Holborn goes against the flow for data centre upgrade

Headquartered in the UK, this recently acquired client designs, builds and operates large parts of the UK payments infrastructure. This infrastructure underpins the provision of the systems and relies on its own data centres across the country to handle tens of billions of transactions every year.

Project to raise a tier

The objective of this 13-month project was to upgrade the air conditioning to two data centres as part of a wider project to help them achieve Tier 3 classification, which requires an 99.98% availability.

Working closely with client’s mechanical engineering consultants, the decision was made to switch the airflow round in the data centre to adopt the now accepted best practice of blowing cool air through floor grilles.

This required work to be undertaken in stages with the CRAC units brought online first in the new configuration, before the air handling units (AHU) were re-configured. This would allow the data centre to keep working throughout the duration of the project.

As the main contractor, Holborn was responsible for overseeing work by all the sub-contractors, including the AHU re-configuration by Metair and the upgrading of the control systems, by Johnson Controls.

Small space, large works, big impact

Given the original air flow was in the opposite direction, the first task of the project was a professional deep clean of the ceiling and floor voids in both data centres, carried out by specialist contractors.

Once the risk of airborne debris was minimised, the next phase of the project was the supply and installation of 7 ‘DX’ cooling system units, incorporating Uniflair indoor down-flow, cooling only units, along with 14 air cooled condensers and associated pipework, condensate pipework, associated electrical services, automatic controls and BMS.

The second, slightly smaller data centre only required the supply and installation of 3 ‘DX’ cooling system units, with 3 indoor down-flow, cooling only units and 6 air-cooled condensers and associated pipework.

Holborn also replaced all the existing floor grilles to meet the requirements of the new air handling units, with new ceiling grilles and tiles also required, to allow installation of the ‘DX’ units pipework and associated cable trays.

Once the new ‘DX’ cooling systems were installed, tested and commissioned in accordance with the current CIBSE requirements, they were run for one week to demonstrate their capabilities.

With responsibility for cooling switched to the CRAC units, the next phase of the project, the complicated re-configuration of the existing air handling systems could begin.

The AHU’s were to be switched around to reverse the air flow in the data centres and first had their power supplies and automatic controls disconnected.

The supply and extract air systems from the AHU were then isolated, utilising the motorised fire dampers installed in the ductwork. Next the chilled water system was isolated utilising the existing isolating valves on the flow and return pipework.

Given the size and position of the ductwork in the plantroom, the AHU had to removed, turned around and then re-fitted, with all the necessary changes to the electrical and water systems completed.

To help improve energy efficiency, the modified chilled water pipework was thermally insulated, vapour sealed and protected using aluminium hammer cladding, in accordance with the standard mechanical services specification.

Once the AHU re-configuration was complete, the system was tested and commissioned to ensure everything was running optimally. Following a successful test, cooling responsibility was switched back to the AHU, with the CRAC’s taking back their back-up role.

Outcome achieved – cool

The ultimate aim of the overall project was for the data centres to achieve Tier 3 classification, but Holborn’s role was to improve the resilience of the cooling systems, which play an obvious role in the operation of any data centre.

The desired outcome was achieved and thanks to new Uniflair direct expansion units, the client is assured of owning data centres with air cooling at the leading edge of performance and efficiency.

Our ability to cope with every aspect of projects of this magnitude, whilst working safely and efficiently on site, instils our clients with confidence that whatever challenge arises, we will deliver a pragmatic solution to keep work on track.