Legacy Data Center Energy Efficiency Upgrade

Location: London, UK

Comprehensive Cooling Optimisation and Energy-Efficiency Enhancement in a Legacy Data Center

The client was a global financial services enterprise operating a network of high‑availability data centers. This project focused on one of its major facilities located in the greater London area.

The client required a significant reduction in energy consumption and operational cost within their 2007-built legacy data center, without compromising its high availability or reliability. The facility exhibited a high Power Usage Effectiveness (PUE) of 2.3, driven largely by inefficient chilled‑water cooling and air management practices. The organisation needed a solution that could be implemented in a live operational environment, managed carefully to avoid service disruptions, and aligned with best practice guidelines for modernised data center cooling performance.

Our approach

The project was delivered through a phased engineering program beginning with a detailed energy assessment and data hall air temperature survey. These diagnostic steps revealed substantial bypass airflow, warm air recirculation, and excessive fan energy consumption.

Based on these findings, the team implemented a suite of air management improvements, including installing blanking panels, sealing raised-floor gaps, repositioning floor grilles, and deploying temporary then permanent cold‑aisle containment. These measures enabled a shift to lower CRAH fan speeds and a reconfiguration from return‑air to supply‑air control.

As conditions stabilised, air and chilled‑water temperature setpoints were gradually increased, boosting chiller efficiency while maintaining safe server inlet temperatures. A subsequent free‑cooling feasibility study identified that installing four high‑capacity dry coolers would provide substantial additional savings. The dry coolers were integrated into the return side of the chilled‑water system, allowing extended periods of full and partial free cooling.

Key facts

Initial PUE: 2.3
Resulting PUE: 1.49 (34–35% reduction)
Annual Energy Savings: $1.7 million
IT Load: 1800 kW
Cooling Infrastructure: 56 CRAH units; redundant 2N/Tier 3–4 topology
Data Hall Size: 3500 m² (38,000 ft²)

Services

The project consisted of the following service areas:

Environmental & Sustainability

End result

The project delivered a transformative improvement in energy performance. The data center achieved an estimated annual PUE of 1.49, reducing electricity expenditure from $4.7 million to $3.0 million per year. Beyond the financial and environmental benefits, the initiative strengthened operational expertise, increased staff engagement, and created a repeatable model for similar upgrades across the client’s global portfolio.