Application Story

Ferreting out energy savings opportunities in complex data centers can be a game of hide and seek. But Critical Systems Testing (CST) has found a way to win the advantage with a special 'Come out, come out, wherever you are tool' – Onset Computer Corporation's HOBO data logger, a small, portable device that uncovers a wide range of hard-to-find information.

CST is a Colorado-based reliability and energy efficiency company, which validates that automation systems are operating to equipment specifications in data centers, often during commissioning or retro-commissioning. This is an important task for many reasons, not the least of which is that data centers house the necessary equipment to keep America's Internet-driven economy up and running.

Moreover, data centers use a lot of energy – 10 to 30 times as much as the average office building, according to the Lawrence Berkeley National Laboratory. By some estimates worldwide emissions from data centers will quadruple by 2020.

How can data centers improve their energy efficiency? That's where Onset's HOBO ZW Series wireless data nodes come into play with their real-time detection of temperature, humidity, power consumption and other important measures. The wireless data nodes transmit data from various points in a data center facility to a central receiver connected to a computer. This eliminates the need to manually offload data from multiple individual data loggers.

In a typical data center testing application, data nodes are set up to form a scalable wireless sensor network, to which additional measurement points can be added over time. Leveraging self-healing network technology, the nodes can automatically route data to the receiver, despite obstructions, without manual intervention. Optional routers enable data hopping across rooms, partitions and floor levels, and each data node can be set up in dual mode – data logging and data routing – to provide further network flexibility.

Accompanying HOBOware® Pro software provides real-time graphs for each measurement point, alarm notifications, and a network map feature that provides an at-a-glance view of the wireless sensor network so each node can be easily located on the image of site floor plan.

"Data centers already undergo a test process more rigorous than that of a typical office building. These are mission critical applications so you have a higher level of testing," said Michael Rosenberg, CST Operations Manager. "Real-time data access is important. In a lot of instances we need real-time data to show us instantaneously what's going on and what the temperature conditions are during various testing scenarios. At the end of our commissioning process, we take it through a process called the IST (integrated systems test) and that's a full three to four day process where we look at electrical and mechanical systems and how they interact with each other."

Energy waste is not always apparent, given the complex relationship of systems within data centers. But wireless HOBO data nodes, placed strategically throughout the data center, reveal true operating conditions. For example, temperature readings may show areas of the system that are being overcooled beyond the system's design intent. Raising the temperature at these points can reduce the data center's energy use.

"Many data center systems already have temperature monitoring devices built into the complex automation systems that CST commissions. But the monitors often only measure temperature at fixed locations. Onset data loggers provide us the ability to measure conditions at locations that the instrumentation, built into the facility automation systems, will not provide," Rosenberg said.

The wireless sensor network facilitates this fine-tuning by collecting data from remote points without the need for running wires and cables.

Onset data nodes also may help CST reveal if control devices, such as dampers, valves and variable speed drives, are not operating properly, a problem that a data center manager may not be aware of. CST uses a variety of Onset's plug-in accessories such as carbon dioxide sensors, pressure transmitters and air velocity sensors, in addition to the logger's built-in temperature and humidity capabilities. These devices easily plug-in to the Onset's data nodes external inputs and can be used to evaluate several other operating conditions that can indicate a waste of energy. For instance, low CO2 level readings or high space pressures can indicate over-ventilation. Excessive air velocities coupled with low temperatures at equipment racks can also indicate wasteful air distribution.

"We can address component level deficiencies and re-engineer a control sequence to address performance related issues and improve energy efficiency," Rosenberg said.

With its fine-tuned approach to data collection, measurement and analysis, CST is able to serve clients above and beyond what the job calls for. Data nodes help CST uncover ways the automation system not only meets, but also can exceed design expectations.

"Often tweaks can be made, if the engineers want to optimize the system for energy efficiency. Optimizing energy can be analogous to an onion with multiple layers. Each process improvement can expose other deficiencies that must then be addressed. Coupling Onset's data nodes with facility automation systems helps us evaluate the facility operations from the load side all the way through the energy usage pipeline," Rosenberg said.

The CST testing system also provides valuable measurement for data centers – and any buildings with complex automation systems – during post-commissioning. Once a building is in operation, it is possible to uncover additional opportunities to improve its efficiency.

"A facility may achieve 70 percent of its energy efficiency potential at the completion of the formal commissioning process; the remaining 30 percent will be achieved through fine-tuning systems after the building is occupied and operational," Rosenberg said. "The ongoing process achieves the highest level of operational efficiencies in today's complex automation systems."

CST has been using data loggers for years, and is especially pleased with Onset's latest wireless technology.

"CST has been using these loggers since the earliest iteration. The wireless technology goes to the next logical step in technological evolution. It allows CST to show its clients data real-time during the commissioning process. It avoids the process of having to install loggers for a week, pull down the trend data to a spreadsheet and then analyze it. The wireless loggers provide much more flexibility. We can pull down data at any point and provide analysis of the process instantaneously to make control system adjustments. This flexibility provides a vastly improved process for commissioning and system analytics," he said.

Onset data loggers and wireless sensors will continue to play a major role for CST as its business grows. "The data logger is an important tool for us. We can supplement anything a building automation system can monitor with data loggers," he said.