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CASE STUDY
amount of time free cooling could be utilised .
The second option was the EcoCooling CREC ( Computer Room Evaporative Cooling ) solution , which incorporates evaporative cooling into a ventilation system . Evaporative cooling is a very simple method of cooling air without using refrigerants . A direct evaporative cooler , using wetted filter pads , cools outside air by bringing it into contact with water . Water evaporates into the air stream and cools it . The amount of cooling is dependent upon the temperature and relative humidity of the air . In the UK , the maximum theoretical airoff temperature is 22 ° C . In practice , the actual temperatures achieved using evaporative coolers in UK data centres can approach 24 ° C on the very warmest days . This allows full compliance with ASHRAE temperature standards .
All about the ambient For most of the time , UK ambient air temperature is colder than that required in the data centre – so a simple ventilation system can maintain compliant conditions . This can remove the need for cooling for up to 95 % of the time in the UK and similar climates . The EcoCooling CREC system uses Electrically Commutated ( EC ) axial fans , which offer the lowest energy ventilation systems on the market . A 100kW data centre like the TalkTalk ’ s in Ireland could be ventilated using EC fans consuming less than 5kW . This means the ventilation system would only add a maximum of 0.05 to the PUE of the data centre . In addition to this , TalkTalk also looked at minimising the fan speeds to greatly reduces energy use . As a rule of thumb , a fan running at half speed uses 12.5 % of the full speed power . When data centres are partly populated then variable speed EC fans exploit this principal .
The combination of a ventilation system using EC fans and evaporative cooling would provide TalkTalk with a cooling solution with a CoP of over 20 and conditions that would enable them to keep the data centre within acceptable ASHRAE conditions for 98 % of the time , at a fraction of the energy cost . It also provided them with an energy efficient solution to run a partially populated data centre without the drawbacks of high initial PUE ’ s .
Their test laboratory data centre facility at Irlam near Manchester was chosen for the first project as the existing cooling system was both under performing and consuming a lot of energy . Two EcoCooling CRECs were installed on the roof of the building as part of a fresh air ventilation system to provide 100kW of cooling to the main server room . Each system has two coolers bringing air into the building and distribute it through vents directly into the centre of the server room ( which has no containment ). Highly efficient EC fans are used for the supply and extract air from the building .
The existing DX system has been retained to provide backup in the unlikely event it should be required . The new system has increased the cooling capacity and reduced the energy consumption from ~ 16kVA to ~ 2kVA (~ 87 % power reduction ).
Two of the three planned sites are now completed and TalkTalk are in the process of finishing off the installation on their third site . Mark Jacobs , Energy & Facilities Manager said : “ We are extremely happy with the performance of our EcoCoolers , the system consumes 87 % less power than the previous DX system did and our data hall is now cooler than it ever was before . We were expecting to have to utilise the secondary system ( DX ) occasionally , but the EcoCooling system has performed very well and the secondary system has remained off . We are now installing EcoCooling CRECs in 2 further data centres .” n
The graph above shows the instantaneous use of electricity for the cooling system at Irlam , and clearly displays the reduction achieved when the CREC system was introduced at the data centres .
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