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Evaporative Freecool® – The Big Daddy of Data Centre Cooling?

25th, May 2015

Historically cooling is responsible for a large proportion of ‘non compute’ energy consumption within the data centre, getting the right solution to ensure ultimate efficiency is the goal of many data centre professionals.

Fortunately there are many energy efficient cooling systems on the market to satisfy most requirements many providing unique benefits, ultimately choice will be based on a range of metrics. Typically, the level of energy efficiency will be the main factor.

There are many explanations for the term ‘Efficiency’ – ‘One of the best analogies for describing efficiency in data centres has to be ‘The good use of natural energy in a way that does not waste any’ in terms of data centre cooling technology currently available on the market this terminology is probably best matched to Evaporative Cooling Systems.

Evaporative cooling is nature’s method to cool, it is the system your body uses to cool down and undoubtedly the most environmentally friendly and sustainable system by far.

So how does it work? Evaporative free air cooling technology makes use of the external air to cool the data centre environment, unlike simple air economisers which require supplemental or chilled water when external ambient temperatures exceed 210C, Evaporative Cooling Systems engage the evaporative cooling mechanism by simply passing the airflow through wet CELdek filter pads.

So what is so good about it? The primary benefit is the system significantly reduces power consumption in comparison to traditional cooling systems, indeed the well-known Freecool® Evaporative Data Centre cooling system by Workspace Technology delivers typical power consumption reduction of 90% or more compared to many traditional mechanical systems, delivering typical PUE3 of 1.15 or less, additional benefits include:-

  • Reduced CO2 emissions
  • Significantly reduced operating costs
  • Improved PUE Data Centre Efficiency Ratings
  • Improved cooling resilience with practical support by UPS systems.
  • Flexible airflow and configuration options
  • Modular, Scalable Architecture

In practical terms the benefits outlined above deliver sound financial and commercial benefits. Evaporative Cooling Systems also qualify for government grants that are available to support the installation of such systems.

Nothing is perfect so what are the drawbacks?

In the past evaporative cooling solutions have been dismissed for data centre environments due to the strict levels of air quality and humidity control that was required by legacy I.T equipment. These barriers to the use of direct free air cooling have been removed as modern computing equipment is far more robust with the ability to support wider temperature and humidity ranges.

Typical environmental operating specifications of 10ºC to 35ºC and 10% to 95% relative humidity are supported by modern computer equipment. The industry leading body ASHRAE who publishes recommended standards acknowledges the advances of modern computers and the need to balance energy efficiency against system reliability. Current ASHRAE publications outline an “Allowable” temperature range of 18ºC to 27ºC and humidity of 8% to 80% RH.

Another observation is the requirement of Evaporative Cooling Systems to use water during the cooling process.  Freecool® systems by Workspace Technology only use water when temperatures exceed the set point (typically above 21ºC), when the evaporative cooling mode is enabled the water recycled for a period of time before it is purged from the system. The use of water in Freecool® evaporative cooling systems is typically less than 25% than other adiabatic evaporative free cool plant.

It is of course true that poor air quality can cause detrimental issues where direct air is used, the designers of the Freecool® system have recognised this and have a two-fold solution. Firstly Freecool® units are fitted with “wraparound” 3G filters which in turn is combined a with secondary G4 “filter wall”. Should the air quality reduce, say for instance in the event of a localised fire the system can revert to closed loop operation if coupled with existing CRAC units or a backup system known as a Coolwall.

The “Coolwall” is designed to deliver automatic backup in the event of external air quality, internal environmental conditions, fire suppression activation or primary cooling failure conditions. The “Coolwall” chilled water coils are designed to support maximum design cooling capacity at 20ºC ambient. The “Coolwall” installation is designed to restore 100% of cooling capacity within 30 seconds of primary cooling failure.

So how about some real life examples of where this technology has been used?

Evaporative cooling technology is deployed throughout the data centre market from Telco operators, to Co-Location providers, standalone privately owned data centres to the Public Sector data centres. Two recent examples of multi-award winning data centres include Leicester City Council and the University of Aberdeen.

Both projects utilised Freecool® probably the UK’s most recognised Data Centre Evaporative cooling system by Workspace Technology. The cooling systems were a significant element of complete Design and Build solutions provided by Workspace Technology Ltd for both example projects.

University of Aberdeen

The North East Shared Services (NESS) partnership is a joint venture between the University of Aberdeen, Aberdeen College, Robert Gordon University and Banff and Buchan College. The partnership was formed to create a “Shared Services” data centre facility. The existing data centre located within the Edward Wright Building on the University of Aberdeen’s campus was selected as the preferred location. This was a legacy data supporting the University’s core ICT services. This facility had sufficient space for the estimated combined rack count but was dated and lacked the power and cooling capacity and had a very poor PUE of 2.6.

Workspace Technology’s innovative solution included Design, Civil and Construction works, Freecool®, aisle containment, Schneider Electric switchgear, backup power generation, structured cabling and Schneider / APC rack and PDUs and StruxureWare DCIM.

An annualised PUE3 of < 1.15 was achieved. The energy bill for the data centre was reduced by £94,000 per year whilst also reducing the data centre carbon foot print by 612 tonnes per year. The annual financial saving across the NESS partnership from the refurbished data centre total’s £256,000 with a combined carbon footprint reduction of 1450 tonnes.

This innovative data centre has been awarded multiple accreditations and awards including the prestigious British Computer Society – Data Centre Project of the Year, & Computer Weekly – Public Sector Data Centre of The Year 2013, and Green Gown – Effectiveness and Efficiency

Leicester City Council.

Workspace Technology delivered ‘Carbon Neutral’ Cooling, as an integral element to a complete data centre design and build project. The solution utilised Freecool® Direct Evaporative Cooling System combined with contemporary renewable Photovoltaic (PV) Technology, with back up cooling resilience supported by Workspace Technology’s Coolwall. The PV power contribution exceeds that of the Freecool® power consumption.

Freecool® installations are designed and built from scalable standardised modules that can be interconnected in a bespoke arrangement supporting ‘real world’ customer applications. The Leicester City Council project was no exception with the solution designed to support a maximum critical load of 250kW N+1 with a deployment of 9 x 30kW Freecool® units.

Workspace Technology provided a comprehensive installation including full design and installation services.

Since that data centre was commissioned in July 2015 it has won 3 awards including:-

  • Leadership in the Public Sector – DCD EMEA Awards
  • Innovation in the Public Data Centre – DCD EMEA Awards
  • Best IT/E-Commerce Project – PSS Awards),

So is Evaporative Freecool® - The Big Daddy of Data Centre Cooling?

There are of course other cooling systems that provide excellent innovations, and clearly Evaporative cooling is a cooling system that not suit all applications or preferences so is Evaporative Cooling The Big Daddy of Data Centre Cooling?- maybe not, but it certainly can be described as the “Big Green Daddy” of Cooling Systems!

For more information please contract Roy Griffiths Technical Director at or call 0121 354 4894.

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