Poor knowledge means business risk

Phil McEneaney from Stulz UK warns that a failure to understand the difference between comfort cooling and precision cooling is resulting in poorly specified equipment – leading to higher costs, IT failures and increased business risk.


oorly specified cooling technology can result in erratic climate control, increased operating expenditure, and costly disruption to IT operations. With emerging trends such as 5G, IoT, automated vehicles and digitisation in the industrial sector, there will be a dramatic increase in remote edge data centres and small, localised server rooms – reliability will be critical. But are installers of cooling solutions prepared for these developments? A lack of awareness of the differences between comfort cooling and precision cooling is impacting the reliability of IT infrastructure, resulting in serious consequences for businesses.

Around half of businesses currently install comfort cooling in small server rooms, instead of the correct precision cooling. This is a common mistake; there is a need for education on the importance of precision cooling in delivering resilient IT operations. We are frequently called in to replace inappropriate units installed in technical spaces. Comfort cooling units are designed for cooling people in offices and retail environments. This type of cooling technology is intended to operate for short periods of time and the typical life expectancy is around five years. Precision cooling is designed for use in technical environments, 24/7, with a typical life span of between 10 and 15 years.

Temperature accuracy

Stulz UK’s precision air conditioning units ensure optimum temperature accuracy with maximum tolerances of +/- 1°C and are designed to dissipate isolated thermal loads even from distant corners of the room. Comfort units can normally deviate from the set value by as much as +/- 3°C. This is significant as information and communication technology only works reliably and without faults within a relatively narrow temperature range. Other important differences also need to be understood. Comfort cooling units are designed to cater for ‘latent heat’. Environments that are populated by people (as opposed to technical equipment) produce this

32 March 2019

type of heat, which contains moisture, while technical spaces (such as server rooms) radiate pure heat – referred to in the industry as ‘sensible heat’.

A comfort cooling unit will have a typical ‘sensible heating ratio’ of between 0.5 and 0.6, while a precision unit will have a sensible heat ratio of 1.

Comfort cooling units, which are designed to remove the moisture produced in retail and office spaces, can use up to 50% of their energy for dehumidification. This is an important difference – precision air conditioning units convert more than 95% of the energy used exclusively into cooling capacity. Therefore, the technology required to achieve this pays off quickly in terms of lower operating costs.

A comfort cooling unit rated at 10kW, with a sensible heat ratio of 0.5, will only deliver 5kW of sensible cooling. A precision cooling unit with a heat ratio of 1 will deliver the full 10kW. This means you may need to specify two comfort cooling units to deliver the same capacity as one precision cooling unit.

Total cost of ownership

There are significant risks associated with inappropriate use of comfort cooling units. Unlike comfort air conditioning units, precision units feature strictly controlled and accurate dehumidification (tolerance +/- 5% relative humidity), as too much humidity can lead to condensation and corrosion, while too little can cause static charges, data loss and damage to hardware.

If you are removing moisture from the air via a comfort system, you must be aware that the air will become drier and this can lead to static build-up and failures in the technical space. We have seen instances where the client has had to purchase additional equipment to add moisture back into the room. Humidification units add an extra layer of cost to the original installation and are very expensive to run, which ultimately increases the total cost of ownership.

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