Diamond Light Source

Diamond Light Source fan upgrade

A project in collaboration with ebm-papst, STULZ Ltd and Cinque Energy Solutions Ltd

This case study outlines how ebm-papst, Cinque Energy Solutions and STULZ are working together to provide energy saving solutions to their customers. In this example one of the UK's leading scientific organisations dramatically reduced their cooling energy consumption, by simply upgrading their existing air-conditioning equipment to use ebm-papst EC fans.

The customer commented:

"As a Scientific organisation, the project appealed to us on several levels. Obviously the financial savings from reduced energy consumption and increased reliability were of great importance. Other key benefits from the modifications ebm-papst offered, were the reduction in both noise and vibration. These can affect our operations significantly. Following the change of fans, one of operators stated he now had to give a unit the 'cuddle test' to confirm the unit was running following the significant reduction in noise and vibration!"

Project Background

The inception of the project was mid 2012 when STULZ requested us to carry out a site survey for upgrading some of their computer room air conditioners. Normally this type of unit is used for datacentre cooling but in this case the equipment was being used to cool electronic equipment rooms around the perimeter of the Diamond Light Source synchrotron in Didcot.

Phase 1 of the project was to upgrade 29 x CCD900CW STULZ downflow CRAC units from their traditional AC forward curved centrifugal blowers to EC backward curved impellers.

The initial site survey was carried out to ascertain what the current solution delivered in terms of power draw and performance. Suitability for upgrade also had to be considered. The blowers would be replaced by EC backward curved impellers but due to the limitiation of the scoop which feeds the air into the room, the EC solution had to be mounted within the CRAC unit enclosure rather than below. The proposed solution was to use the latest RadiCal 560 mm impeller from ebm-papst which offers excellent energy efficiency.

The fans would be mounted into bespoke metalwork frames to angle the airflow to assist with the air delivery into the room. The metalwork and assembly are all carried out at ebm-papst UK Ltd where we have a dedicated production area capable of offering custom solutions. An initial survey was carried out and the results presented to STULZ and the end client, with a view to carry out a single unit trial to prove the concept.

Image of impeller "RadiCal 560 mm"
Unit typeSTULZ CCD900CW chilled water CRAC
Number of units29
% energy saving~ 39 %

Trial & Energy Analysis

In January 2013, the trial installation of one unit was carried out by Cinque Energy Solutions. The aim of the trial was to confirm the bespoke design and prove the potential energy saving and benefits to the customer. Initial results showed a 43% improvement in kVA compared with the original AC fans. For the trial the unit was not physically modified, which allowed the potential to revert back to the original set up if desired. It was agreed that for the complete upgrade that the floor of the CRAC unit would be opened up further to allow the new fans a less restrictive system resistance to increase efficiency further.

The trial unit was set up to match the previous airflow but due to the simplicity of the control of EC fans, a simple manual 0-10v controller was fitted to the CRAC unit to allow each unit to be tuned to the room requirements. Over the course of a few months the maintenance team was able to adjust the fan speed to optimise the solution even further.

Chart showing kVA improvement
Number of units29
% energy saving~ 55 %
Carbon reduction/annum~ 50 tonnes
Annual energy saving~ £ 36k

Project Implementation

The upgrade of the 29 units was scheduled to be completed during a 'shutdown period' in August 2013. The complete upgrade had to be finished within a 2 week window so 2 teams from Cinque Energy Solutions were deployed to work on units simultaneously. All 54 fans were delivered to site and positioned near the units to cut down on delays during the conversion.

Step 1: Remove the original AC fans and motor system

Step 2: Enlarge the outlet holes in the floor void to maximise airflow with the EC fan solution

Step 3: Fit new EC fans and frames

Step 4: Reconnect supply to fans and fit manual speed controller

Diamond Light Source air conditioning unit with upgraded fans

After the complete installation, the original unit which had previously been measured for the trial, was remeasured following the floor pan being opened up to the designed requirements. This in addition to the fine tuning of the fan performance gave the following improved results.

Chart showing kVA improvement

The improvement in kW's even with the skew of improvement in power factor (0.6 to 0.9) also gave an improved result compared to initial estimations.

Chart showing kW improvement

Additional Benefits

As well as the significant energy saving achieved by converting to EC fans, other benefits also came out of the conversion which proved to be as important for the customer. Due to the sensitivity of the equipment being used in the Synchrotron, improvements in noise and vibration from using EC fans was also an advantage. The other benefits from the upgrade include:

  • Extended fan life
  • Extended unit life
  • Reduced maintenance – no belts
  • No belt dust being blown into the equipment rooms
  • Controllability of cooling capacity
  • Greater flexibility for capacity management


The successful completion of phase 1 of the EC upgrade has led to a 55 % energy saving from the original AC fans, bringing a £ 36k energy saving per annum as well as significantly reducing noise and vibration from the units being transmitted into other parts of the building. Phase 2 of the project, to convert the remaining STULZ cooling units is scheduled for upgrade at the next shutdown period.

  • STULZ Project Diamond Light

    Diamond Light Source fan upgrade project in collaboration with Stulz Ltd and Cinque Energy Solutions Ltd

    • File: STULZ_Project_DiamondLight_0216_en.pdf

    • Type: Adobe PDF

    • Size: 3,13 MB

    • Language: English

    • Date: 2016-02-01

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