As part of the online event FIREX Connect 2021, an expert panel discussed the issue of fire safety in tall residential buildings, focussing on evacuation strategies and evacuation alert systems.
The session’s moderator, Gerry Dunphy, Event Director for IFSEC and FIREX International, opened the discussion by saying that, while the challenges of fire safety for tall buildings have been around for many decades, the 2017 Grenfell Tower fire revealed the complexities of maintaining a compliant building alongside a strategy to evacuate buildings of this type in an emergency. An event of this magnitude poses many questions around building control, public safety, construction methods and the emergency response, and the government has responded with far-reaching horizontal reviews, guidelines, and legislation.
Such a discussion, he said, encompasses the impact on building control, potential changes to legislation, new codes of practice and approaches to emergency evacuation from a technology and operational standpoint. It will examine current approaches to evacuating tall buildings, the challenges faced by fire safety professionals, the technological solutions helping to meet these challenges and the impacts of potential changes to legislation.
Andy Scott, Chair of BSI’s committee on alarm devices, voice alarm evacuation sub-systems and emergency voice communications and a Director at manufacturer C-Tec, discussed the implications of BS 8629: 2019, an important standard which introduces a new technological solution for evacuation alert systems to be used by fire and rescue services in apartment blocks.
He said the word ‘alert’ was used deliberately to differentiate from conventional fire alarms, as the main difference between the two is that evacuation alert systems do not have a detection element. They are legally required in new residential buildings over 18m in Scotland, but in the rest of the UK at present, installing evacuation alert systems is a risk assessed decision, though it has been suggested that they will be going into Building Regulations in due course.
The Grenfell Tower inquiry recommended that evacuation alert systems should be fitted in all new and existing high rise residential blocks, said Andy Scott. Controls are manually operated by the fire and rescue services if they think that a stay put policy is no longer viable. As the operation of evacuation alert systems is down to fire and rescue services, there’s been a huge input from them, the work on the standard having been steered by BSI’s FSH/17 committee, which oversees standards for firefighting and firefighters’ equipment.
Richard Clark, Senior Fire Engineer at the National Fire Chiefs’ Council, moved on to evacuation policies, and explained the theory behind the ‘stay put’ policy. ‘Stay put’ has been enshrined in building design codes since the 1960s. It means that if you have a fire in your flat you should evacuate, but compartmentation should allow others in that building to stay in their flats without being immediately negatively affected by the fire.
In the aftermath of the Grenfell Tower fire, waking watch schemes – which are like a human version of a fire alarm – have been introduced in some residential buildings. But these, he said, should only be used as a short-term measure, and only for buildings where cladding poses a risk of rapid-fire spread.
‘Stay put’ is by far the most common approach for people in high rise residential buildings, said Russ Timpson, Managing Director of the Tall Buildings Fire Safety Network. But there are differences around the world. In Germany, for example, the decision of whether to evacuate is left to the building occupants.
When designing a building, Russ Timpson said, the evacuation policy is taken into account for designing and specifying aspects such as staircases. So, if evacuation strategies end up being changed, there may be aspects of a building that may not be adequate for that change, and which were designed for small numbers leaving at any given time. If a lot of people need to leave suddenly, then there are question marks. In this country we build a lot of tall residential buildings with a single staircase, he said, but this would not be allowed in some other countries.
Russ Timpson went on to say that there’s a bit of a reality gap between the expectations of residents and the reality of actual fire safety in buildings. Other tall buildings operate phased evacuation where you only evacuate two or three floors when there’s a fire. Simultaneous evacuation can also affect the assumptions that have been made for stairs protected by pressurisation systems, as these are built on the premise that only a limited number of doors opening up to stairs are opened during evacuation.
Also, when stay put turns to simultaneous evacuation, there’s the risk of congestion on stairs and contraflow with firefighters trying to come up them. We know there’s going to be a need to change evacuation strategies, he said, so we need to implement this change process and BS 8629 is very much part of that process. But these evacuation systems must be implemented and installed as part of a change process involving all stakeholders.
Compared to other high-rise fires around the world, he said, we need to ask ourselves why the outcome at Grenfell Tower was so very different to those.
Consideration should be given to changing evacuation strategies when:
“There have been countless examples of fires not remaining in the compartment or the floor of origin,” added Russ. We also must take human behaviour into account, he said, especially together with social media. “As fire engineers, we have to sometimes put ourselves in the shoes of the residents and not necessarily look at this as a sterile engineering activity.”
Post-Grenfell, he said, it is foreseeable that you may need to change your evacuation strategy during a fire incident. This adaptability needs to be considered and facilities like BS 8629 have got to be provided to enable it. It’s a major change and it’s foreseeable, and we should be reflecting that in risk assessments.
On the question of how to ensure that systems installed are fit for purpose, Andy Scott said that BS 8629 is a code of practice which gives recommendations and nothing in it is mandatory. So, it is recommended that you use a competent installation and maintenance firm, and BAFE provides a method of measuring competence. “If you’re responsible for fire safety and you’ve used some chap from round the corner who could do it cheaper, then hopefully you’ll reap the consequences if something should go wrong,” he said.
“What I don’t understand is why we go from no form of evacuation to emptying the whole building all in one go. Evacuation alert systems don’t do that – they do it on a floor-by-floor basis. Automatic alarm systems don’t need to do that either. It’s called phased evacuation, but it doesn’t seem to be on the agenda. There may be cases where it’s not appropriate, but I don’t understand why it isn’t being discussed.”
Russ Timpson added: “We have to recognise the human behaviour in this. Despite phasing systems and phased evacuation signals – despite all the technology and all of the intent of the designers and fire engineers – you may well still end up with a simultaneous evacuation because of human behaviour.”
About people’s behaviour, part of the new requirements in the Building Safety Bill is to have a tenants’ engagement strategy. But if you are going to live in a high-rise residential building you are going to have to accept a degree of collective responsibility for your behaviour, such as not having a barbecue on a balcony or having a hoarding tendency.
Richard Clark concluded that the new building safety regime will impose additional requirements on these buildings, such as the safety case and having building safety managers in place who should have oversight of safety within those buildings. For example, if a contractor comes to install a satellite dish, there’ll be proper routes to oversee that kind of work, be aware of it, and make sure it happens properly, and residents will have a contact point to air their issues resulting in whole building responsibility.
To watch the full ‘Evacuation of Tall Buildings’ webinar, click here or simply watch below.
