Tokyo, Japan, 24 May 2018: AT Tokyo, a data centre solutions provider based in Japan, believes that optimum performance of cooling within computer rooms can be achieved in an energy-efficient manner, while ensuring high reliability in operations, said Hisashi Ito, Associate Director.

Ito highlighted three of the operational measures being implemented in the company’s newest data centres. The first, he said, is rack temperature management based on intake of temperature at the top of each rack. As an example, Ito points to fan-speed feedback based on IT rack-top temperature and temperature management at the top, middle and bottom of each IT rack, using Data Centre Infrastructure Management (DCIM). Second, Ito said, is the prevention of short-circuit airflow from hot aisles to cold aisles. Third, Ito said, is levelling of power consumption. “Load levelling of utility power usage using large-scale thermal storage is required,” he said. “Chiller efficiency is improved by utilising wet bulb temperature-based control of cooling towers. Due to the relative abundance of water over electricity in Tokyo area, the control algorithm optimises power usage over water usage.”

Touching on challenges surrounding data centres in general, Ito discussed two main issues:  dealing with increasing thermal density of IT equipment mounted in racks and degradation of cooling performance and efficiency due to blockage caused by increasing cable volume under the raised floor in older data centres. In the first, he said, measures such as the use of Vertically Stacked Cooling Architecture, where computer room air handler (CRAH) units are mounted directly below IT racks in a separate mechanical floor, aisle containment and use of high efficiency/output CRAH units, are adopted. For the second issue, Ito said, AT Tokyo’s in-house mechanical engineers perform computational fluid dynamics analysis to optimise equipment positioning and under-floor cabling, and offer consulting services to customers to improve cooling performance.

In Tokyo, Ito said, data centres are faced with high temperature and humidity in summer, low temperature and humidity in winter, and medium temperature and humidity in spring and autumn. As such, Ito said, while outside air cooling is efficient in terms of apparent heat, much energy is wasted in dealing with dehumidification and reheating during summer. Also, he says, where the salt content in the atmosphere is high, desalination of outside air is also necessary. As such, the company has decided to minimise the volume of outside air brought inside. “Our computer rooms have minimal ventilation for the aforementioned reasons,” he said, “Instead, we have maximised the window of water-side free cooling by raising the chilled water temperature and expanding the free cooling window outside winter.” AT Tokyo, Ito said, uses a rotary desiccant type AHU to regulate and control the humidity of outside air brought into the data centre. Ito stressed that while he spoke on behalf of AT Tokyo Corporation, the whole operations are carried out by a team.

Hannah Jo Uy is Features Writer at Climate Control Middle East magazine. She may be contacted at hannah@cpi-industry.com