FIRE SAFETY
Figure 2: Mass timber and glulam beams will feature in the atrium of the new Velindre Cancer Centre in Cardiff.
Such construction and timber
components posed some fire safety issues. Anthony Pitcher elaborated: “With a relatively flat ceiling, it’s easy to work out the detector spacing and the sprinkler protection, but a large space – broken up with extremely deep down- stand beams – has implications in terms of elements such as a need for more automatic fire detectors (AFDs), and the sprinkler protection will be steered by that too.” Anthony Pitcher said another consideration was that deep beams can restrict ceiling voids. He explained: “We all know how congested hospital ceiling voids are – for elements such as services and maintenance etc.”
Impact of future modifications The fire safety specialist said one element that the sector perhaps paid insufficient attention to was potential future building modifications. He said: “The NHS is continuously evolving, and if we are using CLT mass timber, we need to determine whether this imposes restrictions on future flexibility.” On what he dubbed a ‘positive note’, he added: “If you’re using materials of limited combustibility for your structural elements, then the building will be sprinkler protected – from a fire safety perspective this is a huge step in the right direction. I am very ‘pro sprinklers’, and we have achieved extensive progress in Welsh healthcare facilities with sprinkler protection, which will hopefully continue.” The NHS Wales speaker’s next focus was guidance. He explained that bodies such as the Structural Timber Association, and RISE (The Research Institute of Sweden), had produced ‘masses of guidance’ on this topic (Figure 3). “However,” he added, “they recognise that it is an extremely specialist field. As several previous speakers said earlier today, there is also a massive skills shortage in this particular area.” There was, however, ‘a lot of ongoing research, with a continuously evolving database and evidence base’.
38 Health Estate Journal September 2023
The speaker’s view was that the NHS isn’t yet ready for mass timber construction. He added: “Perhaps I should qualify that. The images we saw of Velindre show an atrium – so there is no direct patient care there, while, importantly, the building has full sprinkler protection against fire. Also, on the scheme there are other parts of the building – on the upper levels – which are purely administrative, with no patient access. Again, mass timber has its place, but I don’t think the NHS is ready for mass timber in inpatient facilities. That’s my view, but – as I said – there’s a lot of research ongoing, so maybe things will change in the future.” Here, Anthony Pitcher said he wanted
to discuss ‘electrification’. He said: “Why is this such a concern to us in the NHS? Well – statistically, and consistently, over the past 10 years, the biggest cause of NHS fires has been some form of electrical failure (Figure 4). We are putting ever- increasing demand on the electrical infrastructure, and as several speakers this morning recognised, the estate is tired – and so is the electrical infrastructure. We must therefore be very careful about what additional load we add.”
Operational carbon Turning to the operational carbon associated with various forms of electrification, and Anthony Pitcher said one of the most significant changes is the adoption of photovoltaic plant. He said: “Some 99% of all the business cases that come across our desk for scrutiny today include PV installations. There’s a massive growth in PV, and rightly so, given the decarbonisation agenda.” Looking at some of the key PV system components, the speaker explained: “The DC cabling is extremely dangerous, and thus the Fire Service needs to isolate it; any delay in doing so could hold up firefighting activities, which could have significant consequences for the outcome of the fire.” Showing a slide of the key components of a PV system, he highlighted the PV
panels on the roof, a DC cable shown in red, and its feed into an inverter. The inverter then fed out AC cable connected to the electrical infrastructure. It was vital, he stressed, for the DC cabling to be isolated. “So,” he asked, where do we isolate? Well, ideally,” he responded, “you should be isolating at source. However,” he explained, “this is one of the problems we have.” Now,” he added, “the image on the right (Figure 5) on a slide titled ‘PV fire-fighting risk’ is an isolator.” On it – in small text – is the message: ‘Solar PV Firefighter Switch, Please note: DC voltage will be reduced to a safe level’. The speaker said: “I’d question that. Without sufficient information, is that just to isolate the AC supply to the inverter to turn the inverter off? If so, the red cabling coming down from the PV panel to the inverter has potentially still got significantly high voltages running through it. We need clearer information on that.” Showing another slide (Figure 6), he
said: “This is a pair of inverters, with the red isolators being the AC ones, and the grey ones the DC string isolators.” This equipment was located in a hospital ward pantry, ‘not the safest place to install such kit’. He said: “These are some of the challenges we are facing.” As to the fire safety risks from PV arrays
and associated equipment, Anthony Pitcher said that ‘when one thinks of the millions of panels and systems installed across both the NHS estate and many installations in other sectors, they don’t catch fire every day’. The BRE and the IEC had ‘conducted a fair bit of research’ on this, which was now ‘slightly dated’. He said: “They identified that the most probable or common causes with PV- related fires were poor installation and component failure, and instances where there was water ingress, or inappropriate AC / DC isolators etc.”
A continuous arc He went on to explain that DC current gives a continuous arc, with a higher
Images used courtesy of White Arkitekter.
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