Not so long ago, availability was the driver for data center design. Solutions to this challenge have developed, and while it is still a critical goal, an additional driver has emerged: energy efficient design. Optimizing power usage effectiveness (PUE™) is dominating the current conversation.

You can determine your PUE™ by dividing your data center’s total power use – accounting for power used by mechanical systems and lighting as well as servers – by the server power use. Your PUE™ provides a metric to assess the efficiency of the overall infrastructure, and it can be used to demonstrate the effectiveness of any Energy Efficiency Measures (EEMs) that you implement. The goal is to get your PUE™ as low and as close to 1.0 as possible.

How can you achieve that? There are a variety of mechanical and electrical engineering solutions that can increase energy efficiency:

1. Use your environment. If possible, locate your data center in a region with mild temperatures and low humidity where you can use outside air for free cooling. Indirect evaporative cooling solutions offer the benefit of efficient evaporative cooling using outdoor air while eliminating the contamination issues associated with bringing large volumes of air into the server environment.
2. Raise the temperature. The industry preferred 72°F return air temperature control is quickly becoming a legacy, as many data center operators are raising temperatures as high as 77°F or higher at the server intake to save energy costs. One of our recent designs utilizes 80°F supply air to servers in combination with variable speed motors and hot aisle containment for a large data center. This offers higher equipment efficiencies and a greater number of free cooling hours.
3. Get creative. If your operations dictate a lower temperature, work with your mechanical engineer to customize a cooling system that meets your needs. GHT’s clients have experienced high efficiencies through a mix of indirect and direct evaporative cooling; hot and cold aisle containment; and close coupled fan systems (in-row or above-row cooling).
4. Enhance existing infrastructure. Retrofitting systems with variable frequency drives and ECM motors can increase cooling efficiency. So can remediating raised floors to eliminate bypass airflow. By minimizing unnecessary openings in the raised floor, you can improve the delivery of conditioned air to the servers.
5. Re-think your power scheme. Considerations to increase data center efficiency on the electrical side include deploying 400 volt UPS systems – thereby eliminating the losses associated with PDUs – and specifying efficient UPS models. Some manufacturers offer UPS products with a green or eco mode that can achieve 99% efficiency.

The push for energy efficiency in the data center industry is challenging MEP engineers and manufacturers to innovate constantly. The ideas above represent only a portion of the strategies that are delivering results for owners and operators. Tell us what else you’ve done to lower your PUE™ in the comments below.