Mark Silnes

Mark Silnes, Marketing Manager-Cooling, Emerson Network Power, Liebert Services, says:

Today’s data center managers must respond to the constant state of change in the IT industry and look at strategies for optimizing a data center through management and planning. One such strategy that can provide significant returns is developing a holistic approach to thermal management which leads to improved efficiency.

Energy efficiency has become a top concern because of the demand within nearly every organization for greater computing capacity, and the trend toward IT centralization has increased data center energy consumption significantly. With both energy consumption and costs on the rise, data center efficiency has been elevated to a strategy for reducing costs.

Based on a 600kW load, each percentage point in efficiency improvement translates into $6,000 in annual savings in operating expenses. Additionally, efficiency is viewed as a strategy to manage capacity (possibly saving capital costs) and promote environmental responsibility.

From grid to chip, the data center offers a number of possibilities for lowering energy usage, with the cooling system being an opportunity for significant improvement. In a typical data center, cooling accounts for 38 percent of total energy consumption. This means the cooling system is where the biggest efficiency impact can be made.

In this first article of a three-part series, you’ll learn how to take the first step toward realizing efficiency without compromising availability ultimately leading to major energy savings.

Cooling Assessment

A cooling assessment will reveal the information needed to understand your data center’s cooling performance and to make informed decisions on how to improve it. A professional cooling assessment will identify hot spots, air flow issues, and inefficiencies in existing room conditions. It can also identify practices that, when improved, will reduce energy consumption significantly.


A professional cooling assessment can identify hot spots, air flow issues and inefficiencies in existing room conditions. It can also help improve practices to reduce energy consumption significantly.

A cooling assessment is recommended when an organization experiences any of the following:

  • Higher-than-normal data center operating costs that limit your ability to invest in infrastructure improvements needed to support business objectives.
  • Sub-optimal energy efficiency based on the need to meet organizational or environmental guidelines or as identified through an efficiency assessment.
  • Previously identified data center hot spots that can lead to equipment failure and outages.
  • Limited or no additional cooling capacity as realized during an IT equipment deployment or other infrastructure changes.
  • Server consolidation and/or virtualization which requires up-to-date cooling data for better infrastructure change management.

Think of a cooling assessment as an investigative report into how effectively the data center’s critical equipment is being cooled. As part of a holistic approach to thermal management, this investigation will uncover information to help solve the challenges listed above.

The cooling assessment also provides a baseline for determining expansion solutions, optimizing rack or HVAC layouts, and identifying cooling failure scenarios. Having the data gathered during an assessment will help you move beyond break-fix mode by enabling better decision making and planning, and it will also give you specific information about return on investment (ROI) to justify spending.

Immediate and Future Benefits

Improving efficiency is one way to save money and increase capacity, but there are other benefits to using information from a professional cooling assessment such as the following:

Improved Performance, Availability and Capacity

Assessments will identify the location and cause(s) of hot spots, allowing them to be eliminated before they cause IT equipment failure that results in downtime. Hot spots are areas where the temperature of the air being drawn into the server or other data center equipment is above the recommended range.

The process of identifying inefficiencies often uncovers ways to optimize current cooling to unlock capacity you don’t know you have. For example, an assessment may show that abandoned cables have built up under a raised floor and are restricting airflow. This restriction can cause undesired low pressure areas or even completely channel supply air away from critical data center assets. Removing cables will ensure supply air is going where it should, in effect, increasing cooling capacity. Ultimately, improved capacity allows the cooling system to do the same amount of work with less energy being consumed.

An assessment can lead to gaining data center space as well. Emerson Network Power has seen data centers in which better cooling efficiency drove the recovery of raised floor space. In one case, 60 percent of the raised floor was recovered.

Greater Ability to Plan for the Future

Based on the current state of your data center cooling system, the professional who conducts the assessment can offer vital recommendations for data center expansion and optimization planning. Using a tool like computational fluid dynamics (CFD) modeling, provides reliable information to support expansion plans by simulating future data center space. It maps out opportunities for future growth, allowing you to see where heat can and cannot be added which helps you make decisions on where to place additional equipment.

For example, cooling improvements enable higher rack density, freeing up physical space. By increasing the rack density in a typical 5,000 square foot data center from an average of 5 kW to 12 kW, the number of server racks is slashed from 161 to 27, creating the potential for an 83 percent savings in data center space.

Cost Savings

Improvements made as a result of a cooling assessment produce significantly higher energy efficiency that reduces the utility bill. Increased efficiency may come in the form of higher cooling capacities for existing cooling units or in the form of less cooling being needed because of improved airflow. The improvements can allow deployment of additional IT equipment without increasing cooling costs or can let you turn some cooling units off.

A typical cooling assessment includes recommendations that can save data center managers at least 15 percent in cooling energy or approximately six percent of the total energy consumption. For a facility with a load of 1,543 kW and energy costs of $.08 per kilowatt hour, the annual energy costs would be $1,081,334. Implementing the findings of a cooling assessment could save this facility more than $64,880 a year.

Better ROI

If you upgrade cooling equipment without first getting a professional assessment, you miss the opportunity to achieve the best ROI from the new equipment. An assessment lets you see beyond the equipment to issues, that if remedied, will improve its performance, such as unlocking cooling capacity by improving under-floor airflow or changing the new equipment set points to more energy efficient settings.

For example, adding a ceiling return plenum improves the efficiency of a computer room air conditioning (CRAC) unit by returning higher temperature air to the CRAC unit. If the CRAC unit is still trying to control based on the return air with a lower temperature that existed before the plenum installation, much of the gains will be lost. Adding variable speed drives to the unit at this time could also multiply the savings.

The final step in a cooling assessment is developing a report with site survey data and detailed recommendations. The data provides quantifiable justification for making cooling system improvements or capital expenditures. Keep in mind that the typical practice of making cooling unit improvements one at a time misses the opportunity to optimize the cooling system. In turn, maximum efficiency benefits and operational savings are not realized. By taking a more holistic approach starting with a cooling assessment, system energy consumption can be reduced by up to 70 percent.

What if your cooling assessment uncovers inefficient airflow? Watch for part two of my series on options for addressing that issue.