On the right track to the sustainability finish line
Tue 12 Apr 2016
Energy efficiency is not just about reducing facility bills, it also plays a role in reducing environmental impact and improving sustainability.
Data centres of the past
The data centre industry has experienced rapid growth over the last couple of decades, and with it so too has its energy consumption. In response to rising energy costs, power usage effectiveness (PUE) was created to help owners and operators rationalise this consumption. It has, however, had both a positive and negative effect on the industry. PUE has, in very simple terms, helped make energy efficiency a high profile subject and has paved the way to a growing understanding of the industry’s impact on the environment.
However, it is used frequently as a proxy for sustainability. Sustainability and the green economy are about growing in a way that improves energy and resource efficiency, and reducing emissions and impact on the environment. Energy efficiency is only part of sustainability and therefore should not be considered in such an isolated manner. PUE has got the industry out of the starting blocks but until a more holistic approach is employed, sustainability is a long way off.
Walk before you run
The industry understands that the energy consumption in operation needs to be reduced, but there is still a long way to go to eliminate wastage.
PUE has a well-documented list of shortfalls, not least that it is frequently incorrectly calculated. Currently there is a lot of discussion about sustainable data centres, but cutting through the green wash to understand whether savings are being made can be difficult. ‘Green’ technologies are often designed into new builds and retrofits, but their operation needs to be in line with the design intent for these operational savings to be realised.
Data centres need to walk before they can run, and often little or no effort is made to manage air flows in the facility. For example, much energy is wasted when air from CRAH (computer room air-handling) units bypasses the IT equipment, returning directly to the air handler without cooling any equipment.
This wastage of supplied air means that servers draw hot exhaust air (recirculation) to fulfil their required airflow volumes. IT inlet temperatures rise as a consequence, and CRAH setpoints are often reduced to compensate. The result is higher energy consumption and inefficiency. Appropriate air management minimises this bypass and recirculation, enabling an environment optimised to allow for the potential raising of set points and lowering of fan speeds. Risk has also been lowered – IT equipment inlet temperatures are managed and controlled within an appropriate range with hot spots eliminated.
Operating at higher temperatures through air management and exploiting wider operating ranges for IT equipment (defined by ASHRAE in conjunction with hardware manufacturers) increases opportunities for using free cooling technologies. In many locations, particularly in the UK, it is possible to design and operate zero-refrigeration solutions.
There are often missed opportunities for energy efficiency due to a lack of awareness of the issues and poor communication between different stakeholders. For example, coordination between IT and facilities teams to optimise air delivery and operational parameters. The EU Code of Conduct for Data Centre Energy Efficiency provides a list of best practices that can be used to help make improvements in all areas of the data centre.
A holistic approach
A focus on operational energy efficiency is likely to continue, but for the industry to embrace sustainability it needs to understand that it is not a stand-alone matter. The industry needs to think of its consumption in terms of the energy and resources inputted throughout the entire life time of a facility – from the extraction of raw materials, through manufacturing, transportation, construction, operation and eventual end-of-life – and the resulting emissions to the environment. Using such a holistic approach will stop the use of ‘end-of-pipe’ solutions (such as PUE), which focus on one issue (energy consumption) or one life cycle stage (operation) and will ensure burden shifts don’t go unnoticed. Energy efficiency is incredibly important, but it should not be at the detriment of other areas of sustainability.
Publication of documents such as The Green Grid’s Data Centre Life Cycle Assessment Guidelines and inclusion of life cycle assessment in the Data Center Maturity Model show that key thinkers believe in this holistic approach, but there are very few mechanisms available to make it easily applicable. It is also time consuming to collect data and build models that consider a whole array of life cycle stages and issues. Research therefore needs to inform the industry to facilitate a broadening of concern. Current research, using a life cycle perspective, shows that beyond the operational efficiency of cooling, the industry needs to consider energy consumption of IT and cooling, the source of this energy, and the materials used to manufacture IT equipment, their refresh rates and the embodied impact of mechanical and electrical services.
There needs to be more attention paid to the 1 of PUE, not just the operating efficiency of cooling. IT equipment often operates with poor utilisation and high power consumption when idle. By considering these impacts we can begin to build and operate data centres that are more energy efficient and sustainable.
This article first appeared in Data Centre Management, Spring 2016