Technical guidance: HVAC and chiller systems
compromise human life in a hospital, and our aim is to ensure that this doesn’t happen.
Mirroring data centre practice? “We find that data centres employ an N+1 approach with their HVAC maintenance because of the imperative to keep valuable data safe and available. Healthcare facilities could benefit from adopting similar practices to those of data centres, although budgets might preclude this. Many data centres employ an N+1 approach (nominal plus one), which is a solution for companies looking to reduce downtime and minimise costs by providing back-up equipment to work alongside the chillers, serving critical components and site activities. An N+1 approach is becoming more and more popular, since, ultimately, a secondary (back-up) system may not be used for many years, and may not operate at its best after lying dormant for long periods.
A rental configuration for a hospital.
Our multi-scroll chiller ranges feature multi-circuits which also cater for a range of industrial processes and HVAC applications, and work with the ‘ozone- friendly’ R410A refrigerant to ensure energy efficiency and reduced carbon footprint.”
Benefits of an N+1 approach “There is more chance of failure without an N+1 arrangement, as the standby unit can fail where only one mechanical item is being used at a time, and, if one part does fail, then the whole system is jeopardised. Rental contingency packages not only guarantee a back-up cooling package on site which companies such as ours can install within 24 hours, but also meet standard industry requirements to ensure a smooth transition of equipment.”
Can you give some general guidance on the type of HVAC equipment that you recommend? AdamSpolnik: “Although deciding which equipment to use is largely dictated by the application that it is supporting, we are mindful of the need to provide the most energy-efficient solution to reduce maintenance and refrigeration costs, and in few places is this as important as in publicly-funded healthcare. There is a large range of equipment available for hospitals and other healthcare facilities, such as HVAC chillers for comfort cooling applications, as well as process-biased smaller chillers which can be used for MRI and CT scanner applications. “Large HVAC units have much more
efficiency gains with varying loads, and ambient temperatures mean that there is more drive with a Turbocor range, or multi-scroll chillers. Some ranges feature Turbocor compressor technology, which provides high partial load efficiency levels, and can adapt to various thermal load conditions, offering minimum running costs to the unit in real working conditions, with low sound levels.
22 Health Estate Journal September 2013
Can you talk a little about some of the key cooling technologies? RichardMetcalfe: “We have recently worked with a leading healthcare provider, recognised for its clinical excellence, to provide a total temperature solution with a number of our APTUS multi-scroll chillers, for a complex project involving the replacement of cooling systems for the organisation’s estate of over 60 hospitals throughout the UK. “Essentially, there are three ways in
which to provide cooling; ambient air/dry air cooling, cooling towers (or adiabatics), and mechanical refrigeration-based cooling. The particular temperatures required dictate which system you need to use, and each technology has a unique way of handling the temperature requirements. “Dry air coolers produce temperatures
three to five degrees higher than the ambient temperature, while evaporative systems such as cooling towers or adiabatic units produce temperatures three to five degrees lower than the dry bulb ambient temperature – by adding moisture to the air to create a cooling effect. Mechanical refrigeration-based chillers will work to whatever condition they are set at, ‘24/7’, provided that the unit itself is designed to work in the right conditions, although these chillers are not always the most cost-effective.
Evaporative systems “If consideration is given to an evaporative system, we recommend that healthcare organisations consider an adiabatic solution, as the units present a much lower potential risk than cooling towers, which have been found, in the past, to contain traces of Legionella. Adiabatic coolers consume a quarter of the water of cooling towers, and should operate at a third of the running costs.We find that it is better to support water-cooled chillers this way.”
What about any particular cooling/chilling requirements for diagnostic imaging units? AdamSpolnik: “We recommend that healthcare facilities use smaller chillers to support small units such as MRI or CT scanners. Our equipment range features units that work independently with each scanner that will not source their power from the central system; they are dedicated to the one machine they are connected to. These
units are robust and industrial, and their predecessors are synonymous with the healthcare marketplace. “We recently supported a medical
research facility by providing an 88 kW TAEevo 301 chiller to deliver chilled water to the head of a scanner. The entire solution encompassed a preventative maintenance contract and remote monitoring of the scanner’s chiller, with access to operating data for the chiller available both on and off site, to ensure that the equipment is functioning as normal at any given time.
What about the carbon reduction and other ‘environmental’ considerations when selecting HVAC equipment and chillers? RichardMetcalfe: “Overall, the Government is committed to reducing the UK’s greenhouse gas emissions by 80% by 2050, compared with the 1990 levels. There has been progress, with, for instance, bodies such as the NHS Sustainable Development Unit (SDU) providing valuable support to healthcare organisations in their own carbon reduction campaigns and initiatives, while developing new plans of action and carbon-reducing strategies for the healthcare sector. The latest NHS Carbon Footprint data
(2012) shows that carbon emissions for NHS England have stopped rising, and are, in fact, now levelling off. (The latest NHS Carbon Footprint was calculated as part of the NHS SDU’s Sustainability in the NHS: Health Check 2012 publication,1
and has
been used in the Carbon Reduction Strategy. The NHS carbon footprint now stands at 20million tonnes of carbon dioxide equivalents (MtCO2
e) – using 2010
data – ‘a drop of onemillion tonnes compared with the last time the footprint was calculated, in 2007’. The footprint (in a basic form) is composed of building energy (24%), travel (17%) and procurement (59%).
AdamSpolnik: “The benefits of less carbon-intensive and more energy-efficient HVAC equipment to the healthcare sector are huge.We have criteria to meet EU directives and reduce carbon emissions, and can potentially help the sector to secure energy savings and carbon
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