Ten steps to achieve better data centre energy efficiency

Improving data centre energy efficiency doesn’t involve overhauling the facility and the equipment hosted within. Taking small steps in energy management can lower costs.

Strategic energy management can bring data centre energy efficiency up and power costs down, and it’s not all that difficult a process. In this tip, data centre energy expert Clive Longbottom outlines approaches to help you make your organisation’s data centre more energy efficient.

Applying these ten simple steps can yield high returns for an IT organisation:

Rationalise, consolidate and virtualise. If your data centre is running at less than 50% server workload utilisation, then a large proportion of your energy is being wasted. Average server workload utilisation rates among enterprises are 15% or less. This means the remaining 85% of an enterprise’s server’s potential output is wasted. But, at the same time, the server uses a lot more than 15% of the energy and therefore releases more than 15% of heat. Driving up overall usage rates will improve energy metrics -- not just at the server itself, but all across the data centre as well. Because of the thermal and transmission losses involved, for every watt of energy saved, up to 4 watts can be saved at the point of generation.

Review the data centre operating temperature. If the existing operating temperature of your computer room air conditioning (CRAC) unit is in the low 20 degrees Celsius/70 degrees Fahrenheit range, then you are likely running your data centre too cool. Try moving the CRAC set point upwards towards 24 degrees C/75 degrees F -- or even higher if the majority of your IT equipment is relatively new. Each increased degree in temperature requires less cooling, so less energy is needed. Here’s how you can optimise CRAC units for data centre energy efficiency.

Use air cooling effectively. If you are cooling down the whole of the data centre, then there is a massive volume of air that is being cooled for no reason. Use hot aisle/cold aisle approaches, in-row cooling or other containment strategies to minimise the amount of cool air required and ensure that it is ducted effectively to cool down any hot spots.

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Don’t dismiss water cooling. Water conducts heat far better than air, so water is much more efficient as a cooling medium. Newer systems, based on negative pressure water systems, have extremely low failure rates and can dramatically lower cooling and, hence, energy costs.

Optimise energy distribution systems. For every voltage transformation involved in a distribution system, there is a loss of energy. Therefore, maintain a “flat” distribution system. The trick is to move substation AC voltages through data centre AC and DC voltages as fast as possible and route from there. Although only small percentages are involved here, saving even 1% of a large data centre’s energy bill can be worthwhile.

Consider the size of your data centre. If your existing data centre is large, think about generating your own power directly, particularly if the data centre is close to other businesses or housing developments. Excess electricity and heat can be sold into the local community, offsetting the cost of the energy generation. Overall energy efficiency can rise from around 30% to 40% to 80%+ through the use of community combined heat and power (CCHP) generators as opposed to centralised fossil fuel generators. The Digest of UK Energy Statistics comes out with an overall energy efficiency of 38.5%.

How big will your data centre grow in the future? If you think your data centre’s energy requirements are likely to increase in the foreseeable future, then self-generation could make sense, even if the data centre is only midsize now. With energy costs so variable, attempting to hedge costs now makes sense. Also, if you have a lot of excess power to sell, putting this back into the grid can be useful feed-in tariff revenues. However, if you believe that your data centre will remain the same size or shrink -- if, for instance, you adopt cloud computing -- then self-generation may not make as much financial sense.

Carefully choose a site for a data centre. If you have no choice as to the location of your data centre (as is the case in an existing facility), you should keep thinking about ways to save energy. If a new-build facility is on the horizon, consider building it close to a more sustainable energy source (such as hydro or geothermal) to make your data centre more energy sustainable -- even when no money is saved. However, if the placement of the data centre is completely flexible, moving it to a colder climate where you can use free air or free water economizers not only provides a more sustainable system, but lowers energy costs as well.

Use renewable energy sources. Probably not practical as a direct replacement for operating the entire data centre, but as an incremental source of power, renewable sources should be considered. Wind or solar energy is not predictable enough in most cases to provide core power requirements, but you can use it to deal with high energy costs during peak workloads by using feed-in tariffs. Energy created while the wind blows or when the sun shines is sold into the grid; energy required to deal with peaks is either drawn directly from the wind or solar systems if available, or purchased at spot pricing if the systems cannot supply it.

Don’t forget outsourcing. Not only does outsourcing cut costs from your organisation’s energy bill, it moves it to someone else’s, and as such may sidestep certain carbon emission taxes. An outsourced environment, however, may be far more efficient than your own. Use of a colocation data centre facility, a managed hosting provider, or even the cloud can ease energy demands across your total data centre infrastructure. It can also push up utilisation rates through the use of a highly engineered, multi-tenanted environment.

The data centre’s energy efficiency will remain a focus for most data centre managers. Taking steps to be more energy efficient -- and to have a more sustainable data centre -- does not necessarily mean massive changes to the facility and the equipment housed within it.

For effective energy management, IT pros can take these small, strategic steps to yield high levels of payback through cost savings and meeting their corporate social responsibility (CSR) targets. 

Clive Longbottom is a service director at UK analyst Quocirca Ltd. and a contributor toSearchVirtualDataCentre.co.UK.

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