By Ron Burns
I have skirted around the topic of multi-level buildings for a year now, but as this is probably the largest fire risk in South Africa today, the time has come to tackle the issue.
Our cities are filled with multi-level buildings; each day the risk of a fire erupting and a building being gutted by fire becomes more of a reality. After the fire in London and this single headline on CBS News, ‘Thousands displaced from London homes as UK fire-safety crisis expands,’ I felt it was time to venture into multi-level buildings.
Further down the article the following headline question is raised, ‘Grenfell Tower fire: could it happen here?’
I would like to express my opinion on this current ‘hot topic’.
I thoroughly enjoy the opportunity to work through a series of smoke ventilation calculations, study the geometry of the building, and explore the opportunities of ensuring smoke is ventilated out of buildings. I see warehouse case studies flooding across my desk in rapid succession, but not too many office blocks or multi-level developments. In previous articles I have produced a series of guidelines in approaching these buildings. Warehouse smoke systems are simple ‘starter pack’ smoke ventilation designs providing few challenges; in fact, I have generated a series of tables for different altitudes — offering a solution is efficiently simple.
Having said ‘simple’, the number of projects I see with fundamental flaws is astounding. It would be fair to say South Africans are living in the ‘age of the alibi’. The opportunity to be accountable and provide solutions that are a little more expensive, yet work, fail us. A quick example to create some perspective: A series of smoke calculations are worked through and the designer places a lot of effort in evaluating the risk profile, the height of the warehouse, the levels in the internal mezzanine offices, and selecting the fire size. Care is taken to keep the smoke above the level of the internal office windows to protect the administration staff, and the crane level is carefully considered. The requirement to provide an aerodynamic free area is derived
The time has arrived to select the smoke ventilation equipment and position the ventilators in the roof. Eight ventilators are required, duly selected, and positioned. Inlet air louvres are scattered at low level around the building and a reliable smoke ventilation contractor is asked to do a budget check. The value comes back and a breakdown is offered, allowing the designer the opportunity to see how the money is distributed in the smoke ventilation system. The system is above budget. The following steps are what continues to surprise me: “It is time to rationalise the design.” In the air-conditioning market, the term ‘value engineering’ is thrown around faster than the All Blacks can distribute a rugby ball, and the wattage per square metre is adjusted, knowing that design days may happen over the weekend and seldom in consecutive days. In smoke ventilation, the system is ‘rationalised’. One day soon this concept will be explained to me; a fire is a fire, is a fire. I fail to see how the smoke generated can be rationalised. You can change the parameters, but then I need to pose the question so elegantly asked by Double You on their album We All Need Love, “Who’s Fooling Who.”
A smoke ventilation system that is rationalised by changing the behaviour of the smoke in a fire condition and selecting a product based on area rather than functionality and system requirements, is false economics.
Time to solve the smoke ventilation financially. Firstly, the make-up air is removed under the guise of make-up air being provided through the roller shutter doors. This means that in a 168-hour week, the make-up air is only available for 40 hours, provided the roller shutter doors are open for the duration of the business trading hours. This equates to a system that can only be effective for 23.9% of the building’s life (excluding annual leave periods). The budget is checked and again found higher than what the financial constraints provide for. The next step in rationalisation is to move away from the certified smoke ventilation equipment. Time to install some static ventilators. The one option is either a ‘ridge ventilator’, untested, with no high temperature performance testing or figures available. The other option is the use of a vertical louvre. An earlier article on vertical venting covered the risks of these products. The budget is checked and the design now meets the financial constraint. The financial team is satisfied and the system designer now carries the design risk, while the financial team enjoys a back-slapping moment of meeting their budget. Most fires are caused by electrical faults; the electrical feed to the building is there 100% of the time — not 23.9%. The fire risk never diminishes and will be remembered long after the euphoria of meeting budget is enjoyed.
I am always amazed at how the smoke ventilation system can be changed from a R10 system, which operates efficiently under all conditions keeping the desired clear layer in a building, to a smoke ventilation system that costs R8.
A smoke ventilation system that is rationalised by changing the behaviour of the smoke in a fire condition and selecting a product based on area rather than functionality and system requirements is false economics. The rationalised system will only maintain the clear layer in the building under very specific conditions, provided the fire breaks out during office hours, and depending on the ambient wind conditions. And, provided the roller shutter door is open and the staff can use the hose reel to fight the fire, thereby ensuring the perimeter does not grow beyond 6m.
If I were the client, if I were aware of the associated risk of saving money on a ‘rationalised system’, I would rather spend the additional amount and limit my risk. I think it is time to apply the principle, ‘keep important systems serviceable’.
In recapping how easy it is to get distracted on a budget constraint, let us explore the Grenfell Tower fire. I need to make a few factual statements:
- The loss of life is tragic and as a community of individuals involved in any form of fire engineering, it is regrettable and deeply saddening that at present 79 people have lost their lives. I extend heartfelt sympathies to their families and loved ones.
- The investigation is ongoing and I am not drawing conclusions regarding the fire.
- A perfectly designed smoke control system would not have saved all 79 lives lost in the fire.
Let us look at what went wrong:
- The building had only one fire escape in the central core. Once access to the single escape route is unavailable, it becomes unlikely that the occupants can escape safely. (Source: www.bbc.com.)
- The building was cladded with an external skin, providing a cavity for the transport of smoke and heat.
- Politicians are blaming the opposition to score political points instead of looking at the reasons for the deaths (sound familiar).
- There is no mention of a sprinkler system being installed.
- There is no mention of a smoke ventilation system.
A comparison to the multi-level buildings in South Africa:
- The building had only one fire escape in the central core. Once access to the single escape route is unavailable, it becomes unlikely that the occupants can escape safely. In my dealings with fire engineers in South Africa, this is definitely the default ‘go-to setting’. A respect for escape provision is the uncompromised position. I have not seen a building where any escape is compromised. One of the problems in the Grenfell Tower fire is the start of the fire. The first photo I saw of the fire is timed as being 1:30 in the morning. Most of the occupants are sleeping. Smoke is the largest killer in a fire. Smoke is silent. Smoke moves without creating awareness. You can smell smoke, which may wake you up. Once awake and orientated, you would have lost precious time in escaping. If this fire had erupted on a working morning, I am sure the loss of life would have been substantially less.
- The building was cladded with an external skin, providing a cavity for the transport of smoke and heat. There is a lot of debate relating to the cladding of the building, perhaps too much. I am always amazed at the accuracy of hindsight, definitely 20/20 vision. There is debate around the combustibility of the cladding and I want to scratch here a little. If the cladding was replaced by an additional brick skin and the same air gap was created between such brick skin and the existing skin of the building, the same chimney scenario would have been created. An external brick skin would have been far worse. If the cladding had been paper, the smoke and the fire would have broken through the cladding and ventilated to the external facade and not ‘preheated’ the entire external facade of the building. Ensuring the fire integrity between the individual levels of the building is critical, irrespective of the material used to provide the external facade.
As South Africans, we should carefully look at the atria being designed into our multi-level buildings. Are we creating a chimney in a building? Are we interconnecting multiple levels? Are we creating the ‘perfect storm’ environment? How many levels are too many to connect? If the footprint is less than 500m2 in a multi-level building, should we ventilate it? Are these crazy questions or can we rationalise them out of the design? Why are we fixated on the 500m2 rule? If the room shares a common void, the smoke will travel as it did in the Grenfell Tower fire. Are we at risk? Are others at risk?
- Politicians are blaming the opposition to score political points instead of looking at the reasons for the deaths. There is nothing I can add to this. Blame is shifted like a hot potato. Too much time bragging and blaming, insufficient time spent discussing prevention. I wonder if they ever asked themselves, “What action could we have taken to prevent the loss of lives in any building?”
- There is no mention of a sprinkler system being installed. In South Africa, there is much debate on the interaction between the sprinklers and the smoke ventilation system. A really tedious debate involving personal opinions and limited scientific research. I do not want to open this debate at this point. I do want to list these facts. In my opinion:
- A building designed without sprinklers is designed to burn to the ground in the event of a fire.
- A building without sprinklers makes it impossible to design a smoke ventilation system with a ‘guaranteed’ smoke clear layer.
- Smoke is the biggest killer in the event of a fire.
- If the building is worth constructing and investing in, it is worth protecting.
- A smoke ventilation system without a sprinkler system is worthless.
- There is no mention of a smoke ventilation system. From the information I have, it is difficult to determine the building footprint. In South Africa, if the Grenfell Tower building had been constructed and divided into rooms less than 500m2, no smoke ventilation system would have been installed.
Are we able to answer the question asked earlier, “Grenfell Tower fire: could it happen here?”
I would suggest that the possibility is not only real, but largely overdue. A drive through Hillbrow adds a spark of reality to that question. I am seeing more multi-level buildings with smoke ventilation system provision than I did 10 years ago. Enough? No, not nearly. Is the market ready to embrace the installation of smoke ventilation systems into all the multi-level buildings? I personally hope so. It is going to have financial implications as South Africa grows as a nation. We need to embrace the concept of the principle ‘keep important systems serviceable’ as we develop, hopefully without any severe consequences.
The challenge to all fire engineers is to affect these principles in the minds of developers and building owners. Mr Fire Engineer, your science is important to the lives of South Africans, whether they appreciate it or not. When fire grips their buildings and their survival depends on your provisions, your decisions, your knowledge, then you save lives! Your thought process makes the difference. Keep fighting the good fight. Your impact on South Africa is invaluable.
My final thoughts are reflected in this quotation by the great parliamentarian Edmund Burke, “The only thing necessary for the triumph of evil is for good men to do nothing.”