HEALTHCARE VENTILATION
Managing critical systems is often a challenging task
Simon Everett, a Senior lecturer in the Built Environment at Wrexham University, discusses some of the challenges of managing ‘legacy’ AHU systems across the healthcare estate, and some of the key steps for healthcare engineers to consider to minimise the risks of such equipment failing.
Critical ventilation systems, i.e. those serving areas that cannot function safely without such systems (for a full list see HTM 03-01 a, paragraph 4.311
) in healthcare
premises, when designed, installed, and maintained correctly, help control the spread of airborne pathogens through the dilution and removal of contaminated air. Not all systems comply with current standards, and even some of those may not meet their design specifications – which may go unnoticed until their annual verification. For Estates teams, managing risks associated with legacy equipment is a significant and complex challenge. Assessing the condition of air-handling units (AHUs) regularly is important from a maintenance perspective, but is also crucial for effective lifecycle management, because early warnings can help avoid costly and sometimes catastrophic failure of the equipment, which in turn poses the risk of service interruption, infection control issues, and other safety considerations.
Competing with other capital funding requests NHS Estates teams are often competing with other capital requests, and often clinical needs trump infrastructure, but is this because of a lack of understanding at a strategic level, and what happens when infection rates in operating theatres soar, and Infection Prevention and Control (IPC) teams investigate the root cause? From an Estates perspective, ensuring that AHUs have been maintained to the correct standard is vital, then. The plant should be performing to criteria laid out in HTM 03-01, but this might not always be the case – particularly with respect to plant installed prior to the most recent guidance. There should be annual verification and performance testing conducted, with performance compared with the
A modern UCV theatre air-handling unit.
validation figures obtained at the time of installation and commissioning. The values measured must achieve a minimum of 80% of the original air-change rate (HTM 03-01b, paragraph 4.16). The HTM makes the point that systems nearing their end of life may reduce in performance: “it is to be expected that over the lifetime (typically 20 years) of a ventilation system its performance will gradually reduce...” (paragraph 24, part B). However, the HTM is clear that equipment that is not performing to the required criteria should not be used. In this instance, what options should Estates teams consider? In this article, we will discuss the pitfalls
facing Estates teams, focusing on critical ventilation air plant, and suggest strategies for managing capital budget expectations, IPC risks, and operational and compliance considerations.
Pragmatism or idealism? With no data specifying the number of AHU systems in hospitals at the end of (or nearing) their useful life currently publicly available, it’s difficult to arrive at an accurate cost of replacing or upgrading to condition B all units across the country. However, for Trusts that operate and maintain legacy AHU systems, it is likely there will be other backlog issues
for its buildings such as heating or fire compartmentation. Where there are life- critical safety implications (for example, fire protection), these will often trump less ‘visible’ – but potentially as critical – legacy plant such as AHUs because of perceived risk.
Understanding the backlog profile of
the estate should be a priority for Estates management teams, but often the correct methods are not employed. For Trusts in England, responses from the latest Estates Return Information Collection (ERIC) data2
indicate that approximately
41% of sites had been surveyed formally, and just over 20%, since 2018. The latter figure is significant, as this might indicate an established rolling programme. Those sites with up-to-date backlog data are likely to be much better informed on their position, and have a better understanding of where their assets are in their lifecycle. This doesn’t necessarily mean that there is detailed information for any AHUs on the site. For critical ventilation plant (as defined in paragraph 4.7 of HTM 03-01b), a key document in understanding current performance capability would be the annual verification report. This document will identify whether the equipment meets the requirements set out in HTM 03-01, and – crucially – where, and why.
September 2024 Health Estate Journal 67
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