Can You Cool 40kW per Rack?

Yes, 40kW per rack! Polargy’s Cold Aisle Containment was used at ViaWest’s recent Plano Grand Opening to demonstrate the site’s capability to cool high density deployments of up to 40kW per rack. Paul, with our partner USNet, led the installation of Polargy’s Rack Top Baffles and PX Doors. He is standing next to ComRent’s rack mount load banks which produced the 40kW load for each rack. Temperature sensors were placed through out the aisle. These showed that with the 6′ cold aisle on a raised floor and the open top containment design that the server inlet temperatures were properly maintained.

aisle containment door

PX Sliding Door

data center load banks

ComRent Variable Load Load Banks

data center temp sensor

Temp Sensors in Cold Aisle

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Rack Top Baffles at ViaWest

Cold Aisle Containment test

Test Cage at ViaWest

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Paul from USNet managed install

New Rack Top Baffle

Today, we are launching our new PolarPlex™ Rack Top Baffle. This is a new option for cabinet supported containment that provides a significant reduction in both the installation and material costs of deploying open top architectures. The new baffles, with their tool-less installation, offer flexibility and convenience for sites that reconfigure their layouts frequently due to moves, additions, and changes. The baffle’s modular design makes them an economical, quick-to-install solution that can be repurposed through the life of the data center.

I particularly like the Rack Top Baffles because they represent a new class of containment panels that are well-suited for projects where the ROI goals are extremely aggressive. With these baffles operators can achieve a compelling payback on their energy savings projects.PolarPlex RTB at 90 1

RTB on RACKs

One neat feature that we added to the baffle is a “J-Hook” so that lower level “InFIll” panels can be added to fill gaps between racks. This feature is ideal for spaces where there are columns or missing racks. In this case, we use a wider 5′ or 6′ Rack Top Baffle. Our baffles are available is standard and custom sizes.

PolarPlex RTB with SPSCRTB SPS1

By the aisle or by the mile

aisle_mile_thumbPolargy’s differentiation among containment manufacturers and contractors arises from our breadth of experience and depth of client understanding.

We bring to every project, whether large or small, not just attention to detail, precision design and product innovation, but years of diverse project experiences that allow us to visualize smart solutions and execute a project plan cleanly.

Big standardized new builds don’t have some of the “wild card” variables that small customized implementations often do, and while it’s gratifying to publicize large scale new construction containment deployments for Fortune 100 clients, we also enjoy sharing stories of modest retrofit projects brought online seamlessly. Every project, no matter how small, involves learning the client’s pain so we can solve it.

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Whether you need just an aisle or literally a mile of airflow containment, Polargy is the call you make, because here’s what our clients say:

“The project went very well and we consider it a complete success, I wouldn’t change a thing. The outcome was exactly what we expected.”


Suffolk Public Schools in Virginia called Polargy when the air conditioning units in their ‘server room’ were over-tasked. The ‘server room’ at Suffolk was never designed for this use, it’s actually a converted storage room with 20 tons of A/C. Common but not ideal.

Director of Technology John Littlefield used rack heat extractors (photos below) but Trane HVAC engineers recommended containing the hot air and recooling it.

suffolk_schools_4_smallsuffolk_schools_5_smallThe goal of the containment project was typical: eliminate the rack heat extractors and improve the energy efficiency of the server room cooling. Littleton contacted Polargy and accomplished his goal quickly with a modest budget.

suffolk_schools_1_smallsuffolk_schools_2_smallSince Polargy completed this project, the server room temperature is more stable, the cooling system runs more efficiently with less impact on the rest of the building, and the next step is to add an aisle-end door. The Polargy single-sliding door will look great.

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Decoding New Fire Codes

new_nfpa_stds_thumbThere is some confusion in the marketplace regarding changing fire safety regulations and materials deployed in the data center as airflow containment. To help clear things up, I prepared a technical briefling titled “New NFPA Standards Explained” which I have been presenting at AFCOM regional meetings. For the benefit of the many people who may be suffering a bout of this confusion and missed my presentations, I’ve provided my slides.

new_nfpa_stdsIf you’re planning a containment project, whether retrofit or new construction, and want to be sure you’re interpreting fire codes correctly, give us a call. Polargy is the trusted partner in data center containment to get your job done right the first time, on time and on budget.

2014: Gratitude and a look ahead

PLG Holiday Logo blog thumbPLG Email HeaderDecember invites reflection on (and gratitude for) the past year’s fortunes, as well as plans for the coming year. 2014 was a great year for Polargy in part because we saw a number of our industry forecasts come to pass:

  • Containment is increasingly viewed by owners as necessary, and a best practice, so sales cycles are accelerating as adoption grows
  • Streamlined containment design and deployment in wholesale and co-location environments allows owners to respond to opportunities quickly and competitively
  • Modular, floor-mounted and quick-build integrated containment solutions are growing in popularity, particularly in new builds with phased occupancy
  • Growing demand for smart and reliable solutions like cold aisle pressure management and automation in legacy environments

During 2014, with a focus on proven customer needs and with eye toward the trends above, Polargy released:

Next year we look forward to introducing even more innovative containment solutions and sharing more thought leadership to help the data center containment market mature.

Until then, we’ll leave you with our sincere Thanks and Best Wishes for the remainder of 2014—and 2015.

Industry Perspective: N+1 Cooling On Paper Only

frostbyte_fan_tile_blogthumbN+1 redundancy is a system design best practice because equipment failure happens; we expect it and we plan around it. In the case of data center cooling, we expect a CRAC to go down at some point, and with an N+1 system design we have a spare CRAC to fall back on. A major problem with this aggregate view of cooling is risk of starving a cold aisle when changing the CRAC lineup or as a result of CRAC failure, and this risk is amplified with cold aisle containment. Fortunately, we can easily and cost-effectively manage this risk with ‘air-mover’ fan tiles in the cold aisles.

frostbyte_fan_tile_blog_imageTime and time again we hear operators talk about how changing the CRAC lineup causes cooling airflow problems. Most of these comments come from legacy sites, though we’ve also heard them from new data centers. Interestingly, many operators fail to connect the dots between this airflow problem and N+1 redundancy. Many operators have a particular CRAC unit they don’t dare turn off and yet they assume their spare CRAC unit gives them N+1 redundancy. In our experience, about a quarter of small-to-medium data centers suffer from this false assumption; their N+1 redundancy is on paper only.

The Balancing Act

I can’t tell you how often I’ve heard comments like, “We need to keep CRAC Unit #3 on all the time or the room overheats” or “When we take CRAC #6 down for maintenance we get hotspots on the north side.” These problems are indicative of typical airflow behavior in raised floor environments:

  • CFM into an aisle is highly dependent on under floor pressure and obstructions.
  • CFM into an aisle is largely driven by the closest CRAC (the ‘CRAC of Influence’).
  • Changing the CRAC lineup creates large swings in CFM delivered to an aisle.
  • Total air supply may be sufficient but local supply may not (the ‘Distribution Problem’).

With these understandings, one can easily see how a change in the CRAC lineup can cause under floor pressure to change enough to introduce significant risk of an adverse thermal event.

When we think of cooling sufficiency, thermal safety and preventing problems, it’s in terms of normal operating conditions and failure conditions, and both scenarios are highly dynamic. In normal operating conditions we deal with routine changes in cooling demand and supply throughout room while the CRAC lineup remains unchanged. In failure conditions, we deal with a large change in under floor pressure when one CRAC goes offline and a spare unit takes over.

In normal operating conditions, routine changes in airflow demand and supply create risk of falling out of balance and starving a cold aisle. Cooling demand varies at the rack level, aisle level and room level, and can fluctuate either quickly or slowly. For example, a researcher who kicks off a large computational job can quickly heat up one or more racks of number-crunching servers. Or an IT guy swaps a 10kW rack in where a 2kW rack had been, but forgets to mention it to the facilities crew. These changes in demand for cooling create a less obvious change in cooling supply. When cooling demand in one aisle increases, the change in air consumption will affect the supply available to adjacent aisles. Such demand and supply changes during normal operations affect under floor pressure and can result in an aisle with localized low pressure.

In failure conditions, loss of a CRAC unit and replacement with the N+1 redundant unit will cause a change in under floor pressure. Because cooling supply to an aisle is most influenced by the nearest CRAC, and depending on the specifics of the under floor situation, a change in CRACs can result in a low-pressure zone and under-supplied aisles. There may be sufficient cooling supply, but because of the Distribution Problem, there is localized low pressure and even aisle starvation. In this case, even if the N+1 redundant CRAC unit comes online as planned, the best we can say is that the site has only partial redundancy.

Fixing With Fans

Fortunately, achieving true N+1 redundancy and mitigating cooling failure risk we’ve described can easily be achieved with active fan tiles that locally modulate airflow. Raised floor fan tiles, such as the Frost-Byte™ Raised Floor Fan Tile, vary speed to deliver cold air to the aisle based on sensed temperature or pressure differential versus a target setpoint. With several of these “air-mover“ tiles in a contained cold aisle, the right amount of cold air is supplied to mitigate thermal risk from inevitable cooling demand and supply changes during both normal operations and failure conditions.

These active fan tiles are built with a matrix of high performance variable speed DC fans in an aluminum enclosure attached to a standard 60% raised floor tile. Commonly, a temperature sensor mounted on the face of server racks controls the fans. Alternatively, sensors that measure pressure differential between inside and outside the contained cold aisle control the fans. This fan tile architecture auto-balances the cold aisles, eliminating starvation risk and improving thermal safety.

Other Fan Tile Benefits

An alternative solution to balancing cooling demand and supply is simply to over-supply an aisle, but with today’s emphasis on energy efficiency, the days of oversupplying are largely over. In fact, energy efficiency is the major factor driving the adoption of aisle containment, though even with containment, we sometimes still see oversupply due to balancing challenges. With active fan tiles, these remaining oversupply scenarios can be reduced or eliminated, yielding the full efficiency promise of cold aisle containment.

Additionally, by auto-balancing with active fan tiles, operators achieve labor savings from the elimination of routine manual balancing. The days of walking the room and swapping out perforated tiles are over. Active fan tiles eliminate the need to analyze aisles with a balancing hood (aka: flow balometer) to ensure the CFM in the cold aisle more than matches the IT load in that aisle. Likewise, because conditions in the room and aisles are so dynamic, Computation Fluid Dynamics (CFD) analysis for balancing purposes becomes obsolete since CFD provides a historical ‘snapshot’ of airflow that may no longer be relevant.

Lastly, if active fan tiles are powered through a UPS, they can ensure greater uptime if cooling is completely lost. In a catastrophic cooling failure condition, the under floor plenum holds a cool air reservoir, though without air pressure or air flow. Fan tiles running on UPS backup can continue to deliver and circulate cold air from within this chilled plenum. Testing demonstrates that supply air temperature through the fan tiles remained steady for more than 10 minutes even with all CRACs off.

The benefits of auto-balancing and solving the Distribution Problem that active fan tiles provide allow operators to enjoy true N+1 redundancy. Fan tiles offer significant additional benefits in a data center with cold aisle containment: even greater energy savings, local balancing and thermal safety.

Frost-Byte raised floor fan tiles combined with Polargy’s cold aisle containment take data center energy efficiency and thermal safety to the next level.