques
offers a transparent path to designing and
implementing non-mechanical cooling
strategies. These reduce complexity,
increase reliability and maximise the
operational hours of minimal cost cooling.
The correct application of the ASHRAE
environmental classes and broader
thermal guidelines will drive PUE lower,
not only at peak load, but consistently
deliver sub 1.2 PUE resulting in a far lesser
impact from a sustainability perspective.
Our industry is no longer reliant on feeling
our way forward to reduced energy use.
We have standard processes that provide
scientific support to more efficient and
effective data centre businesses. ◊
DELIVERING
LOWER
SERVER INLET
TEMPERATURES
USUALLY
REQUIRES LARGE,
COMPLEX,
EXPENSIVE
EQUIPMENT
AND COOLING
INFRASTRUCTURE.
www.intelligentdatacentres.com