HEALTHCARE VENTILATION
COVID-19 puts efficient and reliable running into focus
With input from her colleague and MD, Authorising Engineer (Ventilation), David Livingstone, Dr Louise Webb, Project director at DRLC – a provider of authorising and regulatory compliance consultancy services for the healthcare estates and healthcare engineering sector, considers the key steps for keeping air- handling and other vital ventilation plant in healthcare facilities running both reliably, and – with the drive towards Net Zero – as efficiently and sustainably as possible.
The COVID-19 pandemic has focussed attention on how buildings, and particularly those within the healthcare estate, are ventilated. Ventilation, both natural and mechanical, uses energy, especially in UK winter months, and of course NHS Trusts are simultaneously under increasing pressure to reduce their energy consumption and carton emissions in the drive towards Net Zero Carbon. Nick Evans, Energy Environment Sustainability manager for Lincolnshire Partnership NHS Foundation Trust (LPFT) and Lincolnshire Community Health Service NHS Trust (LCHS), says of the issues he faces in moving a mental healthcare Trust and supporting a community healthcare Trust in Lincolnshire towards Net Zero Carbon: “Our building stock at LPFT and LCHS ranges from Victorian buildings to premises currently under construction, with the majority of the buildings constructed from the mid-1970s to the early 1990s. With the ever-increasing need to move away from fossil fuel heating systems, and to utilise renewable, more sustainable technology, there will be an increased demand on the amount of electricity consumed. We therefore need to explore every opportunity to increase the energy efficiency of our buildings, and reduce our energy consumption.
AHUs’ greater energy efficiency “One area we are currently looking into,” Nick Evans explains, “is replacing existing old belt-driven ventilation plant with more energy-efficient air-handling units (AHUs) through the use of direct drive fan technology. With such units offering potential energy efficiency of up to 98%, compared with efficiency as low as 50% from belt-driven electric motors, there are significant energy savings to be made. To enable us to move away from our reliance on fossil fuel heating systems, I have been researching and investigating how we can use air and ground source heat pumps for our standalone mental health units and health clinics. Lincolnshire has a lot
54 Health Estate Journal February 2022
Treatment rooms are recommended to have 10 air changes / hour, and where there is no mechanical ventilation, this is being achieved by opening windows, which in winter adds to the heating bills. Authorising Engineer, David Livingstone,
Figure 1: An Air Sentry air purifier.
of sunshine hours, and this makes it very advantageous to use solar power, so to further help compensate for increased electricity consumption, we are currently looking to install photovoltaic cells on a number of our south/south-west-facing properties. I am also looking at small wind turbines for some of the remote buildings, which are in exposed locations. Net Zero Carbon is a challenge, and we are being proactive in addressing the issues early on.”
Running ‘24/7’ The COVID pandemic has resulted in air-handling units being run 24/7. Units in healthcare premises that previously were switched off when the area was not in use are now being left to run continuously.
explains his experience of advising on increasing ventilation while keeping energy usage down. He says: “The basic principle is to provide the necessary ventilation utilising the minimum amount of energy. In the past the air-handling units in operating theatres were put in ‘set-back’, which meant they were running at half fan speed. In the past few years it has been recommended to turn operating theatre plant ‘off’ 15 minutes after finishing the last procedure – a step which can be automated via sensing of the last movement in the theatre or on a time schedule on the Building Management System (BMS), or via a connection to the theatre lights. The plant is then reactivated 30 minutes before starting an operation. Modern plant put on ‘Night Set Back’ sees the plant switched off. Of course some emergency operating theatres have to be left running ‘24/7’, but these are the exception. These standards are now in the new HTM 03-01, which has as one if its main drivers the Net Zero Carbon agenda. “Many ventilation systems,” David
Livingstone continues, “completely shut down when the facility is not in active use. If the system needs to be ‘on’ outside of normal occupancy hours to maintain minimum conditions – for example to run relative sensor or dew point sensors in the environment to prevent excessive humidity – the plant should run at a predetermined minimum speed, which in the past was half speed, during unoccupied periods.”
HTM guidance Areas that prior to COVID-19 were not deemed to require measured rates of ventilation have now come under the guidance of the HTM03-01. For example, suites used for the administration of Electro Convulsive Therapy (ECT) in
Image courtesy of Air Sentry Ltd
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