Didier Monestes – Stéphane Jaquet
A new energy efficiency methodology
for Datacenters

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A propos: initial impression
Presently, industries are one of the main energy consumers, be it in the domain of aeronautics or
specific industrial projects. Among these, datacenters are known for being particularly voracious.
Department of Civil and Environmental Engineering Professor at the University of Stamford, JG
Koomey is an internationally known specialist of datacenter electric consumption in the world. He has
explained that worldwide consumption has, on one hand, increased by 56% between 2005 and 2010
while on the other hand, represents the production equivalent of 30 nuclear plants, amounting to 6.5
million euro annually.
The following factors make a case for an efficient energy policy :
- in 2020 will reject as much carbon dioxide as all air traffic (Figaro Economie);
- the amount of digital information will multiply by 4 between now and 2016 (Cisco Global Cloud
annual study) ;
- around-the-clock availability of data is expected by all businesses and will become a
minimum requirement ;
- the cost of energy will increase without ceasing while diminishing the profits
Consequently, a structured and pertinent approach is essential in the framework of this type of
problem; this is what will be proposed in the rest of this article
A need for energy efficiency
As often seen, the standard approach is characterized by the involvement of IT Management and
General Management, who both have better energy efficiency for the datacenter as a common goal.
To check and predict the growing expenses, measures can be put in place to measure the relation of
the total electric consumption of the datacenter on the electric consumption of the IT production tool :
the energy efficiency, better known by the acronym PUE, for which a research value close to 1
represents optimal efficiency.
A PUE of 2 represents a system efficient at 50%, meaning it’s characterized by relative energy losses
equal to 50%.
An adapted engineering allows for the implementation of optimization tools of these ratios. In this
sense, the European Commission has published a best practice called « Code of Conduct for
Datacenters » which explains how to:
- calibrate the measuring system ;
- establish an energy efficiency fixture inventory for all facilities techniques
- relative to the datacenters (cooling, uninterruptable power systems,
- servers…) ;
- implement an energy efficiency plan of action.
The implementation of this « Code of Conduct » constitutes the best choice to reach this goal, in
particular with respect to the optimization of the PUE. The technical and operational Departments are
then responsible for the implementation of the related metrics and the research of a continued
improvement.
A need of method efficiency
A thought coming from a common experience of over 20 years of impartial and independent
Consulting, through major accounts in different countries, allows us to pick out the limits of the metrics
and of the « Code of Conduct ». One can be manipulated and can only serve as marketing
communication (PUE), the other often confronting governing and budget problems.

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The limits observed during the course of this type of project are reached when :
- the assignment of daily operational work often postpones to the next day the system
improvement logistics and overburdens the human resources;
- the facilities operational budget (cooling, electricity, etc.) is not connected to the IT
Department;
- the energy operational costs are not charged to IT Department users.
The necessity to adapt the « classic model » to specific company problems led us to implement
guidance allowing to align the management, budget usage and efficient project advancement in the
energy efficiency Department.
An efficient method that allows for a return on the investment
The method implemented by Didier Monestes and Stephane Jaquet depends on the General
Management with, as the main objective, a global strategy of energy efficiency for the company. It
rests on the ISO 50001 certification, which engenders a quality approach to energy efficiency based
on continued improvement. The responsibility therefore rests on the Quality Division/Department
which implements the energy efficiency audit throughout all Departments across all work processes,
with the help of dedicated human resources. This original Quality management does not create
additional expense for the company, but indeed a return on the investment in the operating cost, by
planned continual improvements.
IT Management can then rely on the datacenter « Code of Conduct » and request of/from the
operational Departments the implementation of the metrics and improvement solutions, led by the
Quality Department/division.
Pragmatically speaking, all the technical support of the datacenter infrastructure is reviewed
to obtain the best efficiency report for each component of the system and for its connections.
Here are some points that can be explored in this way:
Cooling techniques
The cost of cooling a datacenter is often the biggest. The knowledge of the design and the utilization
of free cooling are often utilized to optimize and check cooling efficiency. Emerging techniques are
regularly proposed. The Uptime Institute recently identified the utilization of a rack filled with a non-
conductor and re-cooling liquid that dissipates heat. This technique considerably reduces energy
consumption but must be adapted to the needs and constraints in any cases. Equally, the server
manufacturers have revolutionized the blade-type servers with new concepts allowing energy savings
of up to 80%. This new architecture supports 45 servers with 4U slots, each which integrates their own
components for cooling and supply, meaning five ventilators placed behind the bay, the entirety for
consumption per server of only 17 to 20 watts.
Electrical techniques
The usage of inverters guarantees the availability of the datacenters, and offsets the startup time of
the generators. This type of resilience requires a large electric resource of the city current. This energy
provided depreciates in fact by the piling up of techniques; the useful electricity flow is diminished by
reactive energy. This represents energy lost but already paid for. An analysis of the usage of this
energy allows for measuring, checking and then offsetting the losses of reactive energy.
To avoid electrical losses and bad quality of alternating current, a trend is raising in adopting a full
direct current from the Data Centre entry to the rack. A specific design and specification will be the key
for the best energy efficiency in this case.
Storage techniques
Usage of the SSD disc, composed of « passive » electronic components, greatly reduces the electric
consumption of these elements. The flash memory creates more fluid access to the data (0,1 ms
versus 13 ms on average). The servers are thus more reactive. The impact of this advantage is
directly in terms of the processor usage time.

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This technology considerably diminishes the problem of wear and tear/erosion. The electronic
components get used less easily than the mechanical components. What’s more, the wear and tear of
an SSD disc only affects its recording capacity and the viewing of its content, and it consumes much
less energy due to the absence of mechanical movements. Thus SSD discs consume less, are quiet,
do not give off heat and reduce the work of the processor.
Eco-conception software techniques
To answer the demands linked to durable/long term development (social / economic / environmental,
either « meeting the needs of present generations without understanding the capacity of future
generations to respond to theirs » - Bruntdland Commission), effort must also be made at the level of
software layer of the applications : that’s the set objective by the eco-conception software which
establishes a response to the transition of the energy source/resource towards a source/resource that
is no longer infinite for applications. In this regard, the ISO normalization system is in the process of
developing a reference document within 2 to 3 years maximum.
In the meantime, numerous initiatives are in progress, in particular the eco-conception web or the
development of new optimized programming languages (green patterns), where spectacular results
have already been obtained (Facebook, Yahoo!) Incidentally the Forester Consulting Firm has defined
3 distinct but complementary optimization categories with the designation Green IT 1.0, 1.5 and 2.0
(from « Green for IT » to « IT for Green »), measures potentially applicable to all companies.
Undoubtedly this domain already allows for a major optimization with its environmental footprint and
will be one of the biggest challenges in the coming years.
Supervision techniques
At the heart of the thought relative to energy optimization, the acronym DCIM (Datacenter
Infrastructure Management) takes on more importance : the Gartner Group recently announced that
the rate of penetration of this type of solution, presently at 1% of the DC, will be at 60% 2 years from
now.
Beyond these figures mentioned, the DCIM poses a basic question to know the implementation of a
common vision between the « facilities » (general services) and IT in the research of energy efficiency
optimization, and the availability relative to the data center.
The management of datacenter energy consumption allows to make a better match of infrastructure
resources and to defer the expense/cost of useless upgrades. This can also help the balance of the
electric phases and thus a better control/management of costs.
An adapted global response
By way of synthesis, the implementation of energy efficiency in a datacenter is a complex project,
which unifies a collection of independent expertises/experts which have, as their main objective, being
an available support, flexible and efficient for IT production. Only a systemic approach, a holistic view
and the implementation of a team of coordinated experts will set up the start of efficient actions in the
field. This is expressed by the alignment of processes according to operational standards (TIA942),
the monitoring of best practices by IT Management (« Code of Conduct ») and continued improvement
via the implementation of processes according to ISO 50001, orchestrated by the Quality Department
and prescribed by General Management (Cf. schema).
Stephane Jaquet and Didier Monestes propose the accepted/customary alignment by level of
administration and wanting the sole entry point of the coordination of this consulting for a better
efficiency of result : an energy efficiency that is measured, verified, well organized and carried out in
the framework of continued improvement of the company.
Stephane Jaquet
stephane.jaquet@dcc-consulting.ch
Managing Director
DCC Consulting
Didier Monestes
didier.monestes@sy-an.com
Managing Director
SYstemic Area Network