With state-of-the-art MEP infrastructure and networking equipment, NTT Communications Hong Kong Financial Data Centre Tower 2 (FDC2) is designed to be compliant to Tier IV of the Uptime Institute’s multi-tier requirements, the highest rating measuring the quality and reliability designed into a data centre.

As the mechanical, electrical, public health, IT and security engineering consultant, Arup worked with the client to devise a number of innovative solutions to help the premium mission critical facility meet the challenge of reliability and achieving both energy efficiency and design flexibility.

Unique emergency cooling strategy

A continuous cooling system is vital to achieve non-stop operation of the data centre. To deliver on FDC2’s promise of 100% uptime, we helped our client to realise a cutting-edge cooling strategy using two thermal energy storage (TES) tanks employing the water stratification principle, the first of its kind in Hong Kong.

The water stratification principle relies on a fundamental property of water. Since water density is inversely proportional to temperature, hot and cold water can be naturally kept apart with the hotter, lighter water above a thermocline separation. The designed cold-water temperature and volume can then be secured during the operation at all times and scenarios to feed the data centre cooling system with the return hot water trapped in the upper layer.

In this project, two TES tanks were designed to ensure hot-cold water separation. Using a computational fluid dynamics simulation for verification, we designed the water inlet and outlet diffuser to ensure a steady water flow for the formation of the thermocline layer and the natural water temperature stratification.

Energy efficiency

Given the high power demand of the data centre, various cooling approaches were employed to improve energy efficiency and save costs for the client. These include front-flow air handling units, indirect free cooling from the cooling towers in winter, and efficient plant design.

As a result, the annualized power usage effectiveness (PUE) value can achieve below 1.5 at full load condition, compared with the local average of 2.3.

Design flexibility

Designed to be a future-proof facility, FDC2 adopts a modular design to allow for phased capital investment (to reach the ultimate capacity of 4,200 racks) as well as flexibility for end-users to tailor their solutions in the future with a wide power density ranging from 4kW to 24kW per rack.

This also allows the building to react to changing business requirements and technological advancement in the future with minimum impact on the operation, facilitating deployment, saving costs and reducing risks to other operating areas.

BIM as a process

We formulated a fully built BIM model throughout the design life cycle, the first time for the local data centre market. Through this project, BIM has advanced from being a tool to a truly collaborative process, enabling coordinated working, clash reduction, design optimisation and improved efficiency.