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Military precision

With energy savings of up to 80 per cent for its computer room air conditioning energy consumption, Airedale’s retrofit project for BAE Systems hit the target.

In terms of considerations when upgrading a computer room, ensuring there’s no disruptions to critical testing and production of combat and training aircraft, such as the Typhoon and Hawk Advanced Jet Trainer, has to be one of the more dramatic ones.

However, as this project was for the UK’s largest supplier to the UK Ministry of Defence (MoD), BAE Systems, it begins to have context.

The company required a cost-effective upgrade solution for its Warton site that would increase cooling performance and deliver significant energy efficiencies.

To achieve this, Airedale International’s team of engineers and controls experts worked closely with the BAE Systems sustainability team, project team and external engineering and energy advisors, Joule Consultants, to upgrade more than 70 Denco and Airedale precision air conditioning (PAC) units in more than 30 computer rooms.

To provide energy savings predictions, a trial was conducted in two separate environments to provide a business case – following additional system refinements and re-commissioning, the final savings were more than 27 per cent higher than original predictions.

The 12-month project at the high-security site involved consultancy and works across a variety of system specifications and was closely project-managed throughout.

This included replacing all necessary controllers and interface cards, re-wiring panels, installing 42 new electricity meters and replacing air filters
and water detection probes on all units.

More than 50 EC fans were also installed. EC fans are up to 70 per cent more efficient at part-load in comparison with equivalent AC fans, offering precise variable speed control matched to load and low airflow resistance, reducing fan power input, energy consumption and noise. Power usage was also reduced by retrofitting electronic expansion valves (EEVs) to 16 units.

EEVs improve EER (Energy Efficiency Ratio) by up to 30 per cent compared with standard thermostatic expansion valves and deliver very accurate refrigeration control at part-load and lower ambient conditions with a reduced condensing pressure.

To bring the units in line with current legislation, refrigerant was also reclaimed and the system pressure-tested for leaks and recharged.

In control

Airedale’s controls division also developed bespoke chilled water (CW) and mechanical direct expansion (DX) control strategies to maximise the part-load efficiencies of the Airedale chillers. CW valves maintain cooling with the fan set at 40 per cent of full capacity minimising unnecessary power consumption. As load increases, the valves open to reject heat load from the room until they reach 100 per cent, at which point the fans ramp up to precisely match capacity needs.

As the need for cooling diminishes, the fan will ramp down to 40 per cent and then, if required, the valve will start to close.

The PAC units were also networked and integrated with the existing Building Management System (BMS), providing remote temperature and humidity management.

To minimise power consumption and provide redundancy, the PAC units are programmed to operate in run/standby mode, alternating after a set number of hours – this ensures even wear of components and provides back-up in the case of maintenance downtime.

Joule Consultants could also tailor controls strategy and air balance to individual room conditions, minimising energy consumption while maintaining close temperature and humidity control.

BAE Systems has achieved annual savings of 70-80 per cent on its computer room air conditioning energy consumption, equivalent to £350,000 at a major Military Air & Information sites in north-west England.

The business expects to recoup the costs of the project within just 15 months.

Adrian Trevelyan is aftersales manager at Airdale International

Data centre retrofit market

The opportunity for retrofit is significant when you consider how many legacy data centres there are as a proportion of new-builds. It’s an area where Airedale has been active since 2005 and has built considerable expertise working with clients such as Epson, the National Gallery and Reuters.

As the BAE Systems project shows, legacy environments can benefit hugely from the latest technologies and there is a great deal of flexibility in how they might upgrade. This could range from replacing a complete unit to upgrading components to the latest energy-efficient alternatives such as EC fans, Electronic Expansion Valves (EEVs) and implementing bespoke controls strategies. The efficiency savings, which can be substantial, can be used to fund the client’s next project.

Typically, Airedale would conduct a free energy survey following, in which it would monitor and measure energy consumption over a period of time, usually one day or one week, depending on the client’s requirements.

Then Airedale would continue to monitor and measure performance over the same period of time to ensure like-for-like comparisons.  In conjunction with the client, Airedale would assess the results and help build a business case as a basis for rolling out an upgrade programme within the facility.

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