Data Centre Energy Efficiency

Kit Leung
The energy use and environmental impact of data centres have become a significant issue for Hong Kong's operators and policy makers.

The data centre industry continues to thrive in Hong Kong, underpinned by reliable telecoms infrastructure and power supply, a strong reputation for data privacy and information security, readily available professionals and government support. Proximity to mainland China, but unaffected by China's data firewall and problematic prohibited zones, is another plus for the Hong Kong market, attracting inward investors looking to expand into Asia Pacific markets.

Both co-location and corporate in-house participants in the market have a range of issues to consider: operating efficiency, capacity planning, reliability, security, and performance management. With energy representing a sizeable proportion of data centre costs, a successful data centre strategy uses industry standard metrics to gauge and optimise server energy efficiency to meet changing customer requirements.

The popular Power Usage Effectiveness (PUE) metric was introduced by the Green Grid, an association of IT professionals focused on raising data centre energy efficiency. PUE is calculated by dividing the facility's total power consumption by the power consumed by the IT equipment. This calculation gives a ratio representing the effective power overhead for a unit of IT load.

The data centre industry continues to thrive in Hong Kong, underpinned by reliable telecoms infrastructure and power supply...

A data centre with a high PUE is seen as inefficient, as a significant portion of energy usage goes into powering the facilities rather than the IT equipment. Conversely, a data centre with a low PUE uses most of its energy to power IT equipment.

However, PUE is often criticised as the calculations are frequently misrepresented, failing to take into account the utilisation of the data centre, the efficiency of the IT equipment, and the climate factors. From time to time, colocation providers would publicise their energy PUE efficiency at full load when the facility is actually running at a higher PUE under partial load conditions for the majority of their life span.

These shortcomings have led to the creation of other metrics, but PUE's simplicity means that it's still the most widely used. Change is now afoot, spearheaded by the January 2016 third public review of the ASHRAE Energy Standard for Data Centres (90.4P). ASHRAE's review replaces PUE with two new efficiency metrics – Mechanical Load Component (MLC) and Electrical Loss Component (ELC).

MLC is the ratio of total mechanical load, to IT equipment load which only calculates the cooling system efficiency, similar to how "cooling only PUE" would be calculated. ELC is a calculation based on the losses of incoming service segment, Uninterruptable Power Supply (UPS) and IT equipment distribution. The new metrics should give data centre operators more flexibility in achieving energy efficiency standards.

The new metrics should give data centre operators more flexibility in achieving energy efficiency standards.

Ideally, the use of metrics would be part of a comprehensive energy management programme, which considers both the IT and the facility. In our work with clients, application of Data Centre Infrastructure Management, front flow cooling, free cooling, variable-speed oil-free centrifugal chillers and in-rack cooling have been helpful in achieving a more energy efficient data centre.

Faithful+Gould leads a wide variety of projects in the highly specialised data centre market, here in Hong Kong and across Asia Pacific. We work alongside developers, financial institutions and other corporate clients, government bodies and telecoms organisations, delivering their portfolio of data centre facilities. Our team of experienced and technically competent project managers have an excellent understanding of how data centres operate and how to create bespoke optimal facilities. Our services typically include due diligence, strategic advice at inception, management of both capital and lifetime/operating costs, construction management and testing and commissioning.