Facility managers know if you can’t cool your computer room properly, you can’t run equipment properly. Even with server set point temperatures rising as equipment becomes sturdier and ASHRAE T9.9 standards now permitting up to 80.6 degrees Fahrenheit, there is always need for efficient airflow and cooling. Here we’ll explore why airflow management is important in computer rooms as well as common airflow problems and their solutions.
Why airflow efficiency is important in data centers
Up to 24% of a data center budget can go to cooling and nearly 40% of energy usage goes to cooling, according to an International Data Corporation survey and a Global Market Insights report, respectively. So first and foremost, keeping your cooling system as efficient as possible can have a major impact on the facility’s bottom line.
Furthermore, a computer room with a cooling system that is being managed inefficiently will have bypass airflow, meaning cold supply air is pumped into the room but doesn’t lead to productive cooling of the servers. The cold air passes the load, mixes with the warm room air and returns to the computer room air handler unit, or CRAH unit. That cold air is wasted, but the facility is still paying to produce it — and the CRAH unit is being put under unnecessary duress. When bypass airflow is minimized through airflow management, the CRAH units run with greater efficiency. This leads to longer lifespans, greater reliability and ultimately cost and energy savings.
Finally, when cooling efficiency is improved through airflow management, facility managers can potentially bring more cabinets into the room — getting more server capacity out of the same square footage. In short, airflow management can make a considerable impact on energy spending, equipment reliability and room capacity.
Common cooling problems that require airflow management
These are the key indicators that cooling efficiency should be examined in your facility:
- Environmental monitoring system (EMS) and temperature sensors indicate hotspots
- Difference greater than five degrees between warmest and coldest cabinet intake temperatures.
Additionally, here are metrics you can use to calculate various elements of data center cooling efficiency. These should be used as supplemental guides to the measurements in your room, but provide helpful figures to measure cooling efficiency over time.
- Calculate your Power Usage Effectiveness (PUE)
- Total Facility Energy / IT Equipment Energy, or use this calculator.
- A PUE greater than 2.0 shows opportunity for improved energy efficiency.
- Calculate your Cooling Capacity Factor (CCF)
- Total rated cooling capacity in kW / 110% IT critical load in kW.
- A CCF greater than 1.2 shows opportunity for improved cooling capacity.
If your computer room shows any indicators or doesn’t meet desired ranges for the metrics, you should take steps to employ airflow management in your facility.
Airflow management solutions
Simply put, maximum energy and cooling efficiency can only be achieved by proper airflow management. One of the most reliable solutions is containment, which is the use of soft or hard partitions to separate cold supply air from hot return air within a computer room. Various material options can be deployed during a containment install, and the end result is a fully contained aisle.
- Doors are installed at the ends of aisles.
- Containment panels are installed in place of missing cabinets and above cabinets.
One important consideration is whether to use hot aisle containment or cold aisle containment. There are scenarios in which one is preferred over the other. Your containment solution provider will take multiple elements of the room’s configuration into account (drop ceilings, raised flooring) to determine whether hot aisle containment or cold aisle containment is preferred. Additionally, when the kW per rack IT load is very high, both hot and cold aisle containment will be considered, though the resources to implement both is key.
In addition to containment, there are other supplemental airflow management products to improve cooling efficiency. There are multiple spots through the room where these products should be implemented, and each has a specifically engineered solution.
- To seal gaps in cabinets where there are no servers, use blanking panels.
- To seal gaps in between cabinets, use gap seals.
- To seal gaps from cable cutouts, use floor grommets.
- To stream more cold air into cold aisles from the subfloor plenum, use perforated tiles or high output floor grates.
- To efficiently draw hot air back into the CRAH unit, use hoods or chimneys.
How to implement airflow management solutions
It should be noted that airflow management can be approached in two ways. Facility managers can approach it gradually, adding in solutions in a piecemeal fashion as they plug holes and wait to see if the cooling efficiency problem is resolved with a few grommets or blanking panels. But the more effective method is to begin with complete containment. It’s the best way to handle heavy IT loads and ensure your room is operating at maximum cooling efficiency from the start.
Facility managers can implement these solutions on their own, but partnering with a data center expert is the most dependable way to approach airflow management. An experienced data center technician can analyze your room’s airflow data and cooling metrics and suggest the best containment and hot or cold aisle strategy based on your room’s configuration.
After reading through the best practices for cleaning efficiency, the next step is to evaluate your data center’s cleaning program. Download our guide to the Basics of Data Center Cleaning and Cooling Efficiency for a printable checklist to see where your program is excelling and areas in which you can improve your facility’s cleaning practices and stay tour-ready. Click here to download the guide.