Becky Blackmore: Welcome to the first in a series of podcasts which will address the pertinent issues around smoke control and fire safety. I’m Becky Blackmore, Marketing Communications Manager for SE Controls and I’m joined by Nelson Godinho Fire Engineer for SE Controls. Today’s topic is the eagerly anticipated CFD guide from the Smoke Control Association; Nelson is the chairperson for the working group who aim to release an updated version of the guide imminently:
For clarification purposes CFD stands for Computational Fluid Dynamics.
Good Afternoon Nelson, thanks for joining me.
Nelson Godinho: Hi Becky, pleasure to be here.
Becky Blackmore: I suppose the first question I would like to ask you is what is the CFD Guide and why is it being updated now?
Nelson Godinho: The first version of the guide back in 2007 was focused on providing guidance for using CFD to design smoke control systems in car parks, particularly when alternative systems such as impulse ventilation were proposed. Since then it’s [CFD] use has expanded to all types of buildings and we’re seeing more designers getting involved in it. So, as we had back in 2007, guidance on its use for designers or approving authorities is light across the broad, which is what the guidance is trying to address.
Becky Blackmore: Right ok, so would you say this lack of guidance is currently affecting the industry?
Nelson Godinho: Yes, I think it is to an extent, as we see more designers making use of it, we’re starting to see all manner of design ideas for modelling smoke control systems with people coming up with new ideas, some very clever and some not so clever. What we are starting to see in the most extreme cases is either very ambitious and impractical solutions, whilst on the other hand we also find grossly under engineered solutions where we can see they were in pursuit of convenient results.
Becky Blackmore: Right, I see your point so what you are saying is you would like to see more consistency in the designs?
Nelson Godinho: Yeah absolutely that’s what the industry is trying to grapple with at the moment.
Becky Blackmore: How important is CFD modelling for an effective smoke control strategy?
Nelson Godinho: CFD has become the primary computer aided design tool in the smoke control industry. This is because the main advantage for using it, is that the system can validate prior to construction which can give everyone confidence early in the project. The other advantage is that it can capture the effects of a complex building geometry that could not be accurately observed with empirical calculations. However, CFD does have its limitations, and none more important than the users. As with all things, the more people that are getting involved the more we start to see inexperienced users entering the field without clear understanding of the physics behind the colourful images and animations. It’s like the old saying, “if you put rubbish in, then you’ll get rubbish out”.
Becky Blackmore: Yes, indeed. What key elements in the guide have been updated and why are these being changed now?
Nelson Godinho: Just to put the foundation on it, the guide sets out the information and parameters that should be incorporate into CFD models with the intention helping the designer produce, run the CFD and then write the report.
The new guide will include the usual important sections about suitable qualifications, early qualitative design review, software limitations, reporting and so on. However, some of the new items include a section on the 3rd party review process, typical performance objectives for different applications and a new section on ‘best practice’ guidance for designing smoke control systems that you should also incorporate into your model.
Then there is also a lot of useful information on things like different options for modelling the fire and smoke source, mesh quality along with some of the original content that’s still relevant today.
Becky Blackmore: OK, that sounds really interesting. So what can we expect from this best practice guidance that you mention?
Nelson Godinho: The new section will set out key parameters that should be incorporated into the model for example, at which point or air velocity threshold should cars be included in a car park model, or where fire scenario locations should be selected for extended corridors in apartment buildings. This framework will hopefully help designers include these key parameters for a robust solution.
Becky Blackmore: You mention designers quite frequently, is that who this guide is aimed at or will anyone else benefit from the guide, such as Architects for example?
Nelson Godinho: Unless architects have their own inhouse fire engineer, then yes, otherwise its mainly for any designer whose involved in developing a smoke control solution, which ranges from your specialist contractor installing the system to fire engineering consultant providing the concept design. But more so, it also provides guidance to approving authorities who then evaluate those designs or third parties.
Becky Blackmore: OK but who would be the approving authorities?
Nelson Godinho: This would be your building control or fire brigade officer, any authority having jurisdiction on a building who will oversee the CFD model.
Becky Blackmore: Who was involved in re-writing the guide and how long has it taken to re-write?
Nelson Godinho: The document took around 2 years and we had a broad scope of expertise across the industry. These included specialist contractors, fire engineering consultants, professional CFD service providers, building control authorities as well as fire brigade authorities. So, we had a balanced representation of the industry, a good mix of ideas that came together to put the guide together.
Becky Blackmore: 2 years is a long time, when do you think the guide will be released and how can it be accessed?
Nelson Godinho: You say two years, you’re right. I think the problems in the current climate surrounding COVID delayed progress however, things are now finally moving forward. The draft in its final form is going through its final approval stages so I believe that we should have the guide for publication to download from the SCA website before the end of the year or as early as the beginning of next year.
Becky Blackmore: This all sounds positive and leads nicely to my final question… After this guide what’s next?
Nelson Godinho: Well I would like to go on holiday… but after that, I won’t be stopping any time soon I can tell you. Currently there are other guides being developed by the SCA that I’m working on but further afield, I’m also doing European committee work on smoke control related design guides, and I’m also a member of the committee currently reviewing the BS9991 standard, so there’s still lots to do on top of my usual every day work.
Becky Blackmore: You sound a very busy man but that’s brilliant thanks Nelson, thanks for your time today. We look forward to the release of the guide and finding out more about the key elements you’ve discussed with us today.
We’ll also send out a post upon the release of the guide and further information will be found at www.secontrols.com. Thanks Nelson.
Nelson Godinho: Thanks Becky it’s been a pleasure.