IT COOLING
Poor cooling knowledge can lead to ‘costly mistakes’
With patient safety a priority, NHS staff need uninterrupted access to clinical data 24 hours per day, 365 days a year. 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 risk’.
Hospitals need to ensure constant uptime of their IT infrastructure. Investment in reliable cooling is a fundamental aspect of this requirement – server rooms that are subjected to high thermal loads need constant climatic conditions in order to work reliably.
Poorly specified cooling technology can result in erratic climate control, increased operating expenditure, and costly disruption to IT operations. In recent years, the government and national NHS leaders have set out a high-level vision and goals for digitising the NHS. From life- saving decision-making tools and patient monitoring technologies, to electronic patient records and tracking of medical devices, reliable IT has become the backbone of the NHS, and is critical to the delivery of safe, efficient care. However, 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 hospitals and the NHS. Far too many hospitals and medical centres 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.
Limited operating duration 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 (of around five hours per day, five days per week), and the typical life expectancy for a unit is around five years. Precision cooling, on the other hand, is designed for use in technical environments, 24 hours per day, seven days per week, and the typical lifespan is much longer – usually between 10 and 15 years.
110 Health Estate Journal October 2019 An important difference
Stulz Air distribution with speed- controlled EC fan technology.
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, on the other hand, 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. There are other important differences that also need to be understood, however.
Comfort cooling units, as part of their design, are designed to cater for ‘latent heat’. Environments that are populated by people (as opposed to technical equipment) produce this 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 hospital wards, offices and non-technical areas 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, producing energy efficiency and power saving opportunities. In fact, a precision cooling unit will use up to 50% less energy to run than a comfort unit of same capacity. Therefore, the technology required to achieve this pays off quickly in terms of lower operating costs. A comfort cooling unit rated at 10 kW, with a sensible heat ratio of 0.5, will only deliver 5 kW of sensible cooling. A precision cooling unit, with a heat ratio of 1, on the other hand, will deliver the full 10 kW. 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, which installers need to be aware of. Unlike comfort air-conditioning units, precision units feature strictly controlled and accurate dehumidification (with a tolerance of +/–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 that this can lead to static build-up in the technical space. These static shocks can be quite powerful, and lead to failures of sensitive electronic equipment. We have seen instances where comfort cooling units have been specified, and the client has had to purchase additional equipment to add moisture to 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 of comfort cooling solutions.
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