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Enhancing Performance with Computational Fluid Dynamics

Enhancing Performance with Computational Fluid Dynamics

Article Featured in Data Centre Review
By: Gordon Johnson, Senior CFD Manager, Subzero Engineering

The current and growing industry focus on sustainability has highlighted the need to work towards energy efficient data center designs, which, in turn, should provide the perfect combination of sustainable operating conditions. The end result being truly optimized data center performance.

Computational Fluid Dynamics (CFD) plays a vital role when it comes to data center construction, retrofit, and helping improve the efficiency and performance of legacy data centers. It allows the owner or operator to simulate endless combinations of racks, cabinets, cabling, and mechanical and engineering (M&E) equipment for greater optimization.

The owners and operators of these facilities may not be aware that they are literally blowing a lot of (unnecessary) cold air into the aisles in order to keep the servers, switches, routers, and the storage units cool. What they will know, however, is that this wasted air is wasted money. Worse still, emissions will be increased, hot spots will remain an issue, and they will eventually experience equipment failures.

Many data center managers know that something has to change to overcome this unsustainable situation, but they may not have a plan or strategy. This is where CFD is critical.

CFD is essentially an MRI of the data center, and when it comes to informed decision-making, the mantra ‘if you can’t measure it, you can’t manage it’ still holds strong. However, in the case of CFD, ‘if you can’t measure it, you can’t improve it’ may be more appropriate.

What is a CFD analysis?
CFD software creates a 3D model of the physical attributes within a data center, as well as the location and performance characteristics of the cooling units, IT equipment, power systems, and other significant components of the data center.

This ‘data center MRI’ provides a complete, detailed thermal understanding of the data center, providing insight relating to the physical layout of the space and equipment; the power equipment thermal dissipation and rack power density; environmental conditions; cooling capacity and air distribution effectiveness.  This is the baseline model or the “as is” snapshot of how the data center is currently operating.

From the information obtained, additional CFD modeling will recommend how to optimize the operating environment while reducing energy and maximizing efficiency.

Many key benefits of CFD analysis include assessment of the data center layout and its performance; validation of proposed design changes, considerations for efficiency and reliability; accurate prediction/simulation of the cooling design process; the ability to assess temperature and airflow modeling; and reconditions for a cost-effective and energy efficient design.

CFD provides clarity
A data center CFD analysis provides the visibility that is essential when it comes to understanding both your existing operating environment and any potential design changes. CFD can also be used to test out ‘what if’ scenarios when it comes to new data center construction or modernization projects.

In essence, a CFD provides detailed, data-driven analysis of the cold supply air and the hot exhaust air throughout the data center, and identifies the potential overheating of IT equipment “hot spots”. Such analysis highlights the way in which energy costs can be reduced by optimizing and maximizing data center cooling. CFD is a tool used to virtually test legacy (and new) data center environments for active temperature, pressure and airflow, and to optimize the mechanical system directly to server heat loads (kW).

Armed with data from the CFD analysis, a suitably experienced technology partner, such as Subzero Engineering, can advise customers on impactful data center design changes, upgrades, or tweaks to improve operating improvements – all of which will help optimize and reduce energy usage.

For example, CFD modeling can demonstrate what impact a cold aisle containment (CAC) system will have versus a hot aisle containment (HAC) system. It will advise which method will save more energy, full or partial containment. After containment is installed, it will show if computer room air conditioning (CRAC) units can be turned off and how low fan speeds can be reduced on computer room air handlers (CRAHs). Finally, it will also inform the user on how high the operating temperature can be increased, while following the recommended thermal guidelines from AHSRAE.

The end result is that CFD based design improvements will provide customers with significant PUE, WUE, KW, kWh, carbon, and water reductions.

A logical conclusion
One of the major benefits of using CFD modeling and analysis is that it can quickly demonstrate how a containment solution will immediately reduce a data center’s energy cost and lower its environmental footprint.

Regardless of which type of containment is used, large energy savings can be achieved by optimizing the airflow and raising the supply temperature, while simultaneously eliminating hotspots. Additionally, containment improves the benefits and economic feasibility of other efficiency measures, such as digital scroll compressors, electronic commutation (EC) and variable speed drives, data center infrastructure management (DCIM) software, and building controls.

Further, by separating the cold supply air from the hot exhaust air, containment saves energy, thus reducing operating costs. Yes, there is the initial investment cost of installing the containment solution, but the potential return on investment (ROI) of 10-14 months means that, very quickly, end-users will achieve payback. What’s more, from that point onwards, they’ll be saving energy, reducing operating expenditure (OpEX) money, and reducing carbon emissions to become more sustainable.

A savings summary
Since 2015, we’ve kept track of the various savings we have achieved for our customers through the careful, considered optimization of their data center environments. The numbers are impressive: our customers have saved just under 3.5 billion Kilowatt hours, reduced water consumption by one and a half billion gallons and have a total carbon reduction of over 3.2 million tons – the equivalent of planting 17 million trees.

Along the way, we’ve also been able to help customers achieve up to a 29% energy cost reduction, and been able to reduce PUE (Power Usage Effectiveness) by an average of 0.4 and WUE (Water Usage Effectiveness) by an average of 0.3.

Subzero Engineering believes that a data-driven approach to digital infrastructure is essential and thanks to the use of CFD, we can simultaneously help our customers increase data center density, operating efficiency, and environmental sustainability by implementing optimized containment solutions.

However you choose to address the challenge and opportunity of improving the efficiency of your data center, it’s essential that CFD is used as a key tool in this process. Without CFD, whether you choose to implement an optimization program yourself, or to engage with a technology partner, you’ll neither be able to understand how your data center is performing right now, nor what improvements can be made into the future.

CFDComputational Fluid Dynamicsdata centerData Center Containmnetdata center performance
5 Steps to Improving Data Center Performance & Energy Efficiency

5 Steps to Improving Data Center Performance & Energy Efficiency

By Sam Prudhomme, Vice President of Sales & Marketing

Recently, I was interviewed by a Computer Weekly journalist, Fleur Doidge, who was writing an article focusing on the quick wins when it comes to improving systems performance in the data center. Inspired by our discussion, I’ve come up with Subzero’s top 5 ways to boost data center utilization.

The data center industry, quite rightly, has an ongoing, major focus on how it can improve both the performance and energy efficiency of its facilities. That’s partly down to the perception that our industry are major consumers of energy and contribute a high volume of carbon emissions each year.

According to an article published in Science Magazine, data centers account for around 1% of global energy use. It’s clear that we need to improve our environmental performance and to ensure we never forget we’re part of the sustainability solution, but we should also remember that data center performance and energy efficiency improvements make great business sense.

While there are many, many issues to consider as part of a comprehensive, long-term strategy to both improve data center performance as well as to achieve carbon neutral status, this article focuses on the ‘low hanging fruit’ – relatively simple actions, which will have an immediate positive impact on your facility, and with an ROI measured in months rather than years.

Step 1 – As Easy as (free) CFD

Those of you who know Subzero Engineering well will not be surprised that Step 1 involves a Environmental Impact Evaluation (CFD) of your data center. We believe it all starts with the data and offer this service for free. It is a simple, efficient, and super-fast way of discovering just how your data center is performing right now – where the power is, where the heat is, and isn’t, hence where the cold air does or doesn’t need to be.

Step 2 – Using the Data

Once the Environmental Impact Evaluation (CFD) has been carried out, you’ll be armed with a large quantity of data about how your data center is performing. It’s highly likely that you’ll be presented with some really quick wins. For example, you’ll discover where the hotspots (points of efficiency leakage) are; and part of the solution may be something as simple as installing any necessary blanking panels.

Then again, the CFD data may highlight that Row 5 in Rack 6 is running 15 degrees hotter than anywhere else in the data center. You’ll be able to decide whether you need to move this stack to a better location where more cooling is available, or maybe you just need to open up the grate to optimize or increase the airflow.

Step 3 – The 3 ms: Measuring, monitoring & Modulation

A data center is a live environment. So, although the CFD analysis can identify and help to resolve what we might call any ‘permanent’ power and cooling issues, it’s essential that you monitor and measure the performance of the power and cooling plant in real-time. This is because data center variables such as the IT load and operating temperatures are in constant flux. With the right system you are able to modulate the airflow accordingly. For example, if the cooling needs to react to the load inside each rack and cabinet, as well as respond to the impact of, say, an extremely hot outside temperature.

Rather than blast a load of cold air into the data center and ‘hope’ that it keeps the IT hardware within operating tolerances, with the right monitoring solution, you can be confident that you can modulate the cold air as required right down to the rack level. This ensures that the cooling usage is as effective and energy efficient as possible.

Step 4 – Contain Your Excitement

How would you like to reduce your PUE by 0.4? Or to achieve a 29% reduction in data center energy consumption? Well, these are the average savings we achieve for our customers when they deploy one of our containment solutions.

The initial Environmental Impact Evaluation (CFD) we carry out also proves how this can be achieved – it compares and contrasts hot vs cold aisle containment and containment vs no containment. Furthermore, a containment solution ensures that Steps 1-3 really do achieve the maximum performance and energy efficiency improvements within the data center.

Without containment, you’ll still have hotspots – separating hot and cold air will be hit and miss and far from being optimized.

With containment, you can bring down the power consumption to cooling ratio close to a 1:1 match in KW consumed – that’s how the energy consumption/utility bill reduction is achieved.

As for the PUE reduction? Well, that’s achieved by smarter, more efficient use of an optimized combination of chilled water and the air conditioning fans. The US Environmental Protection Agency (EPA) estimates that containment can reduce fan energy consumption by up to 25% and deliver 20% savings at the cold water chiller.1

One final containment benefit – we supplied a containment solution to a colo customer and by separating the hot and cold air in their facility, we helped them to not only eliminate hotspots, but also to increase rack density by an average of 14%.

Step 5 – Turn the Lights out

This breadth of knowledge brings me to my final data center performance and energy efficiency improvement: turn out the lights. By that, I actually mean remove anything incandescent and go with an LED retrofit kit within your existing tray system. And then automate the lighting system.

It may be a while before a true lights out data center becomes the norm, if ever, but that’s no excuse not to ensure that your lighting system is as energy efficient as possible. By using LEDs and only using the lights when needed you’ll improve your energy efficiency as well as your bank balance.

While Subzero Engineering’s major focus is data center consultancy, using CFD analysis and containment solutions, to help drive performance and efficiency improvements we can also help owners/operators with their critical power infrastructure, DCIM and other solutions as required.

Download the 5 Steps to Improving Data Center Performance & Energy Efficiency pdf here.

 

References

1Recalibrating global data center energy-use estimates – Science Magazine 2018

CFDContainmentdata centerdata center energy consumptiondata center performanceEnergy EfficiencyEnvironmental Impact EvaluationPUErack densitysustainability