Our client, a major UK based telecommunications company, was faced with an IT equipment technology change across four ageing sites. The four legacy data centres, built in the early 1980’s, had already undergone several upgrades in line with IT platform service expansions and technology refresh requirements.

The clients brief was to conduct a complete review of the existing cooling infrastructure. This was to enable a pending IT technology change which would deploy multiple 60kW IT pods with enclosed cold aisles. This upgrade would replace the common uniform forward facing or rack suite lines in one direction.

The key performance driver was to provide an efficient cooling design with a PUE of 1.3 and deliver cooling redundancy per data hall to N+2 in cooling modules.


The Qe design team carried out detailed site surveys to establish the most energy efficient solutions using our range of Qe free cooling capability products. It was noted at survey that the existing cooling plant across all four sites were operating at a low efficiency due to being several years beyond their nominal service life.

The client acknowledged that in order to maximise air volume delivery efficiency throughout the underfloor plenum, extensive work was needed to recover cables in the raised floor air plenum and to install the new efficient airflow vented floor tiles.

Our technical solution was to depart from deploying a replacement like for like chilled water systems with central chiller plant and pump modules and multiple data hall CRAHs. That was the main cooling topology strategy installed in three out of the four sites, with the fourth site having a high percentage of DX CRAC’s and a small amount of Glycol Dry Cooler CRAC’s.

Our team utilised Qe’s extensive modular CRAC units, with free cooling capability, to reduce the energy profile as low as practically possible across all four sites. The design team ascertained that the existing CRAH positions would allow for the Qe fresh air free cooling CRAC units to be deployed. Where external walls or space to deploy fresh air ducting to the New Qe CRAC-FA units was not possible, Qe CRAC Glycol Units with free cooling coils were deployed. Some DX only CRACs had to be deployed where under floor conditions prevented deployment of CRAC-FA and CRAC Glycol units but these were kept to a minimum, and no more than two per data hall were deployed to keep within the N+2 redundancy criteria, so that N cooling capacity would be biased to the Qe free cooling units.

All the Qe CRAC cooling products feature energy saving EC fan technology that modulates the fan speed / air volume to give close temperature control. The benefit of using fresh air free cooling in the UK allows for free cooling to satisfy IT load cooling requirements for 73% (6,394 hours) of the year. The remaining 27% (2,366 hours) the unit will be using refrigerant Dx cooling to satisfy the IT cooling load. Dx cooling mode affords electronic expansion valves to provide precise refrigerant volume flow to closely match the load requirement presented to the evaporator coil.


This has been a highly successful project for the client delivered over a twelve-month period that has delivered significant energy savings to their operational P&L bottom line. Also underpinning their capability in delivering high resiliency and reliability levels to the services they provide to their customers.

The impact on the environment, carbon footprint and global warming have all been significantly reduced by the annual equivalent of 6,623 metric tonnes of CO2.