Improving energy efficiency in the data centre

“IT MADE SENSE AT THE TIME,” says Craig Watkins, product manager for rack and cooling solutions at Tripp Lite. The cost of powering a rack server during its operational lifespan can easily exceed the hardware cost of the server, so we don’t just consider the speed of the server anymore – we need to know how much speed we get for each watt that is consumed. Today, data centre managers need to keep a close eye on energy costs. According to the Uptime Institute’s 2013 Data Centre Survey, 61% of respondents, worldwide, said reducing energy use was “very” important, and 82% said the primary motivation was cost reduction.

While reducing power consumption in a data centre environment can seem like an arduous task, there are a few simple steps that you can take when it comes to cooling efficiency and the implementation of PDUs with remote monitoring capabilities that help will lead you to the energy and money savings that many are now looking for.

An Uptime Institute study found that up to 70% of data centre energy use is for cooling and air handling, so increasing cooling efficiency is vital to reducing costs. “It used to be that if your data centre felt uncomfortably cold, people were impressed. It was considered a sign that you were doing a good job keeping servers from overheating. Rack densities were lower, electricity was cheaper and nobody was paying attention to the electric bill” said Watkins. “Now that attitude has dramatically changed and if you start with the low-hanging fruit you’ll be surprised how much you can save with a few simple steps.”

1. Implement hot-aisle/Cold-aisle
“You don’t need to keep your data centre at meat locker temperatures,” states Watkins. “Instead, concentrate on removing hot air from the room before it recirculates.” Separating hot and cold air is the key to cooling efficiency. Start by arranging racks in rows so the fronts face each other in cold aisles and the backs face each other in hot aisles. That prevents servers from drawing in hot air from servers in the adjacent row. According to studies by TDI Data Centres, hot-aisle/cold-aisle configurations can reduce energy use up to 20%. Tripp Lite’s SmartRack™ enclosures are optimized for hot-aisle/cold-aisle.

2. Install blanking panels
When planning your data centre cooling strategy, the use of blanking panels in empty rack spaces can greatly improve rack cabinet cooling at a fraction of the cost of forced heat removal or supplemental air conditioning. Energy Star has included blanking panels as key devices for efficient airflow control in server rooms.
Rack enclosures are designed for front-to-rear airflow. Cool air flows through the perforated front door and cools your equipment, which exhausts warm air through the perforated rear doors. Airflow management prevents warm air from recirculating and contaminating cool air.
Block empty rack spaces with blanking panels to prevent heat recirculation.

3. Organize cables
“Tangled cables block airflow,” says Watkins. “They prevent efficient cold air distribution under raised floors and cause heat to build up inside enclosures.” In raised-floor environments, move cabling to overhead cable managers. Inside enclosures, use high-capacity cable managers to organize patch cables.

4. Replace inefficient UPS systems
“Removing unnecessary heat sources helps cool the room,” advises Watkins. Replace traditional on-line UPS systems with energy-saving SmartOnline™ models to increase efficiency and reduce heat output, especially where redundant UPS systems operate below full capacity.

5. Use close-coupled cooling
Gartner Group reports that close-coupled cooling increases efficiency compared to traditional perimeter and/or raised floor systems. “Close-coupled cooling allows you to focus cooling where it’s needed most without lowering the temperature of the entire room,” says Watkins. The modular nature of close-coupled cooling also allows data centre managers to quickly reconfigure cooling to handle new equipment or overheating racks.

Tripp Lite’s close-coupled cooling solutions are completely self-contained and can be installed by IT staff without costly contractors, plumbing, piping, special ductwork, floor drains, water tanks or extra parts. The portable SRXCOOL12K provides 12,000 BTU (3.4 kW) capacity. The row-based SRXCOOL33K has a standard 42U rack form factor, convenient L6-30P plug and provides 33,000 BTU (9.7 kW) capacity at costs up to 38% less per BTU than traditional designs. An innovative variable-speed, DC-inverter-driven compressor prevents disruptive inrush current, allows precise cooling adjustments and dynamically scales output to match the application, further reducing energy costs.

6. Isolate and remove hot air
SmartRack™ thermal duct rack enclosures route hot air through an overhead duct to the HVAC or CRAC return air stream. “They isolate hot air so it can’t recirculate in the room,” states Watkins. “Convection forces hot air up through the duct, like a chimney, and positive pressure in the room and negative pressure in the plenum increase airflow.” You can also add thermal ducts to standard SmartRack™ enclosures with the SRTHERMDUCT kit.

While effective, cooling is not the only way to reduce energy consumption in the data centre. Many people also overlook the remote management options that many PDUs Offer. For the purposes of improving energy efficiency, remote current monitoring is the most important PDU capability. Remote current monitoring reduces guesswork about how to improve energy efficiency. Not only can you see current usage in real-time, you can also review data and event logs to monitor trends and improve planning.

Some, but not all, “intelligent” PDUs not only support local and remote current monitoring per load bank or phase, but also per outlet. For example, our 3-Phase Switched PDUs have remote current monitoring per outlet, as well as our Single-Phase Switched PDUs. Because these PDUs give you more precise or granular data, you can get detailed information about how much power a specific device is drawing from a specific outlet.

Knowing how much current is being drawn by each PDU allows you to optimize efficiency more easily than if you only know what’s on your monthly bill, but it’s even more helpful to know how much current is being drawn by each outlet. Knowing the current per outlet allows you to perform device-level optimization.

Even though increasing efficiency in your data centre environment seems like a daunting task, with a few straight forward adjustments to your cooling solution and the added information that can be garnered from utilizing intelligent PDUs, it has become relatively easy to meet efficiency goals.