Beth Whitehead, Sustainability Engineer at OI, describes how the energy consumption, energy mix and number of servers provide the biggest opportunity for environmental impact savings in the data centre.
There is no denying that the data centre industry is acutely aware of the energy it consumes. Attend any conference or seminar or focus group, and you will find an emphasis is placed on improving energy efficiency. But is energy consumption the only demon in the data centre?
Metrics such as PUE are widely used by the industry, and their adoption has opened up the dialogue on environmental impact. But once a facility’s PUE is optimised where should attention be paid? Should the IT energy consumption or perhaps the embodied impact of the IT equipment be reduced? Or has the improvement in PUE resulted in an environmental impact in another area of the data centre?
These questions are hard to answer in isolation. Understanding trade-offs is incredibly complex, but to ensure the driving down of energy doesn’t result in pollution shift, environmental impact needs a more holistic approach that goes beyond just energy used to operate a facility.
Life Cycle Assessment (LCA)
Life cycle assessment considers the energy and raw materials used at every stage of a product’s supply chain, and the emissions that are created as a result of this consumption. The method studies this consumption and resulting emissions, from the moment materials are extracted, to the point the component is made, used and then disposed of at its end of life. Using cause-effect analysis, the contribution each emission has to a specific environmental impact – such as climate change, land use and carcinogens – is then quantified, much like the use of global warming potentials to compare refrigerants. By considering every component of the data centre together and beyond operation, environmental trade-offs can be quantified and managed.
For example, let’s consider just energy consumption and apply it to servers. Server inlet temperatures are raised to enable a reduction in operational cooling energy. These higher temperatures can increase server fan energy, minimising the operational savings from reducing cooling loads. However, if the server could be increased from 1U to 2U to allow better flow of air across the equipment, there would be additional energy used to manufacture the server (bigger chassis), but a potential saving in this additional fan power. By using LCA, the subtleties in this example can be quantified and total lifetime energy consumption (and other environmental impacts) minimised.
LCA is not a new concept. It has existed since the 1960s when Coca-Cola used it to understand the environmental implications of changing from glass to plastic bottles. Today it is used extensively by the chemical and construction materials industries, and there are signs that the data centre industry is joining the revolution. Perhaps the most significant sign is the release of a whitepaper on the topic by The Green Grid, the suggestion that it should eventually be included in the Data Center Maturity Model, the emergence of ICT studies that look at embodied (the impact pre- and post-operation) and operational carbon, and the creation of the Electronics Disposal Efficiency (EDE) metric which monitors the impact of electronic equipment disposal.
The Biggest Offenders – Energy, Energy Mix and Server Numbers
Results from a recent research project run by HP and London South Bank University (LSBU) yielded some interesting outcomes with respect to the life cycle environmental impact of data centres.
Graph 1 shows that the source of impact in the data centre is dependent on the type of environmental impact under consideration. For example, the impact from climate change and fossil fuels is most significant during the operational phase of a facility. The greatest opportunity to reduce a data centre’s contribution to these impacts is therefore by improving the efficiency with which IT and power and cooling infrastructures consume energy. When considering the impact from carcinogens, however, the impact embodied in the facility is almost equal to the operational impact. To reduce this impact, efforts therefore need to be applied across the lifetime of the facility. Environmental load is therefore not derived only from operating the data centre.
Graph 1 – Share of impact from the studied data centre for various environmental impact
Data centres can be incredibly different in their design and it’s clear that environmental impact varies, dependent on the systems used:
1. The baseline data centre studied used free cooling, was based in the UK , replaced servers every three years, and was fully populated with servers that used 50% of peak power to idle and were 30% utilised. This resulted in an operational impact 4 times the size of the embodied.
Figure 1 – Baseline case
2. When the same baseline facility was modelled in Sweden, with a server refresh of every year and an improved energy consumption from measures such as consolidation and virtualisation and reduced idle power, the embodied impact was almost double the embodied.
Figure 2 – Swedish energy, reduced energy consumption and increased servers
3. When the above scenario was studied in the UK and not Sweden, the embodied and operational impacts were almost equal in relevance.
Figure 3 – Baseline case with reduced energy consumption and increased servers
These aren’t radical scenarios, they represent facilities where every effort has been made to improve energy efficiency, and which include rapid refreshing of IT. These scenarios help to show three main areas within the data centre that currently offer sizeable opportunity to reduce environmental impact. These are the energy consumed in operation by the IT equipment, for cooling and in power losses; the mix of the energy used to produce the electricity (as presented in graph 2) and, importantly, the levels of IT equipment used across a facility’s life time.
Graph 2 – CO2 (g) per KWh in 2009 (electricity only) per EU member country
The Next Step in Reducing Environmental Impact
With the main areas of significance established, it’s tempting to focus solely on these topics. This is a good tactic for the current state of play, but to ensure any reduction doesn’t create an impact elsewhere, the continual monitoring of the total life cycle impact is important. LCA, however, is not for the faint hearted and requires endless attention to detail and time to compile studies. For it to be adopted the industry needs tools to lighten the workload.
The research project conducted at LSBU with HP included the development of a software tool that enables designers and operators to track environmental impact. Using the tool is simple, and requires quantities of the various materials, building services and IT equipment found in a specific data centre. The user is then provided with results on the environmental impact. The tool is incredibly important. For the first time, it makes it possible for designers and operators to understand the environmental trade-offs from different design choices for the building shell and all its contents, and omits the need for every user to be an expert in compiling complex environmental models.
With the tool comes the opportunity for the industry to benchmark its impact on the environment in a holistic manner, and creates the ground work from which a data centre rating system can be compiled.
The Human Element
Often the industry is considered in isolation, and in the spirit of using a more holistic approach, it can’t be ignored that currently efforts are made to reduce the symptoms (the impact from the data centre) without considering the cause (how the internet is used). We as consumers need to think about the way we use ICT as well – do we need to store photos online in various different locations? Do we need to stream the same YouTube video multiple times? Do we need to spend on average 35 hours a month online? There needs to be more education to ensure internet users understand there is a physical backbone to the internet, and their use of the internet has an environmental impact that is worth considering.
A Broadened Approach
Of the three opportunities for reducing environmental impact, energy mix of the country electricity supply is perhaps the most interesting. There are many difficulties in using renewables for a data centre, for instance the space required to implement on-site renewables and the lack of power if there is no wind or daylight. It’s therefore clear the industry needs to be creative in its approach to renewables – for instance by considering workload staggering – and importantly it must place pressure on the government to increase the renewables content of the energy mix.
While the industry has gone to great lengths to reduce its consumption of energy, there is a cogent argument for the need to assess and monitor more holistically the environmental impact of data centres
- The research discussed in this article was supported by the EPSRC, HP and LSBU. Beth Whitehead is a sustainability engineer with Operational Intelligence, who work with data centre operational teams to help them reduce their total cost of ownership
Originally published in Data Centre Dynamics Focus, May/June 2014 – http://content.yudu.com/Library/A2tmqx/FocusVolume3issue35/resources/index.htm?referrerUrl=