DCN August 2017 - Page 19

Cooling ‘Statistics show that cooling in the data centre space accounts for 40 per cent of the power used in the entire facility.’ Rack airflow management using chimneys Similar to my experience with running, I’ve found that operating an efficient data centre also takes constant evaluation and adjustment. I recently read an article which stated that cooling the data centre accounts for 40 per cent of the power used throughout an entire facility. My experience has taught me that an area ripe for fine-tuning in data centres is airflow management at the cabinet level, particularly by using chimney systems. For data centre managers to optimise their cooling efforts through implementing chimney systems, it is important to first recognise the similarities and then note the differences between active and passive chimney systems. Both active and passive chimney systems will use a well-sealed cabinet, designed to minimise the amount of hot air that can escape back into the cold aisles. In both configurations, the goal is the same: To get cool air to pass through critical rack equipment and move hot air into a return plenum using air containment. With active cooling, cabinets rely on energy efficient exhaust fans positioned at the top of racks to assist with pushing air into the return plenum. As a result, airflow becomes less reliant on server fans. An active system is more responsive than a passive system. This is because the speed of the fans being used to direct hot air into the return plenum can adjust to make up for back pressures in return plenum or for varying airflow of the equipment in the rack. A passive system relies entirely on the server fans to drive the flow of cold air through the equipment and to subsequently channel the exhaust through a duct, back to the return plenum. In turn, passive cooling could expend less energy than active cooling if a negative return plenum pressure is maintained. August 2017 | 19